an apparition, something made supernaturally visible to human sight, whether the ghosts of dead men or beings superior to man.

A belief that supernatural beings sometimes make themselves visible, and that the dead sometimes revisit the living, has prevailed among most nations, especially in the rudest stages of society. It was common among the Jews, among the Greeks, and among the Romans, as we find from the Scriptures, and from the poems of Homer and Virgil. Celestial appearances were indeed so often exhibited to the Jews, that the origin of their belief is not difficult to be explained.—The Divine Being manifested himself to each of the Patriarchs by some sensible sign, generally by a flame of fire, as he did to Moses. Under this semblance also did he appear to the Israelites during their abode in the desert, and after they obtained a settlement in the land of Canaan. Nor did they believe that heavenly beings alone assumed a sensible appearance: They believed that deceased men also sometimes revisited this world. When Saul went to consult the witch at Endor, he asked her to bring up the person whom he should name unto her; a proof that he considered his demand as easy to be performed, and therefore that he probably acted under the influence of popular opinion. The same opinions had been generally entertained at a much earlier period; for necromancy and witchcraft, the arts by which the dead were supposed to be raised, had been prohibited while the Israelites were in the wilderness, and yet untainted with the vices of the Canaanites. They must therefore have derived them from Egypt, the cradle of superstition, as well as of the arts and sciences.

Among the Greeks and Romans the apparition of spectres was generally believed. On innumerable occasions the gods are said to have discovered themselves to the eyes of mortals, to have held conferences, and to have interposed their aid. The ghosts of the dead, too, are said to have appeared. When Æneas, amidst the distraction and confusion of his mind in flying from the destruction of Troy, had lost his wife by the way, he returned in search of her. Her shade appeared to him (for she herself had been slain) with the same aspect as before, but her figure was larger. She endeavoured to assuage the grief of her unhappy husband, by ascribing her death to the appointment of the gods, and by foretelling the illustrious honours which yet awaited him. But when Æneas attempted to clasp her in his arms, the phantom immediately vanished into air. From this story we may observe, that the ancients believed that the umbrae or shades, retained nearly the same appearance after death as before; that they had so far the resemblance of a body as to be visible; that they could think and speak as formerly, but could not be touched. This description applies equally well to those shades which had passed the river Styx, and taken up their residence in the infernal regions. Such were the shades of Dido, of Deiphobus, and all those which Æneas met with in his journey through the subterraneous world.

It appears from the writings of modern travellers who have visited rude and savage nations, that the belief of spectres is no less common among them. Mr Bruce tells us, that the priest of the Nile affirmed, that he had more than once seen the spirit of the river in the form of an old man with a white beard. Among the Mahometans the doctrine of spectres seems to be reduced to a regular system, by the accounts which they give of genii. Whoever has read the Arabian Nights Entertainments must have furnished his memory with a thousand instances of this kind. Their opinions concerning genii seem to be a corrupted mixture of the doctrines of the Jews and ancient Persians. In Christian countries, too, notwithstanding the additional light which their religion has spread, and the great improvement in the sciences to which it has been subservient, the belief of ghosts and apparitions is very general, especially among the lower ranks. They believe that evil spirits sometimes make their appearance in order to terrify wicked men, especially those who have committed murder.—They suppose that the spirits of dead men assume a corporeal appearance, hover about church yards and the houses of the deceased, or haunt the places where murders have been committed. (See Ghost.) In some places it is believed that beings have been seen bearing a perfect resemblance to men alive. In the Highlands of Scotland, what is called the second sight is still believed by many (see Second Sight); viz. that future events are foretold by certain individuals by means of spectral representation.

So general has the belief of spectres been, that this circumstance alone may be thought by some sufficient to prove that it must have its foundation in human nature, or must rest upon rational evidence. When any doctrine has been universally received by all nations, by generations living several thousand years from one another, and by people in all the different stages of society, there is certainly the strongest presumption to conclude that such a doctrine has its foundation in reason and in truth. In this way we argue in favour of the existence of a God, concerning moral distinction, and the doctrine of a future state; and certainly so far we argue well. But if the same argument be applied to idolatry, to sacrifices, or to apparitions, we shall find that it is applied improperly. Idolatry was very general among ancient nations; so was the offering of sacrifices. so was polytheism: but they were by no means universal. Should we allow, for the sake of shortening the argument, that all ancient nations were polytheists and idolaters, and presented oblations to their imaginary deities, all that could be concluded from this conception is, that they fell into these mistakes from their ignorance and from the rude state of society, from which their imperfect knowledge of theology and moral philosophy was never able to rescue them. These erroneous notions fled before the brightness of the Christian system; while the doctrines of the existence of God, of moral distinction, and of a future state, have been more thoroughly confirmed and ascertained. The same thing may be said of the belief of spectres. However generally it has been adopted in the first stages of society, or by civilized nations who had made but little progress in the study of divine things, it has been rejected, we may say invariably, wherever theology and philosophy have gone hand in hand.

As all popular and long established opinions are objects of curiosity and research for the philosopher, we think the belief of spectres worthy of some attention even in this light. It will therefore, we hope, give some satisfaction to the philosophical reader to see a short account of the sources or principles from which this belief is derived. But as the belief of spectres is connected with other opinions which appear to us highly injurious to religion; opinions which have been supported by many learned men, and which are still believed by some men of literary education—it will also be proper, in the first place, to consider the evidence on which this belief rests, in which we must consider both their probability and credibility.

In the present investigation we mean to set aside altogether the celestial appearances recorded in Scripture, as being founded on unquestionable evidence, and perfectly agreeable to those rules by which the Deity acts in the usual course of his Providence. The Israelites, during the existence of their state, were immediately under the authority of God, not only as the moral governor of the world, but as the king of Israel. In the infancy of the world, while men were rude and unenlightened, and entirely under the influence of idolatry, many revelations were necessary to preserve in their minds pure ideas of the nature of God, and of the worship due to Him. They were necessary also to pave the way for that illustrious dispensation which the Lord Jesus came from Heaven to diffuse over the world. Every celestial appearance recorded in Scripture was exhibited for some wise and important purpose, which must be apparent to every person who considers these appearances with attention. But when the Scriptures were written and published, and the Christian religion fully established, revelation ceased, and miracles and heavenly messengers were no longer requisite. What credit then ought we to give to those marvellous stories related in ancient authors concerning prodigies in the heavens, and the apparition of angels both good and bad?

It is not pretended that any of those prodigies and appearances were exhibited for purposes equally great and important with those which are described in Scripture: And can we suppose that the all-wise Governor of the World would permit his angels to render themselves visible to the eye of man for no purpose at all, or for a purpose which might have been equally well accomplished without their interposition? Would this be consistent with perfect wisdom, or would it be consistent even with the excellence and superiority of understanding which we are taught to ascribe to these elevated beings? The whole will of God is revealed to us in the Scriptures; what further use for the visible interposition of angels? It may be objected, Are they not all ministering spirits sent forth to minister for them who shall be heirs of salvation? We answer, That angels may animate and support good men by an invisible interposition. But the Apostle is not speaking of celestial spirits. The word "angelos" signifies "a messenger;" and in Scripture often refers to men. In the passage which we are now reviewing it certainly is applied with much more propriety to men than to angels: for the Apostle is stating a comparison between the Prophets, by whom God, at sundry times and in divers manners, spake in time past to the fathers, and the Son, by whom he hath spoken in these last days.

And if God has given no commission to his angels to deliver to men since the publication of the Christian religion, is there any probability that he would give any commission or any licence to evil spirits? It will be said, that this doctrine is clearly taught in the New Testament, in these words, "The devil goeth about as a roaring lion seeking whom he may devour." We will not avail ourselves of the interpretation of some, who say that the word devil, which in the Greek language signifies an adversary, or slanderer, refers here to some human being, who was a violent enemy of the Christians. All that can be deduced from these words, upon the supposition that they refer to a malignant spirit, is merely that he goeth about seducing men to vice. But it is not by assuming a hideous form, and presenting himself to the midnight traveller, that such a purpose is to be accomplished. A spirit may probably have direct access to our minds without the intervention of anything corporeal; and by exciting our passions may plunge us into vice, which is the only object such a being is supposed to have in view. None of the marvellous stories which we have heard concerning the apparition of evil spirits lead us to conclude that they appear to entice men to commit crimes. We never heard of any evil spirits that required men to steal, to perpetrate robbery or murder. They only appeared to terrify some crazy timorous individuals, who have whims and fancies of their own to agitate their minds, though no supernatural vision should ever appear to them. It is not consistent, therefore, with the character of God, and what he has revealed to us of his will, to believe that he would commission good angels, or permit evil angels, to appear to men since the propagation of the gospel, or indeed at any former period of the world, unless some great and mighty purpose was to be fulfilled. It is not consistent with what we know of the nature of good or bad angels to suppose, that though permission were granted them occasionally to show themselves to men, that they would appear in that way which storytellers describe.

It is equally improbable that the spirits of the dead who have removed from this world should again be permitted to visit it. At death men undergo as great, perhaps a greater change, than when they came first into the light of the sun. Is it not therefore as improbable that a man should return in a visible corporeal form form after death, as that, after having arrived at manhood, he should return to the state in which he was before his birth? Such changes as these are evidently made permanent by the invariable laws of nature. But suppose it were possible, for what purpose should they return? To describe to us what is passing in the other world, to animate us to virtue, by informing us of the rewards which there await the good; or to alarm us, by describing the punishment of the wicked. These seem important reasons. But Divine Providence has wisely thrown a veil over futurity. We know everything of the other world from the scripture which it is proper for us at present to know. And as to incentives to virtue, we are already blessed with a number sufficiently great and powerful for moral beings, who are to act from rational motives, and not from compulsion. "He that will not hear Moses and the prophets, will not be persuaded though one rose from the dead."

