ICE, in Physiology, a solid, transparent, and brittle body,
1er. body, formed of some fluid, particularly water, by means of cold.
The younger Lemery observes, that ice is only a re-establishment of the parts of water in their natural state; that the mere absence of fire is sufficient to account for this re-establishment; and that the fluidity of water is a real fusion, like that of metals exposed to the fire; differing only in this, that a greater quantity of fire is necessary to the one than the other. Galileo was the first that observed ice to be lighter than the water which composed it; and hence it happens, that ice floats upon water, its specific gravity being to that of water as eight to nine. This rarefaction of ice seems to be owing to the air-bubbles produced in water by freezing; and which, being considerably large in proportion to the water frozen, render the body so much specifically lighter: these air-bubbles, during their production, acquire a great expansive power, so as to burst the containing vessels, though ever so strong.
M. Mairan, in a dissertation on ice, attributes the increase of its bulk chiefly to a different arrangement of the parts of the water from which it is formed; the icy skin on the water being composed of filaments, which, according to him, are found to be constantly and regularly joined at an angle of ; and which, by this angular disposition, occupy a greater volume than if they were parallel. He found the augmentation of the volume of water by freezing, in different trials, a 14th, an 18th, a 19th; and when the water was previously purged of air, only a 22d part: that ice, even after its formation, continues to expand by cold; for, after water had been frozen to some thickness, the fluid part being let out by a hole in the bottom of the vessel, a continuance of the cold made the ice convex; and a piece of ice, which was at first only a 14th part specifically lighter than water, on being exposed some days to the frost, became a 12th part lighter. To this cause he attributes the bursting of ice on ponds.
Wax, resins, and animal fats, made fluid by fire, instead of expanding like watery liquors, shrink in their return to solidity: for solid pieces of the same bodies sink to the bottom of the respective fluids; a proof that these bodies are more dense in their solid than in their fluid state. The oils which congeal by cold, as oil olive, and the essential oil of aniseeds, appear also to shrink in their congealing. Hence, the different dispositions of different kinds of trees to be burnt by, or to resist, strong frosts, are by some attributed to the juices with which the tree abounds; being in the one case watery, and in the other resinous or oily.
Though it has been generally supposed that the natural crystals of ice are stars of six rays, forming angles of with each other, yet this crystallization of water, as it may properly be called, seems to be as much affected by circumstances as that of salts. Hence we find a considerable difference in the accounts of those who have undertaken to describe these crystals. M. Mairan informs us, that they are stars with six radii; and his opinion is confirmed by observing the figure of frost on glass. M. Rome de L'Isle determines the form of the solid crystal to be an equilateral octahedron. M. Hassenfratz found it to be a prismatic hexahedron; but M. d'Antic found a method of reconciling these
1er. seemingly opposite opinions. In a violent hail-storm, where the hailstones were very large, he found they had sharp wedge-like angles of more than half an inch; and in these he supposed it impossible to see two pyramidal tetrahedra joined laterally, and not to conclude that each grain was composed of octahedrons converging to a centre. Some had a cavity in the middle; and he saw the opposite extremities of two opposite pyramids, which constitute the octahedron; he likewise saw the octahedron entire united in the middle: all of them were therefore similar to the crystals formed upon a thread immersed in a saline solution. On these principles M. d'Antic constructed an artificial octahedron resembling one of the largest hailstones; and found that the angle at the summit of the pyramid was , but that of the junction of the two pyramids . It is not, however, easy to procure regular crystals in hailstones where the operation is conducted with such rapidity: in snow and hoar-frost, where the crystallization goes on more slowly, our author is of opinion that he sees the rudiments of octahedra.
Ice forms generally on the surface of the water: but this too, like the crystallization, may be varied by an alteration in the circumstances. In Germany, particularly the northern parts of that country, it has been observed that there are three kinds of ice. 1. That which forms on the surface. 2. Another kind formed in the middle of the water, resembling nuclei or small hail. 3. The ground ice which is produced at the bottom, especially where there is any fibrous substance to which it may adhere. This is full of cells like a wasp's nest, but less regular; and performs many strange effects in bringing up very heavy bodies from the bottom, by means of its inferiority in specific gravity to the water in which it is formed. The ice which forms in the middle of the water rises to the top, and there unites into large masses; but the formation both of this and the ground ice takes place only in violent and sudden colds, where the water is shallow, and the surface disturbed in such a manner that the congealing cannot take place. The ground ice is very destructive to dykes and other aquatic works. In the more temperate European climates these kinds of ice are not met with.