There is one strong objection against the probability of spectres, which is sufficient to prove that they are not intelligent creatures; or at least that they possess so small a degree of intelligence, that they are unqualified to act with prudence, to propose any end to themselves, or use the proper means to accomplish that end. Ghosts often appear in order to discover some crime that has been committed; but they never appear to a magistrate, or person in authority, but to some illiterate clown, who happens to live near the place where the crime was perpetrated; to some person who has no connection with the affair at all, and who in general is the most improper in the world for making the discovery. For instance, in Glanville's *Sudelus* (a book written in the last century by a chaplain of Charles II. in support of the common opinions respecting witchcraft and apparitions), we have the following story: James Haddock, a farmer, was married to Eleanor Welsh, by whom he had a son. After the death of Haddock, his wife married one Davis; and both agreed to defraud the son by the former marriage of a leafe bequeathed to him by his father. Upon this the ghost of Haddock appeared to one Francis Taverner the servant of lord Chichester, and desired him to go to Eleanor Welsh, and to inform her that it was the will of her former husband that their son should enjoy the leafe. Taverner did not at first execute this commission; but he was continually haunted by the apparition in the most hideous shapes, which even threatened to tear him in pieces, till at last he delivered the message. Now, had this spectre had the least common sense, it would have appeared first to Eleanor Welsh and her husband Davis, and frightened them into compliance at once, and not have kept poor Taverner in such constant diliquitude, who had no concern in the matter.

Another very odd circumstance respecting apparitions in general must not be omitted, which is, that they have no power to speak till they are addressed. In the 27th of Glanville's Relations we read of an old woman that appeared often to David Hunter, a neat-herd, at the house of the Bishop of Down and Conners. Whenever she appeared, he found himself obliged to follow her; and for three quarters of a year poor David spent the whole of almost every night in scampering up and down through the woods after this old woman. How long this extraordinary employment might have continued, it is impossible to guess, had not David's violent nature made him one night exclaim, "Lord bless me! would I were dead!"—shall I never be delivered from this misery?" On which the phantom replied, "Lord bless me too! It was happy you spoke first, for till then I had no power to speak, though I have followed you so long." Then she gave him a message to her two sons, though David told her he remembered nothing about her. David, it seems, neglected to deliver the message; at which the old beldam was so much provoked, that she returned and hit him a hearty blow on the shoulder, which made him cry out, and then speak to her. Now if she could not speak till David addressed her, why might she not have applied this oratorical medicine the first time she appeared to him? It would have saved both herself and him many a weary journey; and certainly David would much rather have had even half a dozen of blows from her choppy than have wanted so many nights sleep. To complete the story, we must add, that when David's wife found it impossible to keep him from following the troublesome visitor, she struggled after him, but never was gratified with a sight of the enchantress. David's little dog too was a dutiful attendant on his master during his pilgrimage.

It is remarked by Glanville, that ghosts are generally very eager to be gone. Indeed they are often in such fear, that they do not stay to tell their errand. One would be induced from this, as well as the circumstances already mentioned, to think that they are the stupidest and dullest of the dead that assume the appearance of ghosts; unless we adopt the ingenious solution of Glanville, "that it is a very hard and painful thing for them to force their thin and tenuous bodies into a visible consistence; that their bodies must needs be exceedingly comprimised; and that therefore they must be in haste to be delivered from the unnatural pressure."

With respect to the evidence in favour of spectres, if examined ever so slightly, it will be found very defective. They only appear to one person at a time; they are seen only in the night; they are visible only to ignorant, illiterate, and credulous persons, and never present themselves before men of education and learning.

That spectres only appear to one person at a time, even though there are more in company, is an objection against the credibility of their appearance quite insurmountable. How is it possible that two men of eyesight equally good, directing their eyes to the same spot, should not see so large an object as that of a man or woman at a small distance equally well? Some will tell us that a mist is cast over the eyes of the one, while the view of the other is free from obstruction. But how is this to be proved? and besides what purpose would it serve? Ghosts have seldom any secrets to disclose; they might be proclaimed to a multitude with as much propriety as confined to one person. Shall we be told, that the spectre has the power of becoming visible to some, and of remaining invisible to others? This cannot be allowed without adopting opinions destructive to revealed religion; for it would be a miracle; and we cannot be persuaded, without evidence, that God would empower any inferior being to controul at pleasure the wise laws which he has ordained for governing the world. To him who is of a different opinion, we would recommend Farmer on Miracles; a book in which this question is fully examined.

Spectres appear only in the night. But why should they shun the light of the sun? Those, mischievous ghosts that Glanville mentions might indeed have some reason to choose midnight for the execution of their pranks, as they would be more easily detected in open day. Such was the roguish drummer that haunted Mr Mompesson's house, who beat his drum all night, threw the old gentleman's clothes about the room, hid her Bible in the ashes, plucked the clothes off the bed, and amused himself with tossing about Mr Mompesson's shoes. But why should a grave serious ghost appear at midnight? Might it not deliver its message with as much ease and more success in the daytime? In the daytime it would not excite much fear; it would be listened to therefore with more attention; and did it choose to exhibit itself before a number of witnesses, its grievances would be more speedily redressed, because more persons would interest themselves in seeing justice done to the injured ghost.

Spectres not only choose the most improper time, but the most improper persons. To render the testimony of any person credible, he must not only be a man of veracity, but he must have sufficient ability to judge of the subject to which he is to bear witness. It is not on the evidence of an ignorant illiterate person, who has more fancy and fear than judgment, that we are to rest our belief of what is supernatural. It is also worthy of remark, that we have never heard of a ghost appearing to any person who did not previously believe their existence. A man must be prejudiced in favour of this opinion, or he will never see a ghost. But sensible men know, that he who has been accustomed to hear frightful stories of ghosts and apparitions gliding through a church-yard, or haunting some particular place, can scarcely pass through a church-yard or haunted spot without conjuring up in his imagination the hideous phantoms which he has been accustomed to associate with such places. Is it strange, then, that an ignorant man, with a mind uncultivated and uninformed, with all the prejudices of the nursery about him, should imagine he sees ghosts in those places where he believes they hover, especially in the dead hour of midnight, when, with the slightest aid of the imagination, a cow may be turned into a monstrous phantom, and the reflection of the beams of the moon from a little water be converted into a ghost with a winding-sheet? But why should apparitions shun men of understanding and learning? Why should learning be formidable to them (A)? It was not so with the celestial messengers mentioned in the Scriptures: they appeared to the patriarchs and prophets; and the miracles there recorded were performed in the most public places, before the eyes of Rabbies, of Scribes, and Pharisees. Indeed this circumstance is sufficient to destroy the evidence of spectres. They have never been seen by any but men of weak or disordered minds, or by men who have previously believed in them.

Having now considered the evidence on which the belief of spectres rests, we will endeavour to give some account of the foundation of it. To trace an opinion that has prevailed so generally in the world to its source, is a labour not unworthy of the philosopher, even tho' the opinion be false. It is always gratifying to detect the causes of error: it is no less useful; for in order to refute error, it is often sufficient to point out the sources from which it has sprung. To reach the origin of the belief of spectres is not more difficult than to account for idolatry or polytheism. In the infant state of the intellectual powers every thing is considered as possessing life and intelligence. The child beats the stool over which he has fallen with the same passion that he would treat his companion: The young girl talks to her doll as if it understood her: The savages ascribe every change which they observe on the face of nature to the action of some animated being. As knowledge advances, they single out those beings which seem to produce the most striking effects, arrange them into some kind of order, and divide the government of the world among them. Unable, at the same time, to conceive any notion of a pure spirit, they imagine those divinities are corporeal beings. This is the foundation of idolatry. The belief of spectres is but another step, that these animated corporeal beings, to whom they address their prayers, and who pretend over the world, should on particular occasions display themselves to the human eye, is what they must be previously disposed to expect. Hence the numberless appearances of the heathen gods, of the Persian and Mahometan genii. The belief

(A) The celebrated historian De Thou had a very singular adventure at Saumur, in the year 1598. One night, having retired to rest very much fatigued, while he was enjoying a sound sleep, he felt a very extraordinary weight upon his feet, which, having made him turn suddenly, fell down and awakened him. At first he imagined that it had been only a dream, but hearing soon after some noise in his chamber, he drew aside the curtains, and saw, by help of the moon, which at that time shone very bright, a large white figure walking up and down, and at the same time observed upon a chair some rags, which he thought belonged to thieves who had come to rob him. The figure then approaching his bed, he had the courage to ask it what it was. "I am (said it) the Queen of Heaven." Had such a figure appeared to any credulous ignorant man in the dead of night, and made such a speech, would he not have trembled with fear, and have frightened the whole neighbourhood with a marvellous description of it? But De Thou had too much understanding to be so imposed upon. Upon hearing the words which dropped from the figure, he immediately concluded that it was some mad woman, got up, called his servants, and ordered them to turn her out of doors; after which he returned to bed and fell asleep. Next morning he found that he had not been deceived in his conjecture, and that having forgot to shut his door, this female figure had escaped from her keepers, and entered his apartment. The brave Schomberg, to whom De Thou related his adventure some days after, confessed that in such a case he would not have shown so much courage. The king also, who was informed of it by Schomberg, made the same acknowledgment. specific gravity of \(0.73\), from that of \(1.068793\), viz. \(0.028893\%\), and take \(0.041393\), the 40th part of the difference. Multiply this by \(1, 2, 3, \ldots\) and add the logarithm of \(0.73\) to each of the products. The sums are the logarithms of the specific gravities required. These will be found to proceed so equably, that they may be interpolated ten times by a simple table of proportional parts without the smallest sensible error. Therefore the stem may be divided into a hundred parts very sensible to the eye (each being nearly the 20th of an inch), and 400 degrees of specific gravity obtained within the range, which is as near as we can examine this matter by any hydrometer. Thus the specific gravities corresponding to no. 26, 27, 28, 29, are as follow:

| No. | Specific Gravity | |-----|------------------| | 26 | 0.93529 | | 27 | 0.94424 | | 28 | 0.95328 | | 29 | 0.96241 |

Nay, the trouble of inspecting a table may be avoided, by forming on a scale the logarithms of the numbers between 7300 and 1068793, and placing alongside of it a scale of the same length divided into 400 equal parts, numbered from 0 to 400. Then, looking for the mark shown by the hydrometer on this scale of equal parts, we see opposite to it the specific gravity.

We have been thus particular in the illustration of this mode of construction, because it is really a beautiful and commodious instrument, which may be of great use both to the naturalist and to the man of business. A table may be comprised in 20 octavo pages, which will contain the specific gravities of every fluid which can interest either, and answer every question relative to their admixture with as much precision as the observations can be made. We therefore recommend it to our readers, and we recommend the very example which we have given as one of the most convenient.

The instrument need not exceed eight inches in length, and may be contained in a pocket case of 2 inches broad and as many deep, which will also contain the scale, a thermometer, and even the table for applying it to all fluids which have been examined.

It is unfortunate that no graduated hydrometer can be made so easily for the examination of the corrosive mineral acids (a). These must be made of glass, and we cannot depend on the accurate cylindrical form of any glass stem. But if any such can be procured, the construction is the same. The divided scale may either be on thin paper pasted on the inside of the stem, or it may be printed on the stem itself from a plate, with ink made of a metallic calx, which will attach itself to the glass with a very moderate heat. We would recommend common white enamel, or arsenical glass, as the fittest material for the whole instrument; and the ink used, in taking the impression of the scale, may be the same that is used for the low-priced printing on Delft ware pottery.

First form the scale on the stem. Then, having measured the solid contents of the graduated part as exactly as possible, and determined on the general shape of the ball and counterpoise below, calculate its size, so that it may be a little less than ten times that of the stem. The glass blower can copy this very nearly, and join it to the stem. Then make two brines or other liquors, which shall have specific gravities in the ratio of 10 to 11. Load the instrument so that it may sink to 0 in the lightest. When put into the heaviest, it should rise to 10. If it does not rise so high, the immersed part is too small. Let the glass blower enlarge the ball of the counterpoise a little. Repeat this trial till it be exact. Nothing now remains but to form the weights: And here we observe, that when the instrument is to have a very great range, as for examining all states of the vitriolic acid, it has a chance of being very tottering when loaded with the greatest weight on the top of so long a scale. To avoid this, Mr Quin and others have added some of their weights below. But this will not suit the present construction, because it will alter the proportion between the bulks of the stem and immersed part. Therefore let these weights consist of cylinders of metal small enough to go into the stem, and let them be soldered to the end of long wires, which will let them go to the bottom, and leave a small hook or ring at top. These can lie alongside of the instrument in its case. This is indeed the best construction for every hydrometer, because it makes it incomparably more steady. The instrument is poised by small shot or mercury. But it will be much better to do it with Newton's fusible metal (three parts of tin, five parts of lead, and eight parts of bismuth) in coarse filings. When the exact quantity has been put in, the instrument may be let in a vessel of oil, and this kept on the fire till all is completely melted. It soon freezes again, and remains fast. If this metal is not to be had, let a few bits of sealing wax be added to the mercury or shot, to make up the counterpoise. When heated, it will float atop, and when it freezes again it will keep all fast. Thus we shall make a very complete and cheap instrument.

There is yet another method of examining the specific gravities of fluids, first proposed by Dr Willson, late professor of astronomy in the university of Glasgow. This is by a series of small glass bubbles, differing equally, or according to some rule, from each other in specific gravity, and each marked with its proper number. When these are thrown into a fluid which is to be examined, all those which are heavier than the fluid will fall to the bottom. Then holding the vessel in the hand, or near a fire or candle, the fluid expands, and one of the floating bubbles begins to sink. Its specific gravity, therefore, was either equal to, or a little less than, that of the fluid; and the degree of the thermometer, when it began to sink, will inform us how much it was deficient, if we know the law of expansion of the liquor. Sets of these bubbles fitted for the examination of spirituous liquors, with a little treatise showing the manner of using them, and calculating by the thermometer, are made by Mr Brown, an ingenious artist of Glasgow, and are often used by the dealers in spirits, being found both accurate and expeditious.

Alto, though a bubble or two should be broken, the strength of the spirits may easily be had by means of the remainder, unless two or three in immediate succession

(a) It would be worth while to try copper enamelled. be wanting; for a liquor which answers to No. 4 will fisk No. 2 by heating it a few degrees, and therefore No. 3 may be spared. This is a great advantage in ordinary business. A nice hydrometer is not only an expensive instrument, but exceedingly delicate, being so very thin. If broken or even bruised, it is useless, and can hardly be repaired except by the very maker.

As the only question here is, to determine how many gallons of excise proof spirits is contained in a quantity of liquor, the artist has constructed this series of bubbles in the simplest manner possible, by previously making 40 or 50 mixtures of spirits and water, and then adjusting the bubbles to these mixtures. In some sets the number on each bubble is the number of gallons of proof spirits contained in 100 gallons of the liquor. In other sets the number on each bubble expresses the gallons of water which will make a liquor of this strength, if added to 14 gallons of alcohol. Thus, if a liquor answers to No. 4, then 4 gallons of water added to 14 gallons of alcohol will make a liquor of this strength. The first is the best method; for we should be mistaken in supposing that 18 gallons, which answer to No. 4, contains exactly 14 gallons of alcohol: it contains more than 14, for a reason to be given by and by.

By examining the specific gravity of bodies, the philosopher has made some very curious discoveries. The most remarkable of these is the change which the density of bodies suffers by mixture. It is a most reasonable expectation, that when a cubic foot of one substance is mixed any how with a cubic foot of another, the bulk of the mixture will be two cubic feet; and that 18 gallons of water joined to 18 gallons of oil will fill a vessel of 36 gallons. Accordingly this was never doubted; and even Archimedes, the most scrupulous of mathematicians, proceeded on this supposition in the solution of his famous problem, the discovery of the proportion of silver and gold in a mixture of both. He does not even mention it as a postulate that may be granted him, so much did he conceive it to be an axiom. Yet a little reflection seems sufficient to make it doubtful, and to require examination. A box filled with musket-balls will receive a considerable quantity of small shot, and after this a considerable quantity of fine sand, and after this a considerable quantity of water. Something like this might happen in the admixture of bodies of porous texture. But such substances as metals, glass, and fluids, where no discontinuity of parts can be perceived, or was suspected, seem free from every chance of this kind of introduction. Lord Bacon, however, without being a naturalist or mathematician ex professo, inferred from the mobility of fluids that they consisted of discrete particles, which must have pores interposed, whatever be their figure. And if we ascribe the different densities, or other sensible qualities, to difference in size or figure of those particles, it must frequently happen that the smaller particles will be lodged in the interstices between the larger, and thus contribute to the weight of the sensible mass without increasing its bulk. He therefore suspects that mixtures will be in general less bulky than the sum of their ingredients.

Accordingly, the examination of this question was one of the first employments of the Royal Society of London, and long before its institution had occupied the attention of the gentlemen who afterwards composed it. The register of the Society's early meetings contains many experiments on this subject, with mixtures of gold and silver, of other metals, and of various fluids, examined by the hydrostatic balance of Mr. Boyle. Dr. Hooke made a prodigious number, chiefly on articles of commerce, which were unfortunately lost in the fire of London.

It was soon found, however, that Lord Bacon's conjecture had been well founded, and that bodies changed their density very sensibly in many cases. In general, it was found that bodies which had a strong chemical affinity increased in density, and that their admixture was accompanied with heat.

By this discovery it is manifest that Archimedes had not solved the problem of detecting the quantity of silver mixed with the gold in King Hiero's crown, and that the physical solution of it requires experiments made on all the kinds of matter that are mixed together. We do not find that this has been done to this day, although we may affirm that there are few questions of more importance. It is a very curious fact in chemistry, and it would be most desirable to be able to reduce it to some general laws: For instance, to ascertain what is the proportion of two ingredients which produces the greatest change of density. This is important in the science of physics, because it gives us considerable information as to the mode of action of those natural powers or forces by which the particles of tangible matter are united. If this introfusception, concentration, compenetration, or by whatever name it be called, were a mere reception of the particles of one substance into the interstices of those of another, it is evident that the greatest concentration would be observed when a small quantity of the recipient is mixed with, or disseminated through, a great quantity of the other. It is thus that a small quantity of fine sand will be received into the interstices of a quantity of small shot, and will increase the weight of the bagful without increasing its bulk. The case is nowise different when a piece of freestone has grown heavier by imbibing or absorbing a quantity of water. If more than a certain quantity of sand has been added to the small shot, it is no longer concealed. In like manner, various quantities of water may combine with a mass of clay, and increase its size and weight alike. All this is very conceivable, occasioning no difficulty.

But this is not the case in any of the mixtures we are now considering. In all these, the first additions of either of the two substances produce but an inconsiderable change of general density; and it is in general most remarkable, whether it be condensation or rarefaction, when the two ingredients are nearly of equal bulk. We can illustrate even this difference, by reflecting on the imbibition of water by vegetable solids, such as timber. Some kinds of wood have their weight much more increased than their bulk; other kinds of wood are more enlarged in bulk than in weight. The like happens in grains. This is curious, and shows in the most unquestionable manner that the particles of bodies are not in contact, but are kept together by forces which act at a distance. For this distance between the centres of the particles is most evidently susceptible of variation; and this variation is occasioned by the introduction of another substance, which, by acting on the particles by attraction or repulsion, diminishes or increases their mutual actions, and makes new distances neces- necessary for bringing all things again into equilibrium.