In many countries the warmth of the climate renders ice not only a desirable, but even a necessary article; so that it becomes an object of some consequence to fall upon a ready and cheap method of procuring it. We shall here take notice of some attempts made by Mr Cavallo to discover a method of producing a sufficient degree of cold for this purpose by the evaporation of volatile liquors. He found, however, in the course of these experiments, that ether was incomparably superior to any other fluid in the degree of cold it produced. The price of the liquor naturally induced him to fall upon a method of using it with as little waste as possible. The thermometer he made use of had the ball quite detached from the ivory piece on which the scale was engraved. The various fluids were then thrown upon the ball through the capillary aperture of a small glass vessel shaped like a funnel; and care was taken to throw them upon it so slowly, that a drop might now and then fall from the under part, excepting when those fluids were used, which
which evaporate very slowly; in which case it was sufficient barely to keep the ball moist, without any drop falling from it. During the experiment, the thermometer was kept very gently turning round its axis, that the fluid made use of might fall upon every part of its ball. He found this method preferable to that of dipping the ball of the thermometer into the fluid and taking it out again immediately, or even of anointing it constantly with a feather. The evaporation, and consequently the cold, produced by it, may be increased by blowing on the thermometer with a pair of bellows; though this was not used in the experiments now to be related, on account of the difficulty of its being performed by one person, and likewise because it occasions much uncertainty in the results.
The room in which the experiments were made was heated to of Fahrenheit; and with water it was reduced to , viz. below that of the room or of the water employed. The effect took place in about two minutes; but though the operation was continued for a longer time, it did not sink lower. With spirit of wine it sunk to . The cold was greater with highly rectified spirit than with the weaker sort; but the difference is less than would be expected by one who had never seen the experiment made. The pure spirit produces its effect much more quickly. On using various other fluids which were either compounded of water and spirituous liquors, or pure essences, he found that the cold produced by their evaporation was generally some intermediate degree between that produced by water and the spirit of wine. Oil of turpentine sunk the mercury three degrees; but olive oil and others, which evaporate very slowly, or not at all, did not sensibly affect the thermometer.
To observe how much the evaporation of spirit of wine, and consequently the cold produced by it, would be increased by electricity, he put the tube containing it into an insulating handle, and connected it with the conductor of an electrical machine, which was kept in action during the time of making the experiment; by which means one degree of cold seemed to be gained, as the mercury now sunk to instead of , at which it had stood formerly. On trying the three mineral acids, he found that they heated the thermometer instead of cooling it; which effect he attributes to the heat they themselves acquired by uniting with the moisture of the atmosphere. The vitriolic acid, which was very strong and transparent, raised the mercury to , the smoking nitrous acid to , and the marine to .
The apparatus for using the least possible quantity of ether for freezing water consists in a glass tube (fig. 1.) terminating in a capillary aperture, which is to be fixed upon the bottle containing the ether. Round the lower part of the neck at A some thread is wound, in order to let it fit the neck of the bottle. When the experiment is to be made, the stopper of the bottle containing the ether is to be removed, and the tube just mentioned put in its room. The thread round the tube ought also to be previously moistened with water or spirit before it is put into the neck of the bottle, in order the more effectually to prevent the escape of the ether betwixt the neck of the phial and tube. Hold then the bottle by its bottom FG (fig. 2.)
VOL. XI. PART I.
and keeping it inclined as in the figure, the small stream of ether issuing out of the aperture D of the tube DE, is directed upon the ball of the thermometer, or upon a tube containing water or other liquor that is required to be congealed. As ether is very volatile, and has the remarkable property of increasing the bulk of air, there is no aperture requisite to allow the air to enter the bottle while the liquid flows out. The heat of the hand is more than sufficient to force out the ether in a continued stream at the aperture D.
In this manner, throwing the stream of ether upon the ball of a thermometer in such a quantity that a drop might now and then, every ten seconds for instance, fall from the bulb of the thermometer, Mr Cavallo brought the mercury down to , or below the freezing point, when the atmosphere was somewhat hotter than temperate. When the ether is very good, i. e. capable of dissolving elastic gum, and has a small bulb, not above 20 drops of it are required to produce this effect, and about two minutes of time; but the common sort must be used in greater quantity, and for a longer time; though at last the thermometer is brought down by this very nearly as low as by the best sort.