We refer the curious reader to the ingenious theory of the Abbé Bofcovich for an excellent illustration of this subject (Theor. Phil. Nat. § de Solutione Chymica).

This question is no less important to the man of business. Till we know the condensation of those metals by mixture, we cannot tell the quantity of alloy in gold and silver by means of their specific gravity; nor can we tell the quantity of pure alcohol in any spirituous liquor, or that of the valuable salt in any solution of it.

For want of this knowledge, the dealers in gold and silver are obliged to have recourse to the tedious and difficult test of the assay, which cannot be made in all places or by all men. It is therefore much to be wished, that some persons would institute a series of experiments in the most interesting cases; for it must be observed, that this change of density is not always a small matter; it is sometimes very considerable and paradoxical. A remarkable instance may be given of it in the mixture of brass and tin for bells, great guns, optical speculums, &c. The specific gravity of cast brass is nearly 8.066, and that of tin is nearly 7.363. If two parts of brass be mixed with one part of tin, the specific gravity is 8.917; whereas, if each had retained its former bulk, the specific gravity would have been only 7.793

\[ \frac{2 \times 8.066 + 7.363}{3} \]

A mixture of equal parts should have the specific gravity 7.684; but it is 8.441. A mixture of two parts tin with one part brass, instead of being 7.577, is 8.027.

In all these cases there is a great increase of specific gravity, and consequently a great condensation of parts or contraction of bulk. The first mixture of eight cubic inches of brass, for instance, with four cubic inches of tin, does not produce 12 cubic inches of bell-metal, but only 10½ nearly, having shrunk ¼. It would appear that the distances of the brass particles are most affected, or perhaps it is the brass that receives the tin into its pores; for we find that the condensations in these mixtures are nearly proportional to the quantities of the brass in the mixtures. It is remarkable that this mixture with the lightest of all metals has made a composition more heavy and dense than brass can be made by any hammering.

The most remarkable instance occurs in mixing iron with platinum. If 10 cubic inches of iron are mixed with 1½ of platinum, the bulk of the compound is only 9½ inches. The iron therefore has not simply received the platinum into its pores; its own particles are brought nearer together. There are similar results in the solution of turbid mineral, and of some other salts, in water. The water, instead of rising in the neck of the vessel, when a small quantity of the salt has been added to it, sinks considerably, and the two ingredients occupy less room than the water did alone.

The same thing happens in the mixture of water with other fluids and different fluids with each other: But we are not able to trace any general rule that is observed with absolute precision. In most cases of fluids the greatest condensation happens when the bulks of the ingredients are nearly equal. Thus, in the mixture of alcohol and water, we have the greatest condensation when 16½ ounces of alcohol are mixed with 20 ounces of water, and the condensation is about ¼ of the whole bulk of the ingredients. It is extremely various in different substances, and no classification of them can be made in this respect.

A dissertation has been published on this subject by Dr Hahn of Vienna, intitled De Efficiis Mixtionis in mutandis Corporum Voluminibus, in which all the remarkable instances of the variation of density have been collected. All that we can do (as we have no directing principle) is to record such instances as are of chief importance, being articles of commerce.

The first that occurs to us is the mixtures of alcohol and water in the composition of spirituous liquors. This has been considered by many with great care. The most scrupulous examination of this, or perhaps of any mixture, has been lately made by Dr Blagden (now Sir Charles Blagden) of the Royal Society, on the requisition of the Board of Excise. He has published an account of the examination in the Philosophical Transactions of London in 1791 and 1792. We shall give an account of it under the article Spirituous Liquors; and at present only select one column, in order to show the condensation. The alcohol was almost the strongest that can be produced, and its specific gravity, when of the temperature 62°, was 0.825. The whole mixtures were of the same temperature.

Column 1. contains the pounds, ounces, or other measures by weight, of alcohol in the mixture. Column 2. contains the pounds or ounces of water. Column 3. is the sum of the bulks of the ingredients, the bulk of a pound or ounce of water being accounted 1. Column 4. is the observed specific gravity of the mixture, taken from Dr Blagden's dissertation. Column 5. is the specific gravity which would have been observed if the ingredients had each retained its own specific gravity. This we calculated by dividing the sum of the two numbers of the first and second columns by the corresponding number of the third. Column 6. is the difference of column 4. and column 5. and exhibits the condensation.

| A. | W. | Volume | Sp. Grav' | Sp. Grav' | Condensation | |----|----|--------|-----------|-----------|--------------| | | | | Observed | Calculated| | | 20 | 0 | 24.2424 | 0.8250 | 0.8250 | 00 | | 20 | 1 | 25.2424 | 0.8360 | 0.8320 | 40 | | 20 | 2 | 26.2424 | 0.8457 | 0.8383 | 74 | | 20 | 3 | 27.2424 | 0.8543 | 0.8443 | 100 | | 20 | 4 | 28.2424 | 0.8621 | 0.8498 | 123 | | 20 | 5 | 29.2424 | 0.8692 | 0.8549 | 143 | | 20 | 6 | 30.2424 | 0.8757 | 0.8597 | 160 | | 20 | 7 | 31.2424 | 0.8817 | 0.8642 | 175 | | 20 | 8 | 32.2424 | 0.8872 | 0.8684 | 188 | | 20 | 9 | 33.2424 | 0.8923 | 0.8724 | 199 | | 20 | 10 | 34.2424 | 0.8971 | 0.8761 | 216 | | 20 | 11 | 35.2424 | 0.9014 | 0.8796 | 218 | | 20 | 12 | 36.2424 | 0.9055 | 0.8829 | 226 | | 20 | 13 | 37.2424 | 0.9093 | 0.8860 | 233 | | 20 | 14 | 38.2424 | 0.9129 | 0.891 | 238 | | 20 | 15 | 39.2424 | 0.9162 | 0.8949 | 243 | | 20 | 16 | 40.2424 | 0.9193 | 0.8984 | 247 | | 20 | 17 | 41.2424 | 0.9223 | 0.8971 | 252 | | 20 | 18 | 42.2424 | 0.9255 | 0.8996 | 254 | | 20 | 19 | 43.2424 | 0.9276 | 0.9019 | 257 | | 20 | 20 | 44.2424 | 0.9300 | 0.9044 | 259 | | 19 | 20 | 43.303 | 0.9325 | 0.9063 | 262 | It is to be remarked, that the condensation is greatest when 16½ ounces of alcohol have been added to 20 of water, and the condensation is nearly ⅓rd of the computed density. Since the specific gravity of alcohol is 0.825, it is evident that 16½ ounces of alcohol and 20 ounces of water have equal bulks. So that the condensation is greatest when the substances are mixed in equal volumes; and 18 gallons of alcohol mixed with 18 gallons of water will produce not 36 gallons of spirits, but 35 only.

We may also observe, that this is the mixture to which our revenue-laws refer, declaring it to be one to six or one in seven under proof, and to weigh 7 pounds 13 ounce per gallon. This proportion was probably selected as the most easily composed, viz. by mixing equal measures of water and of the strongest spirit which the known processes of distillation could produce. Its specific gravity is 0.939 very nearly.

We must consider this elaborate examination of the mixture of water and alcohol as a standard series of experiments, to which appeal may always be made, whether for the purposes of science or of trade. The regularity of the progression is so great, that in the column which we have examined, viz. that for temperature 65°, the greatest anomaly does not amount to one part in six thousand. The form of the series is also very judiciously chosen for the purposes of science. It would perhaps have been more directly stereometrical had the proportions of the ingredients been stated in bulks, which are more immediately connected with density. But the author has assigned a very cogent reason for his choice, viz. that the proportion of bulks varies by a change of temperature, because the water and spirits follow different laws in their expansion by heat.

This is a proper opportunity for taking notice of a mistake which is very generally made in the conclusions drawn from experiments of this kind. Equal additions of the spirit or water produce a series of specific gravities, which decrease or increase by differences continually diminishing. Hence it is inferred that there is a contraction of bulk. Even Dr Lewis, one of our most accomplished naturalists, advances this position, in a dissertation on the pot-ash of America; and it considerably affects his method for estimating the strength of the pot-ash leys. But that it is a mistake, appears plausibly from this, that although we add for ever equal quantities of the spirits, we shall never produce a mixture which has as small a specific gravity as alcohol. Therefore the series of successive gravities must approximate to this without end, like the ordinates of a hyperbolic curve referred to its asymptote.

That this may appear in the most general terms, let \( w \) represent the weight of the constant quantity of water in the mixture, and let \( a \) be the weight of the small addition of spirits. Also let \( w \) represent the bulk of this quantity of water, and \( b \) the bulk of the small addition of alcohol. The weight of the mixture is \( w + a \), and its bulk is \( w + b \), and its specific gravity is \( \frac{w + a}{w + b} \).

If we now add a second equal quantity of spirits, the weight will be \( w + 2a \), and if the spirit retains its density unchanged, the bulk will be \( w + 2b \), and the specific gravity is \( \frac{w + 2a}{w + 2b} \); and after any number \( m \) of such equal additions of spirits, the specific gravity will be \( \frac{w + ma}{w + mb} \). Divide the numerator of this fraction by its denominator, and the quotient or specific gravity will be \( 1 + \frac{m(a - b)}{w + mb} \). This consists of the constant part 1, and the variable part \( \frac{m(a - b)}{w + mb} \). We need attend only to this part. If its denominator were constant, it is plain that the successive specific gravities would have equal differences, each being \( \frac{a - b}{w + mb} \), because \( m \) increases by the continual addition of an unit, and \( a - b \) is a constant quantity. But the denominator \( w + mb \) continually increases, and therefore the value of the fraction \( \frac{a - b}{w + mb} \) continually diminishes.

Therefore the gradual diminution of the increments or decrements of specific gravity, by equal additions of one ingredient to a constant measure of the other, is not of itself an indication of a change of density of either of the ingredients; nor proves that in very diluted mixtures a greater proportion of one ingredient is absorbed or lodged in the interstices of the other, as is generally imagined. This must be ascertained by comparing each specific gravity with the gravity expressed by \( 1 + \frac{ma - wb}{w + mb} \).

This series of specific gravities resembles such a numerical series as the following, 1; . . . . . . ; 1.156; 1.163; 1.169; &c. the terms of which also consist of the constant integer 1, and the decimal fractions 0.156; 0.163; 0.169; &c. The fraction \( \frac{ma - wb}{w + mb} \) expresses this decimal part. Call this \( d \), or make \( d = \frac{ma - wb}{w + mb} \).

This will give us \( b = \frac{ma - wb}{w(1 + d)} \). Now \( a \) is the weight of the added ingredient, and \( d \) is the variable part of the specific gravity observed; and thus we learn whether... Specific ther b; the bulk of the added ingredient, suffers any change. We shall have occasion by and by to resume the consideration of this question, which is of the first moment in the theory of specific gravities, and has great influence in many transactions of commerce.

This series of specific gravities is not so well fitted for commercial transactions. In these usual questions is, how many gallons of alcohol is there in a cask, or some number of gallons of spirit? and it is more directly answered by means of a table, formed by mixing the ingredients in aliquant parts of one constant bulk. The following table, constructed from the experiments of Mr Briffon of the academy of Paris, and published in the Memoirs for 1769, is therefore inserted.

| W. | A. | Density observed. | Density computed. | Condensation. | Bulk of 10,000 grains. | |----|----|------------------|------------------|--------------|----------------------| | 0 | 16 | 0.8371 | 0.8371 | | 1,0000 | | 1 | 15 | 0.8527 | 0.8473 | 63 | 0.9937 | | 2 | 14 | 0.8674 | 0.8575 | 115 | 0.9885 | | 3 | 13 | 0.8815 | 0.8677 | 157 | 0.9844 | | 4 | 12 | 0.8947 | 0.8778 | 189 | 0.9811 | | 5 | 11 | 0.9075 | 0.8880 | 214 | 0.9786 | | 6 | 10 | 0.9199 | 0.8982 | 235 | 0.9765 | | 7 | 9 | 0.9317 | 0.9084 | 251 | 0.9749 | | 8 | 8 | 0.9427 | 0.9186 | 256 | 0.9744 | | 9 | 7 | 0.9519 | 0.9287 | 243 | 0.9737 | | 10 | 6 | 0.9598 | 0.9389 | 217 | 0.9783 | | 11 | 5 | 0.9674 | 0.9491 | 189 | 0.9811 | | 12 | 4 | 0.9733 | 0.9593 | 144 | 0.9856 | | 13 | 3 | 0.9791 | 0.9695 | 99 | 0.9901 | | 14 | 2 | 0.9852 | 0.9796 | 57 | 0.9943 | | 15 | 1 | 0.9919 | 0.9898 | 21 | 0.9979 | | 16 | | 1,0000 | 1,0000 | | 1,0000 |

In this table the whole quantity of spirituous liquor is always the same. The first column is the number of measures (gallons, pints, inches, &c.) of water in the mixture; and column 2d gives the measures of alcohol. Column 3d is the specific gravity which was observed by Mr Briffon. Column 4th is the specific gravity which would have been observed if the spirits, or water, or both, had retained their specific density unchanged. And the 5th column marks the augmentation of specific gravity or density in parts of 10,000. A 6th column is added, showing the bulk of the 16 cubic measures of the two ingredients. Each measure may be conceived as the 16th part of 10,000, or 625; and we may suppose them cubic inches, pints, gallons, or any solid measure.

This table scarcely differs from Sir Charles Blagden's; and the very small difference that may be observed, arises from Mr Briffon's having used an alcohol not to completely rectified. Its specific gravity is 0.8371, whereas the other was only 0.8250.

Here it appears more distinctly that the condensation is greatest when the two ingredients are of equal bulk.

Perhaps this series of specific gravities is as declarative as the other, whether or not there is a change of density induced on either of the ingredients. The whole bulk being always the same, it is plain that the successive equal additions to one of the ingredients is a successive equal abstraction of the other. The change produced, therefore, in the weight of the whole, is the difference between the weight of the ingredient which is taken out and the weight of the equal measure of the other which supplies its place. Therefore, if neither ingredient changes its density by mixture, the weights of the mixtures will be in arithmetical progression. If they are not, there is a variation of density in one or both the ingredients.

We see this very clearly in the mixtures of water and alcohol. The first specific gravity differs from the second by 156, and the last differs from the preceding by no more than 81. Had neither of the densities changed, the common difference would have been 102. We observe also, that the augmentation of specific gravity, by the successive addition of a measure of water, grows less and less till 12 measures of water is mixed with 4 of alcohol, when the augmentation is only 58, and then it increases again to 81.

It also appears, that the addition of one measure of water to a quantity of alcohol produces a greater change of density than the mixture of one measure of alcohol to a quantity of water. Hence some conclude, that the water disappears by being lodged in the interstices of the spirit. But it is more agreeable to the justest notions which we can form of the internal constitution of tangible bodies to suppose that the particles of water diminish the distances between the particles of alcohol by their strong attractions, and that this diminution (exceedingly minute in itself) becomes sensible on account of the great number of particles whose distances are thus diminished. This is merely a probability founded on this, that it would require a much greater diminution of distances if it was the particles of water which had their distances thus diminished. But the greater probability is, that the condensation takes place in both.

We have been so particular in our consideration of this mixture, because the law of variation of density has, in this instance, been ascertained with such precision by the elaborate examination of Sir Charles Blagden, so that it may serve as an example of what happens in almost every mixture of bodies. It merits a still farther discussion, because it is intimately connected with the action of the corpuscular forces; and an exact knowledge of the variations of distance between the particles will go far to ascertain the law of action of these forces. But the limits of a Work like this will not permit us to dwell longer on this subject. We proceed therefore to give another useful table.

The vitriolic or sulphuric acid is of extensive use in manufactures under the name of oil of vitriol. Its value depends entirely on the saline ingredient, and the water is merely a vehicle for the acid. This, being much denser than water, affects its specific gravity, and thus gives us a method of ascertaining its strength.

The strongest oil of vitriol that can be easily manufactured contains 612½ grains of dry acid, united with 387½ grains of water, which cannot be separated from it by distillation, making 1000 grains of oil of vitriol. Its specific gravity in this state is 1.877.

The following table shows its specific gravity at the temperature 55°, when diluted by the successive addition of parts of water by weight. Here is observed a much greater condensation than in the mixture of alcohol and water. But we cannot assign the proportion of ingredients which produces the greatest condensation; because we cannot, in any case, say what is the proportion of the saline and watery ingredients. The strongest oil of vitriol is already a watery solution; and it is by a considerable and uncertain detour that Mr Kirwan has assigned the proportion of 612 and 388 nearly. If this be the true ratio, it is unlikely every other solution that we are acquainted with; for in all solutions of salts, the salt occupies less room in its liquid form than it did when solid; and here it would be greatly the reverse.

This solution is remarkable also for the copious emergence of heat in its dilutions with more water. This has been ascribed to the great superiority of water in its capacity for heat; but there are facts which render this very doubtful. A vessel of water, and another of oil of vitriol, being brought from a cold room into a warm one, they both imbibe heat, and rise in their temperature; and the water employs nearly the same time to attain the temperature of the room.

Aquafortis or nitrous acid is another fluid very much employed in commerce; so that it is of importance to ascertain the relation between its saline strength and its specific gravity. We owe also to Mr Kirwan a table for this purpose.

The most concentrated state into which it can easily be brought is such, that 1000 grains of it consists of 563 grains of water and 437 of dry acid. In this state its specific gravity is 1.557. Let this be called nitrous acid.

There is not the same uniformity in the densities of this acid in its different states of dilution. This seems owing to the variable proportion of the deleterious and vital air which compose this acid. It is more dense in proportion as it contains more of the latter ingredient.

The proportions of the aeriform ingredients of the muriatic acid are very variable, and to little under our command, that we cannot frame tables of its specific gravity which would enable us to judge of its strength.

It is a general property of these acids, that they are more expandible by heat as they are more concentrated.

There is another class of fluids which it would be of great consequence to reduce to some rules with respect to specific gravity, namely, the solutions of salts, gums, and resins. It is interesting to the philosopher to know in what manner salts are contained in these watery solutions, and to discover the relation between their strength and density; and to the man of business it would be a most desirable thing to have a criterion of the quantity of salt in any brine, or of extractible matter in a decoction. It would be equally desirable to those who are to purchase them as to those who manufacture or employ them. Perhaps we might ascertain in this way the value of sugar, depending on the quantity of sweetening matter which it contains; a thing which at present rests on the vague determination of the eye or palate. It would therefore be doing a great service to the public, if some intelligent person would undertake a train of experiments with this view. Accuracy alone is required; and it may be left to the philosophers to compare the facts, and draw the consequences respecting the internal arrangement of the particles.

One circumstance in the solution of salts is very general; and we are inclined, for serious reasons, to think it universal: this is a diminution of bulk. This indeed in some salts is inconsiderable. Sedative salt, for instance, hardly shows any diminution, and might be considered as an exception, were it not the single instance. This circumstance, and some considerations connected with our notions of this kind of solution, dispose us to think that this salt differs in contraction from others only in degree, and that there is some, though it was not sensible, in the experiments hitherto made.