To freeze water by the evaporation of ether, Mr Cavallo takes a thin glass tube about four inches long, and one-fifth of an inch diameter, hermetically sealed at one end, with a little water in it, so as to take up about half an inch of the cavity, as is shewn at CB in fig. 3. Into this tube a slender wire H is also introduced, the lower extremity of which is twisted into a spiral, and serves to draw up the bit of ice when formed. He then holds the glass tube by its upper part A with the fingers of the left hand, and keeps it continually and gently turning round its axis, first one way and then the other: whilst with the right hand he holds the phial containing the ether in such a manner as to direct the stream on the outside of the tube, and a little above the surface of the water contained in it. The capillary aperture D should be kept almost in contact with the surface of the tube containing the water; and by continuing the operation for two or three minutes, the water will be frozen as it were in an instant; and the opacity will ascend to C in less than half a second of time, which makes a beautiful appearance. This congelation, however, is only superficial: and in order to congeal the whole quantity of water, the operation must be continued a minute or two longer; after which the wire H will be found kept very tight by the ice. The hand must then be applied to the outside of the tube, in order to soften the surface of the ice; which would otherwise adhere very firmly to the glass; but when this is done, the wire H easily brings it out.
Sometimes our author was accustomed to put into the tube a small thermometer instead of the wire H; and thus he had an opportunity of observing a very curious phenomenon unnoticed by others, viz. that in the winter time water requires a smaller degree of cold to congeal it than in the summer. In the winter, for instance, the water in the tube AB will freeze when the thermometer stands about ; but in the summer, or even when the thermometer stands at , the quicksilver must be brought down 10, 15, or even more degrees.
degrees below the freezing point before any congelation can take place. In the summer time therefore a greater quantity of ether, and more time, will be required to congel any given quantity of water than in winter. When the temperature of the atmosphere has been about 40°, our author has been able to congel a quantity of water with an equal quantity of good ether; but in summer, two or three times the quantity are required to perform the effect. "There seems (says he) to be something in the air, which, besides heat, interferes with the freezing of water, and perhaps of all fluids; though I cannot say from my own experience whether the above-mentioned difference between the freezing in winter and summer takes place with other fluids, as milk, oils, wines," &c.
The proportion of ether requisite to congel water seems to vary with the quantity of the latter; that is, a large quantity of water seems to require a proportionably less quantity of ether to freeze it than a smaller one. "In the beginning of the spring (says Mr Cavallo), I froze a quarter of an ounce of water with about half an ounce of ether: the apparatus being larger, though similar to that described above. Now as the price of ether, sufficiently good for the purpose, is generally about 18d. or 2s. per ounce, it is plain, that with an expence under two shillings, a quarter of an ounce of ice, or ice-cream, may be made in every climate, and at any time, which may afford great satisfaction to those persons, who, living in those places where no natural ice is to be had, never saw or tasted any such delicious refreshment. When a small piece of ice, for instance, of about ten grains weight, is required, the necessary apparatus is very small, and the expence not worth mentioning. I have a small box four inches and a half long, two inches broad, and one and a half deep, containing all the apparatus necessary for this purpose; viz. a bottle capable of containing about one ounce of ether; two pointed tubes, in case one should break; a tube in which the water is to be frozen, and a wire. With the quantity of ether contained in this small and very portable apparatus, the experiment may be repeated about ten times. A person who wishes to perform such experiments in hot climates, and in places where ice is not easily procured, requires only a larger bottle of ether besides the whole apparatus described above." Electricity increases the cold produced by means of evaporating ether but very little, though the effect is perceptible. Having thrown the electrified and also the unelectrified stream of ether upon the bulb of a thermometer, the mercury was brought down two degrees lower in the former than in the latter case.
Our author observes, for the sake of those who may be inclined to repeat this experiment, that a cork confined this volatile fluid much better than a glass stopple, which it is almost impossible to grind with such exactness as to prevent entirely the evaporation of the ether. When a stopple, made very nicely out of an uniform and close piece of cork, which goes rather tight, is put upon a bottle of ether, the smell of that fluid cannot be perceived through it; but he never saw a glass stopple which could produce that effect. In this manner, ether, spirit of wine, or any other volatile fluid, may be preserved, which does not corrode cork by its fumes. When the stopple, however, is very
often taken out, it becomes loose, as it will also be by long keeping: in either of which cases it must be changed.