These experiments, indeed, have not been numerous. Those of Mr Achard of Berlin, and of Dr Richard Watson of Cambridge, are perhaps the only ones of which we have a descriptive narration, by which we can judge of the validity of the inferences drawn from them. The subject is not susceptible of much accuracy; for salts in their solid form are seldom free from cavities and thorny interstices, which do not admit the water on their first immersion, and thereby appear of greater bulk when we attempt to measure their specific gravity by weighing them in fluids which do not dissolve them, such as spirits of turpentine. They also attach to themselves, with considerable tenacity, a quantity of atmospheric air, which merely adheres, but makes no part of their composition. This escapes in the act of solution, being set at liberty by the stronger affinity of the water. Salt gem, however, and a few others, may be very accurately measured; and in these instances the degree of contraction is very constant.

The following experiments of Dr Watson appear to us the most instructive as to this circumstance. A glass vessel was used, having a slender cylindrical neck, and holding 67 ounces of pure water when filled to a certain The neck above this mark had a scale of equal parts pasted on it. It was filled to the mark with water. Twenty-four pennyweights of salt were thrown into it as speedily as possible, and the bulk of the salt was measured by the elevation of the water. Everything was attended to which could retard the immediate solution, that the error arising from the solution of the first particles, before the rest could be put in, might be as small as possible; and in order that both the absolute bulk and its variations might be obtained by some known scale, 24 pennyweights of water were put in. This raised the surface 58 parts of the scale. Now we know exactly the bulk of 24 pennyweights of pure water. It is 2,275 cubic inches; and thus we obtain every thing in absolute measures: And by comparing the bulk of each salt, both at its first immersion and after its complete solution, we obtain its specific gravity, and the change made on it in passing from a solid to a fluid form. The following table is an abstract of these experiments. The first column of numbers is the elevation of the surface immediately after immersion; the second gives the elevation when the salt is completely dissolved; and the third and fourth columns are the specific gravities of the salts in these two states.

| Twenty-four Pennyweights | I | II | III | IV | |--------------------------|-----|-----|-----|-----| | Water | 58 | | | | | Glauber's salt | 42 | 36 | 1,380| 1,611| | Mild volatile alkali | 40 | 33 | 1,450| 1,787| | Sal ammoniac | 40 | 39 | 1,450| 1,487| | Refined white sugar | 39 | 36 | 1,487| 1,611| | Coarse brown sugar | 39 | 36 | 1,487| 1,611| | White sugar candy | 37 | 36 | 1,567| 1,611| | Lymington Glauber's salt | 35 | 29 | 1,657| 2,000| | Terra foliata tartari | 37 | 30 | 1,567| 1,933| | Rochelle salt | 33 | 28 | 1,757| 2,071| | Alum not quite dissolved | 33 | 28 | 1,757| 2,661| | Borax not one-half dissolved in two days | 33 | 31 | 1,757| | | Green vitriol | 32 | 26 | 1,812| 2,230| | White vitriol | 30 | 24 | 1,933| 2,416| | Nitre | 30 | 21 | 1,933| 2,766| | Sal gem from Northwich | 27 | 17 | 2,143| 3,411| | Blue vitriol | 26 | 20 | 2,230| 2,900| | Pearl ashes | 25 | 10 | 2,320| 5,800| | Tart. vitriolatus | 22 | 11 | 2,636| 5,272| | Green vitriol calcined to white | 22 | 11 | 2,636| 5,272| | Dry salt of tartar | 21 | 13 | 2,761| 4,461| | Balliet sea-salt | 19 | 15 | 3,052| 3,866| | Corrosive sublimate | 14 | 10 | 4,142| 3,800| | Turbith mineral | 9 | 0 | 6,444| |

The inspection of this list naturally suggests two states of the case as particularly interesting to the philosopher studying the theory of solution. The first state is when the lixivium approaches to saturation. In the very point of saturation any addition of salt retains its bulk unchanged. In diluted brines, we shall see that the density of the fluid salt is greater, and gradually diminishes as we add more salt. It is an important question, whether this diminution goes on continually, till the fluid density of the salt is the same with its solid density? or, whether there is an abrupt passage from some degree of the one to the fixed degree of the other, as we observe in the freezing of iron, the setting of stucco, and some other instances?

The other interesting state is that of extreme dilution, when the differences between the successive densities bear a great proportion to the densities themselves, and thus enable the mathematician to ascertain with some precision the variations of corporeal force, in consequence of a variation of distance between the particles. The sketch of an investigation of this important question given by Bozovich, in his Theory of Natural Philosophy, is very promising, and should incite the philosophical chemist to the study. The first thing to be done is to compare the law of specific gravity; that is, the relation between the specific gravity and quantity of salt held in solution.

Wishing to make this work as useful as possible, we have searched for experiments, and trains of experiments, on the density of the many brines which make important articles of commerce; but we were mortified by the scantiness of the information, and disappointed in our hopes of being able to combine the detached observations, suited to the immediate views of their authors, in such a manner as to deduce from them scales (as they may be called) of their strength. We rarely found these detached observations attended with circumstances which would connect them with others; and there was frequently such a discrepancy, nay opposition, in series of experiments made for ascertaining the relation between the density and the strength, that we could not obtain general principles which enable us to construct tables of strength a priori.

Mr Lambert, one of the first mathematicians and philosophers of Europe, in a dissertation in the Berlin Memoirs (1762), gives a narration of experiments on the brines of common salt, from which he deduces a very great condensation, which he attributes to an absorption in the weak brines of the salt, or a lodgement of its particles in the interstices of the particles of water. Mr Achard of the same academy, in 1785, gives a very great list of experiments on the bulks of various brines, made in a different way, which show no such introspection; and Dr Watson, formerly regius professor of chemistry at Cambridge, and now bishop of Landaff, thinks this confirmed by experiments which he narrates in his Chemical Essays. We see great reason for hesitating our assent to either side, and do not think the experiments decisive. We incline to Mr Lambert's opinion; for this reason, that in the successive dilutions of oil of vitriol and aquafortis there is a most evident and remarkable condensation. Now what are these but brines, of which we have not been able to get the saline ingredient in a separate form? The experiments of Mr Achard and Dr Watson were made in such a way that a single grain in the measurement bore too great a proportion to the whole change of specific gravity. At the same time, some of Dr Watson's are so simple in their nature that it is very difficult to withhold the assent.

In this state of uncertainty, in a subject which seems to us to be of public importance, we thought it our duty to undertake a train of experiments to which recourse may always be had. Works like this are seldom considered as sources of original information; and it is thought sufficient when the knowledge... Specific gravity already discussed is judiciously compiled. But a due respect for the public, and gratitude for the very honourable reception hitherto given to our labours, induce us to exert ourselves with honest zeal to merit the continuance of public favour. We assure our readers that the experiments were made with care, and on quantities sufficiently large to make the unavoidable irregularities in such cases quite insignificant. The law of density was ascertained in each substance in two ways. We dissolved different portions of salt in the same quantity of water, and examined the specific gravity of the brine by weighing it in a vessel with a narrow neck. The portions of salt were each of them one-eighth of what would make a nearly saturated solution of the temperature 55°. We did not make the brine stronger, that there might be no risk of a precipitation in form of crystals. We considered the specific gravities as the ordinates of a curve, of which the abscissae were the numbers of ounces of dry salt contained in a cubic foot of the brine. Having thus obtained eight ordinates corresponding to 1, 2, 3, 4, 5, 6, 7, and 8 portions of salt, the ordinates or specific gravities for every other proportion of salt were laid by the usual methods of interpolation.

The other method was, by first making a brine nearly saturated, in which the proportion of salt and water was exactly determined. We then took out one-eighth of the brine, and filled up the vessel with water, taking care that the mixture should be complete; for which purpose, besides agitation, the diluted brine was allowed to remain 24 hours before weighing. Taking out one-eighth of the brine also takes out one-eighth of the salt; so that the proportion of salt and water in the diluted brine was known. It was now weighed, and thus we determined the specific gravity for a new proportion of salt and water.

We then took out one-seventh of the brine. It is evident that this takes out one-eighth of the original quantity of salt; an abstraction equal to the former. We filled the vessel with water with the same precautions; and in the same manner we proceeded till there remained only one-eighth of the original quantity of salt.

The specific gravities by these two methods agreed extremely well. In the very deliquescent salts the first method exhibited some small irregularities, arising from the unequal quantities of water which they had imbibed from the atmosphere. We therefore confined most in the experiments made with diluted brines.

That the reader may judge of the authority of the tables which we shall insert, we submit to his inspection one series of experiments.

Two thousand one hundred and eighty-eight grains of very pure and dry (but not decrepitated) common salt, prepared in large crystals, were dissolved in 6562 grains of distilled water of the temperature 55°. A small matras with a narrow neck, which held 4200 grains of distilled water, was filled with this brine. Its contents weighed 5027 grains. Now \( \frac{6562 + 2188}{2188} = 5027 : 125675 \). Therefore the bottle of brine contained 125675 grains of salt dissolved in 377025 grains of water. Its specific gravity is \( \frac{5027}{4200} \), or 1.196905; and a cubic foot of brine weighs 1196.9 ounces avoirdupois. Also \( \frac{5027}{125675} = 0.040279 \).

Thus, by repeated abstraction of brine, so as always to take out \( \frac{1}{8} \)th of the salt contained in one constant bulk, we have obtained a brine consisting of 157 grains of salt united with 43 3 - 157, or 4156 grains of water. Its specific gravity is \( \frac{4313}{4200} = 1.0279 \), and a cubic foot of it weighs 1028 ounces, and contains 37 4 ounces of dry salt. In like manner may the specific gravity, the weight of a cubic foot, and the salt it contains, be estimated for the intermediate brines.