Bluk of the Ice, is a name given by the pilots to a bright appearance near the horizon, occasioned by the ice, and observed before the ice itself is seen.
Ice-Boats, boats so constructed as to sail upon ice, and which are very common in Holland, particularly upon the river Maese and the lake Y. See Plate CCLXXVIII. They go with incredible swiftness, sometimes so quick as to affect the breath, and are found very useful in conveying goods and passengers over lakes and great rivers in that country. Boats of different sizes are placed in a transverse form upon a 2½ or 3 inch deal board; at the extremity of each end are fixed irons, which turn up in the form of skaits; upon this plank the boat rests, and the two ends serve as out-riggers to prevent oversetting; whence ropes are fastened that lead to the head of the mast in the nature of shrouds, and others passed through a block across the bowsprit: the rudder is made somewhat like a hatchet with the head placed downward, which being pressed down, cuts the ice, and serves all the purposes of a rudder in the water, by enabling the helmsman to steer, tack, &c.
Method of making Ice-Cream. Take a sufficient quantity of cream, and, when it is to be mixed with raspberry, or currant, or pine, a quarter part as much of the juice or jam, as of the cream: after beating and straining the mixture through a cloth, put it with a little juice of lemon into the mould, which is a pewter vessel, and varying in size and shape at pleasure; cover the mould, and place it in a pail about two-thirds full of ice, into which two handfuls of salt have been thrown; turn the mould by the hand-hold with a quick motion to and fro, in the manner used for milling chocolate, for eight or ten minutes; then let it rest as long, and turn it again for the same time; and having left it to stand half an hour, it is fit to be turned out of the mould and to be sent to table. Lemon juice and sugar, and the juices of various kinds of fruits, are frozen without cream; and when cream is used, it should be well mixed.
Ice-Hills, a sort of structure or contrivance common upon the river Neva at Petersburg, and which afford a perpetual fund of amusement to the populace. They are constructed in the following manner. A scaffolding is raised upon the river about 30 feet in height, with a landing place on the top, the ascent to which is by a ladder. From this summit a sloping plane of boards, about four yards broad and 30 long, descends to the superficies of the river; it is supported by strong poles gradually decreasing in height, and its sides are defended by a parapet of planks. Upon these boards are laid square masses of ice about four inches thick, which being first smoothed with the axe and laid close to each other, are then sprinkled with water: by these means they coalesce, and, adhering to the boards, immediately form an inclined plane of pure ice. From the bottom of this plane the snow is cleared away for the length of 200 yards, and the breadth of four, upon the level bed of the river; and the sides of this course, as well as the sides and top of the scaffolding, are ornamented with firs and pines. Each person, being provided with
Ice. a sledge, mounts the ladder; and having attained the summit, he seats himself upon his sledge at the upper extremity of the inclined plane, down which he suffers it to glide with considerable rapidity, poising it as he goes down; when the velocity acquired by the descent carries it above 100 yards upon the level ice of the river. At the end of this course, there is usually a similar ice-hill, nearly parallel to the former, which begins where the other ends; so that the person immediately mounts again, and in the same manner glides down the other inclined plane of ice. This diversion he repeats as often as he pleases. The boys also are continually employed in skating down these hills: they glide chiefly upon one skait, as they are able to poise themselves better upon one leg than upon two. These ice-hills exhibit a pleasing appearance upon the river, as well from the trees with which they are ornamented, as from the moving objects which at particular times of the day are descending without intermission.
Ice-House, a repository for ice during the summer months. The aspect of ice-houses should be towards the east or south-east, for the advantage of the morning sun to expel the damp air, as that is more pernicious than warmth: for which reason trees in the vicinity of an ice-house tend to its disadvantage.
The best soil for an ice-house to be made in is chalk, as it conveys away the waste water without any artificial drain; next to that, loose stony earth or gravelly soil. Its situation should be on the side of a hill, for the advantage of entering the cell upon a level, as in the drawing, Plate CCLXXVIII.