When these eight quantities of salt contained in a cubic foot are made the abscissae, and the weights of the cubic foot of brine are the corresponding ordinates, the curve... belief of ghosts may be easily deduced from the opinions entertained respecting a future state. These opinions are founded on that essential doctrine of natural religion, that there is another world in which men shall exist when death has removed them hence. This doctrine has been universally received both by savage and civilized nations; but, as might be expected, men have formed very different sentiments concerning the nature of a future state, of the situation and employments of departed spirits, according to the degree of knowledge which they possessed. But the general opinion in ancient and rude nations was, that departed spirits retained the same external appearance, the same passions and principles as before. Nothing therefore was more natural than the opinion, that they might occasionally revisit this world, from an anxious desire to alleviate the sufferings of those beloved friends and relations whom they had left behind them, or to communicate from the unseen world what might be important to their welfare. Upon such an errand did Creusa appear to Æneas. The apparition of the ghosts of murderers is easily explained upon the same general principles. The remorse and horror of mind which the murderer feels are supposed to haunt him in the other world, and to render his situation there intolerable (especially if the murder was never detected and punished), till he return and give information against himself. In this way, then, we think it highly probable the belief of spectres has originated. But many other causes concur to confirm and propagate this belief. There are, imperfect vision united with fear, dreams, opium, diseases, drunkenness, and artifice.

1. Indistinct vision is one source of apparitions, especially when the mind is under the influence of fear. It is well known, that the sense of seeing conveys no idea of distance till improved by experience and observation; and how we come at length to distinguish objects at a distance from those that are near, has been explained in another place (see Metaphysics, no 50).

In the day-time we seldom commit mistakes, because we know the object at which we look; but at night, when we see objects obscurely, and know not what they are, we have no distinct idea either of their distances or of their magnitude. We may mistake a bush that is near us for a tree at a distance; or if the imagination be under the influence of fear, it will easily convert it into a gigantic figure. "It is generally asserted (says Buffon) that these figures exist only in the imagination; yet they may have a real existence in the eye; for whenever we have no other mode of judging of an unknown object but by the angle it forms in the eye, its magnitude will uniformly increase in proportion to its propinquity. If it appears, when at the distance of 20 or 30 paces, to be only a few feet high, its height, when within two or three feet of the eye, will be many fathoms. An object of this kind must naturally excite terror and astonishment in the spectator, till he approaches and recognizes it by actual feeling; for the moment a man knows an object, the gigantic appearance it assumed in the eye instantly diminishes, and its apparent magnitude is reduced to its real dimensions. But if, instead of approaching such an object, the spectator flies from it, he can have no other idea of it but from the image which it formed in his eye; and, in this case, he may affirm with truth that he saw an object terrible in its aspect, and enormous in its size. Thus the notions concerning spectres is founded in nature, and depend not, as some philosophers affirm, upon the imagination alone."

In addition to these observations of Buffon, we may take notice, that objects are always magnified in a fog; so that when a fog happens in the night-time, objects may be magnified to an enormous size. But, at any rate, whether there be fog in the night or not, there is such a great analogy between darkness and a fog, that if the latter deceive us with respect to the size of objects, the former will also deceive us. The writer of this article was passing the Frith of Forth at Queensferry, near Edinburgh, one morning which was extremely foggy. Though the water be only two miles broad, the boat did not get within sight of the southern shore till it approached very near it. He then saw to his great surprise a large perpendicular rock, where he knew the shore was low and almost flat. As the boat advanced a little nearer, the rock seemed to split perpendicularly into portions, which separated at a little distance from one another. He next saw these perpendicular divisions move; and upon approaching a little nearer, found it was a number of people standing on the beach, waiting the arrival of the ferry-boat.

2. Dreams are another fertile source of apparitions. It is well known to every person, that while the mind is under the influence of a dream it considers it as much a reality as it does any particular action while awake. Now if a person of a weak superstitious mind should have a very lively dream, which interests his passions, particularly the passion of fear, it may make so deep an impression, that he may be firmly convinced that he has actually seen with his eyes what has only passed before his imagination (See Apparition) (a). We shall here tell a story, by way of illustration, which we have received on unquestionable authority. An East Indian captain had an honest faithful servant named John, for whom he had a great regard. John died, if we recollect right, on a voyage from England to the East Indies during a French war. As the ship approached the place of its destination the captain had a dream, in which John appeared to him, and earnestly besought him not to fail to the port for which he was bound, as it was in the hands of the French. The captain, though not addicted to superstition, thought it prudent to follow this admonition; and after landing at a different port, he was informed that the place to which he had intended to steer was, according to the information of the dream, captured by the French. On the voyage home, the captain had a second dream, in which John again appeared to him, and gave him no

(a) When the thoughts are much troubled, and when a person sleeps without the circumstances of going to bed, or putting off his clothes, as when he nods in his chair, it is very difficult, as Hobbes remarks, to distinguish a dream from a reality. On the contrary, he that composes himself to sleep, in case of any uncouth or absurd fancy, easily suspects it to have been a dream.—Leviathan, par. i. c. i. Specre, tice that he should soon die, and that the ship should be taken in the mouth of the Channel by the French. Next morning the captain called his first mate, told him his dream, which he believed was prophetic, and delivered his papers, that he might take proper care of them after his decease. Every thing happened exactly as the dream had foretold; the captain died, and the vessel was taken by a French man of war in the mouth of the Channel. This dream, wonderful as it appears, is easily explained. In the voyage out to India, nothing was more natural than that the captain should sometimes be thinking, that amidst the various chances of war, the port to which he was bound might be taken; perhaps it was a place of consequence, which the French might be eager to possess. The captain being accustomed to resolve these thoughts in the daytime, they would naturally return at night; the regret which he felt for the loss of a faithful servant might mingle with his apprehensions, and thus produce the dream. Perhaps the advice was such as John would have given had he been alive. It is equally easy to explain the cause of the dream in the palatial home. The captain, we are told, was very ill, and thought himself dying, at the very time he had the second dream, and therefore did not expect to reach England. This part of the dream, then, was only his own thoughts, delivered by his servant. As to the other part, that his ship should be taken in the mouth of the Channel, it may be thought unaccountable how the very place should be foreseen. But we must recollect, that the mouth of the Channel, being over against the coast of France, was by far the most dangerous place in the whole passage; and that, therefore, the captain had more reason to be afraid of losing his ship there than in any other place. The use which we mean to make of this story is this: Had the captain been a man of a weak mind, he would certainly have considered the dream as a reality, and believed, that instead of having dreamed of the things on which his imagination had dwelled, he had actually seen his servant return from the dead, and heard him deliver the message. But, on the other hand, the captain, though he believed the dream was prophetic, mentioned it without any signs of fear; and no man of courage and reflection ever sees an apparition. This sight is reserved for the weak, the timid, and superstitious. Of this many instances might be mentioned.

2. Spectres are sometimes also occasioned by opium. Gaffendi the philosopher found a number of people going to put a man to death for having intercourse with the devil; a crime which the poor wretch readily acknowledged. Gaffendi begged of the people that they would permit him first to examine the wizard before putting him to death. They did so; and Gaffendi, upon examination, found that the man firmly believed himself guilty of this impossible crime. He even offered to Gaffendi to introduce him to the devil. The philosopher agreed; and when midnight came, the man gave him a pill, which he said it was necessary to swallow before setting off. Gaffendi took the pill, but gave it to his dog. The man having swallowed his, fell into a profound sleep; during which he seemed much agitated by dreams. The dog was affected in a similar manner. When the man awoke, he congratulated Gaffendi on the favourable reception he had met with from his sable highness. It was with difficulty Gaffendi convinced him that the whole was a dream, the effect of soporific medicines, and that he had never stirred from one spot during the whole night.

4. That diseases, especially the nightmare, the hypochondria, hysterical passion, and madness, are another source of spectres, we have the strongest reason to affirm. Persons subject to the nightmare often imagine that they see spectres. This is still more the case with hypochondriac and hysteric persons, and those who are in any degree deranged in their intellects. A fact which fell within the observation of the writer of this article will both prove and illustrate this assertion. In a village in one of the midland counties of Scotland, lived a widow distinguished among her neighbours for decency of manners, integrity, and respect for religion. She affirmed, that for several nights together she had heard a supernatural voice exclaiming aloud, Murder! murder! This was immediately reported through the neighbourhood; all were alarmed, and looked around them with solicitude for the detection of the murder which they supposed to have been committed; and it was not long till a discovery seemed actually to be made. It was reported, that a gentleman, who had relations at no great distance, and had been residing in the West Indies, had lately arrived with a considerable fortune; that he had lodged in an inn about three miles off; and that he had afterwards been seen entering a house in the village where the widow lived, from which he had never returned. It was next affirmed, that a tradesman passing the church-yard about twelve at midnight had seen four men carry a dead corpse into that cemetery. These three facts being joined together seemed perfectly to agree and to confirm one another, and all believed some horrible murder had been committed. The relations of the gentleman thought they were called upon to make inquiry into the truth of these allegations; they accordingly came first to the church-yard, where, in company with the sexton, they examined all the graves with great care, in order to discover whether any of them had been lately dug, or had the appearance of containing more than one coffin. But this search was to no purpose, for no alteration had been made upon the graves. It was next reported that the murdered man had been buried in a plantation about a mile distant from the village. As the alarm was now very general, a number of the inhabitants proposed of their own accord to explore it. They accordingly spread themselves over the wood, and searched it with care, but no grave nor new dug earth was found. The writer of this article, who was then a boy at school, was along with them. The matter did not rest here: The person who was said to have seen four men carry a dead corpse into the church-yard at midnight was summoned to appear before a meeting of the justices of the peace. Upon examination he denied any knowledge of the affair, but referred the court to another person from whom he had received his information. This person was examined, and the result was the same as the former. In short, one person had heard it from another, who had received it from a third, who had heard it from a fourth; but it had received a little embellishment from every person who repeated spectre repeated it. It turned out to be the same with Smollet's story of the three black crows, which some body was said to have vomited.

Upon inquiry at the inn where the West Indian gentleman had lodged, no such gentleman had been seen there. It was found afterwards he had never left the West Indies. Still, however, the veracity of the widow was not disputed; and some dark and secret transaction was suspected. But the whole affair was at length explained by discovering that she was somewhat deranged by melancholy. And the cries which she had at first imagined she had heard were afterwards imitated by some rough person, who was highly amused with spreading terror among the credulous.

5. Drunkenness also has the power of creating spectres. Its natural effect in most cases is to derange the understanding, to throw it off its guard, and to give full scope to that passion which has a natural disposition to gain an ascendancy; and sometimes it excites passions which scarcely seem to exist at any other time. It makes some men licentious, some furious, some all benevolence and kindness, some from being cowards it renders undaunted heroes. It seldom, if ever, excites fear; and therefore it may be thought strange that men should imagine they see ghosts when intoxicated. But it must be remarked, that the ghosts which the drunkard sees, he sees not with the same alarm and terror as men who are sober. He is not afraid of them. He has the courage to converse with them, and even to fight with them, if they give him provocation. A man returning home intoxicated, affirmed that he had met with the devil; and that after a severe encounter he had vanquished him and brought him to the ground, to which he had nailed him fast by driving his staff through his body. Next morning the staff was found stuck with great violence into a heap of turfs!

6. Many apparitions of spectres have no other origin than the artifices of the waggish or self-interested. Dr Plot, in his Natural History of Oxfordshire, relates a marvellous story, which will illustrate this afflention. Soon after the murder of King Charles I., a commission was appointed to survey the king's house at Woodstock, with the manor, park, woods, and other demesnes to that manor belonging; and one Collins, under a feigned name, hired himself as secretary to the commissioners, who, upon the 13th of October 1649, met, and took up their residence in the king's own rooms. His majesty's bed-chamber they made their kitchen, the council hall their pantry, and the presence-chamber was the place where they sat for the dispatch of business. His majesty's dining-room they made their wood yard, and floored it with the wood of the famous royal-oak from the High Park, which, that nothing might be left with the name of king about it, they had dug up by the roots, and split and bundled up into faggots for their firing. Things being thus prepared, they sat on the 16th of the same month for the dispatch of business; and in the midst of their first debate there entered a large black dog (as they thought), which made a dreadful howling, overturned two or three of their chairs, and then crept under a bed and vanished. This gave them the greater surprize, as the doors were kept constantly locked, so that no real dog could get in or out. The next day their surprize was increased, when sitting at dinner in a lower room, they heard plainly the noise of persons walking over their heads, though they well knew the doors were all locked, and there could be nobody there. Presently after they heard also all the wood of the king's oak brought by parcels into the dining-room, and thrown with great violence into the presence chamber; as also all the chairs, stools, tables, and other furniture, forcibly hurled about the room; their papers, containing the minutes of their transactions, were torn, and the ink-glass broken. When all this noise had ceased, Giles Sharp, their secretary, proposed to enter first into these rooms; and in presence of the commissioners, from whom he received the key, he opened the doors, and found the wood spread about the room, the chairs tossed about and broken, the papers torn, the ink-glass broken (as has been said), but not the least trace of any human creature, nor the least reason to suspect one, as the doors were all fast, and the keys in the custody of the commissioners. It was therefore unanimously agreed, that the power who did this mischief must have entered the room at the key-hole. The night following, Sharp the secretary, with two of the commissioners servants, as they were in bed in the same room, which room was contiguous to that where the commissioners lay, had their bed's feet lifted up to much higher than their heads, that they expected to have their necks broken, and then they were let fall at once with so much violence as shook the whole house, and more than ever terrified the commissioners. On the night of the 19th, as all were in bed in the same room for greater safety, and lights burning by them, the candles in an infant went out with a sulphurous smell, and that moment many trenchers of wood were hurled about the room, which next morning were found to be the same their honours had eaten on the day before, which were all removed from the pantry, though not a lock was found opened in the whole house. The next night they still feared worse; the candles went out as before, the curtains of their honours beds were rattled to and fro with great violence; their honours received many cruel blows and bruises, by eight great pewter-dishes and a number of wooden trenchers being thrown on their beds, which being heaved off, were heard rolling about the room, though in the morning none of them were to be seen. This night likewise they were alarmed with the tumbling down of oaken billets about their beds, and other frightful noises; but all was clear in the morning, as if no such thing happened. The next night the keeper of the king's house and his dog lay in the commissioners room, and then they had no disturbance. But on the night of the 22d, though the dog lay in the room as before, yet the candles went out, a number of brick-bats fell from the chimney into the room, the dog howled pitifully, their bed clothes were all stripped off, and their terror increased. On the 24th they thought all the wood of the king's oak was violently thrown down by their bed-fides; they counted 64 billets that fell, and some hit and shook the beds in which they lay; but in the morning none were found there, nor had the door been opened where the billet wood was kept. The next night the candles were put out, the curtains rattled, and a dreadful crack like thunder was heard; and one of the servants running in haste, thinking his master was killed, found three dozen of trenchers laid smoothly under the quilt by him. But all this was nothing to what succeeded afterwards: The 29th, about midnight, the candles went out, something walked majestically through the room, and opened and shut the windows; great stones were thrown violently into the room, some of which fell on the beds, others on the floor; and at about a quarter after one a noise was heard as of forty cannon discharged together, and again repeated at about eight minutes distance. This alarmed and raised all the neighbourhood, who coming into their honours room, gathered up the great stones, four-score in number, and laid them by in the corner of a field, where, in Dr Plot's time, who reports this story, they were to be seen. This noise, like the discharge of cannon, was heard through all the country for 16 miles round. During these noises, which were heard in both rooms together, the commissioners and their servants gave one another over for lost, and cried out for help; and Giles Sharp, snatching up a sword, had well nigh killed one of their honours, mistaking him for the spirit, as he came in his shirt from his own room to theirs. While they were together, the noise was continued, and part of the tiling of the house was stript off, and all the windows of an upper room were taken away with it. On the 30th at midnight something walked into the chamber treading like a bear; it walked many times about, then threw the warming-pan violently on the floor; at the same time a large quantity of broken glass, accompanied with great stones and horse's bones, came pouring into the room with uncommon force. These were all found in the morning to the astonishment and terror of the commissioners, who were yet determined to go on with their business. But on the first of November the most dreadful scene of all ensued: Candles in every part of the room were lighted up, and a great fire made; at midnight, the candles all yet burning, a noise like the bursting of a cannon was heard in the room, and the burning billets were tossed about by it even into their honours beds; who called Giles and his companions to their relief; otherwise the house had been burnt to the ground; about an hour after the candles went out as usual, the crack as if many cannon was heard, and many pailfuls of green slopping water were thrown upon their honours beds; great stones were also thrown in as before, the bed curtains and bedsteads torn and broken, the windows shattered, and the whole neighbourhood alarmed with the most dreadful noises; nay, the very rabbit-stealers that were abroad that night in the Warren were so terrified, that they fled for fear and left their ferrets behind them. One of their honours this night spoke, and, in the name of God, asked what it was, and why it disturbed them so? No answer was given to this; but the noise ceased for a while, when the spirit came again; and, as they all agreed, brought with it seven devils worse than itself. One of the servants now lighted a large candle, and set it in the door-way between the two chambers, to see what passed; and as he watched it, he plainly saw a hoof striking the candle and candlestick into the middle of the room, and afterwards making three scrapes over the snuff, scraped it out. Upon this the same person was so bold as to draw a sword; but he had scarce got it out when he felt another invisible hand holding it too, and pulling it from him; and at length prevailing, struck him so violently on the head with the pommel, that he fell down for dead with the blow. At this instant was heard another burst like the discharge of the broadside of each ship of war, and at about a minute or two's distance each no less than 10 more such: these shook the house so violently, that they expected every moment it would fall upon their heads. The neighbours, on this, as has been said, being all alarmed, flocked to the house in great numbers, and all joined in prayer and psalm-singing; during which the noise still continued in the other rooms, and the discharge of cannons was heard as from without, though no visible agent was seen to discharge them. But what was the most alarming of all, and put an end to their proceedings effectually, happened the next day as they were all at dinner, when a paper, in which they had signed a mutual agreement to reserve a part of the premises out of the general survey, and afterwards to share it equally amongst themselves, (which paper they had hid for the present under the earth in a pot in one corner of the room, and in which an orange-tree grew), was consumed in a wonderful manner, by the earth's taking fire with which the pot was filled, and burning violently with a blue flame, and an intolerable stench; so that they were all driven out of the house, to which they could never be again prevailed upon to return.

This wonderful contrivance was all the invention of the memorable Joseph Collins of Oxford, otherwise called Funny Joe, who having hired himself as secretary, under the name of Giles Sharp, by knowing the private traps belonging to the house, and the help of fulminic and other chemical preparations, and letting his fellow-servants into the scheme, carried on the deceit without discovery to the very last; infomuch that the late Dr Plot, in his Natural History, relates the whole for fact, and concludes in this grave manner, "That though tricks have been often played in affairs of this kind, many of the things above related are not reconcileable with juggling; such as the loud noises, beyond the power of man to make without such instruments as were not there; the tearing and breaking the beds; the throwing about the fire; the hoop treading out the candle; and the striving for the sword, and the blow the man received from the pommel of it."