To construct an ice-house, first choose a proper place at a convenient distance from the dwelling-house or houses it is to serve: dig a cavity (if for one family, of the dimensions specified in the design) of the figure of an inverted cone, sinking the bottom concave, to form a reservoir for the waste water till it can drain off; if the soil requires it, cut a drain to a considerable distance, or so far as will come out at the side of the hill, or into a well, to make it communicate with the springs, and in that drain form a sink or air-trap, marked I, by sinking the drain so much lower in that place as it is high, and bring a partition from the top an inch or more into the water, which will consequently be in the trap; and will keep the well air-tight. Work up a sufficient number of brick piers to receive a cart-wheel, to be laid with its convex side upwards to receive the ice; lay hurdles and straw upon the wheel, which will let the melted ice drain through, and serve as a floor. The sides and dome of the cone are to be nine inches thick—the sides to be done in screened brickwork, i. e. without mortar, and wrought at right angles to the face of the work: the filling in behind should be with gravel, loose stones, or brick-bats, that the water which drains through the sides may the more easily escape into the well. The doors of the ice-house should be made as close as possible, and bundles of straw placed always before the inner door to keep out the air.
Description of the parts referred to by the letters.—
a The line first dug out. b The brick circumference of the cell. c The diminution of the cell downwards. d The lesser diameter of the cell. e The cart wheel
or joists and hurdles. f The piers to receive the wheel or floor. g The principal receptacle for straw. h The inner passage, i the first entrance, k the outer door, passages having a separate door each. l An air trap. m The well. n The profile of the piers. o The ice filled in. p The height of the cone. q The dome worked in two half brick arches. r The arched passage. s The door-ways inserted in the walls. t The floor of the passage. u An aperture through which the ice may be put into the cell; this must be covered next the crown of the dome, and then filled in with earth. x The sloping door, against which the straw should be laid.
The ice when to be put in should be collected during the frost, broken into small pieces, and rammed down hard in strata of not more than a foot, in order to make it one complete body; the care in putting it in, and well ramming it, tends much to its preservation. In a season when ice is not to be had in sufficient quantities, snow may be substituted.
Ice may be preserved in a dry place under ground, by covering it well with chaff, straw, or reeds.
Great use is made of chaff in some places of Italy to preserve ice: the ice-house for this purpose need only be a deep hole dug in the ground on the side of a hill, from the bottom of which they can easily carry out a drain, to let out the water which is separated at any time from the ice, that it may not melt and spoil the rest. If the ground is tolerably dry, they do not line the sides with anything, but leave them naked, and only make a covering of thatch over the top of the hole: this pit they fill either with pure snow, or else with ice taken from the purest and clearest waters; because they do not use it as we do in England, to set the bottles in, but really mix it with the wine. They first cover the bottom of the hole with chaff, and then lay in the ice, not letting it anywhere touch the sides, but ramming in a large bed of chaff all the way between: they thus carry on the filling to the top, and then cover the surface with chaff; and in this manner it will keep as long as they please. When they take any of it out for use, they wrap the lump up in chaff, and it may then be carried to any distant place without waste or melting.
It appears from the investigation of Professor Beckman, in his History of Inventions, that the ancients from the earliest ages were acquainted with the method of preserving snow for the purpose of cooling liquors in summer. "This practice, (he observes), is mentioned by Solomon*†; and proofs of it are so numerous in the works of the Greeks and the Romans, that it is unnecessary for me to quote them, especially as they have been collected by others. How the repositories for keeping it were constructed, we are not expressly told; but it is probable that the snow was preserved in pits or trenches.
"When Alexander the Great besieged the city of Petra, he caused 30 trenches to be dug, and filled with snow, which was covered with oak branches; and which kept in that manner for a long time. Plutarch says, that a covering of chaff and coarse cloth is sufficient; and at present a like method is pursued in Portugal. Where the snow has been collected in a deep gulf, some grass or green sods, covered with dung from the
sleep pens, is thrown over it; and under these it is so well preserved, that the whole summer through it is sent the distance of 60 Spanish (nearly 180 English) miles to Lisbon.
"When the ancients, therefore, wished to have cooling liquors, they either drank the melted snow, or put some of it in their wine; or they placed jars filled with wine in the snow, and suffered it to cool there as long as they thought proper. That ice was also preserved for the like purpose, is probable from the testimony of various authors; but it appears not to have been used so much in warm countries as in the northern. Even at present snow is employed in Italy, Spain, and Portugal; but in Persia ice. I have never any where found an account of Grecian or Roman ice-houses. By the writers on agriculture they are not mentioned."
Ice-Island, a name given by sailors to a great quantity of ice collected into one huge solid mass, and floating about upon the seas near or within the Polar circles. — Many of these fluctuating islands are met with on the coasts of Spitzbergen, to the great danger of the shipping employed in the Greenland fishery. In the midst of those tremendous masses navigators have been arrested and frozen to death. In this manner the brave Sir Hugh Willoughby perished with all his crew in 1553; and in the year 1773, Lord Mulgrave, after every effort which the most finished seaman could make to accomplish the end of his voyage, was caught in the ice, and was near experiencing the same unhappy fate. See the account at large in Phipps's Voyage to the North Pole. As there described, the scene, divested of the horror from the eventful expectation of change, was the most beautiful and picturesque: — Two large ships becalmed in a vast basin, surrounded on all sides by islands of various forms: the weather clear; the sun gilding the circumambient ice, which was low, smooth, and even; covered with snow, excepting where the pools of water on part of the surface appeared crystalline with the young ice: the small space of sea they were confined in perfectly smooth. After fruitless attempts to force a way through the fields of ice, their limits were perpetually contracted by its closing; till at length it beset each vessel till they became immovably fixed. The smooth extent of surface was soon lost: the pressure of the pieces of ice, by the violence of the swell, caused them to pack: fragment rose upon fragment, till they were in many places higher than the main-yard. The movements of the ships were tremendous and involuntary, in conjunction with the surrounding ice, actuated by the currents. The water shoaled to 14 fathoms. The grounding of the ice or of the ships would have been equally fatal: The force of the ice might have crushed them to atoms, or have lifted them out of the water and overset them, or have left them suspended on the summits of the pieces of ice at a tremendous height, exposed to the fury of the winds, or to the risk of being dashed to pieces by the failure of their frozen dock. An attempt was made to cut a passage through the ice; after a perseverance worthy of Britons, it proved fruitless. The commander, at all times master of himself, directed the boats to be made ready to be hauled over the ice, till they arrived at navigable water (a task alone of seven days), and in them to make their voyage to England. The boats were drawn progressively three whole days. At
length a wind sprung up, the ice separated sufficiently to yield to the pressure of the full-ruled ships, which, after labouring against the resisting fields of ice, arrived on the 10th of August in the harbour of Smeeringberg, at the west end of Spitzbergen, between it and Hackluyt's Headland.
The forms assumed by the ice in this chilling climate are extremely pleasing to even the most incurious eye. The surface of that which is congealed from the sea water (for we must allow it two origins) is flat and even, hard, opaque, resembling white sugar, and incapable of being slid on, like the British ice. The greater pieces, or fields, are many leagues in length: the lesser are the meadows of the seals, on which these animals at times frolic by hundreds. The motion of the lesser pieces is as rapid as the currents: the greater, which are sometimes 200 leagues long, and 60 or 80 broad, move slow and majestically; often fix for a time, immovable by the power of the ocean, and then produce near the horizon that bright white appearance called the blink. The approximation of two great fields produces a most singular phenomenon: it forces the lesser (if the term can be applied to pieces of several acres square) out of the water, and adds them to their surface; a second and often a third succeeds; so that the whole forms an aggregate of a tremendous height. These float in the sea like so many rugged mountains, and are sometimes 500 or 600 yards thick; but the far greater part is concealed beneath the water. These are continually increased in height by the freezing of the spray of the sea, or of the melting of the snow, which falls on them. Those which remain in this frozen climate receive continual growth; others are gradually wasted by the northern winds into southern latitudes, and melt by degrees, by the heat of the sun, till they waste away, or disappear in the boundless element.
The collision of the great fields of ice, in high latitudes, is often attended with a noise that for a time takes away the sense of hearing any thing else; and the lesser with a grinding of unspeakable horror. The water which dashes against the mountainous ice freezes into an infinite variety of forms; and gives the voyager ideal towns, streets, churches, steeples, and every shape which imagination can frame.
Ice-Plant. See MESEMBRYANTHEMUM, BOTANY Index.