in chemistry, a salt in appearance somewhat similar to crystals of alum, brought originally from the East Indies in an impure state, and afterwards freed from its impurities by certain processes in the European countries. It was long a matter of uncertainty whether this salt be a natural or fictitious substance in those countries from whence it is brought; but it is now beyond a doubt, that it is naturally produced in the mountains of Thibet, from whence other parts of the eastern continent are supplied. Mr Kirwan, in his mineralogy, informs us, that Mr Grill Adamson sent some to Sweden in the year 1772, in a crystalline form, as dug out of the earth in the kingdom of Thibet, where it is called powxna, my powx, and hou powx. It is said to have been found in Saxony in some coal-pits.

In the Philosophical Transactions, vol. 77, we have two different accounts of the place where it is found, and the manner of obtaining it. One of these is by William Blane, Esq; who tells us that in the language of the country it is called fuwazab, and is brought into Hindoostan from the mountains of Thibet. It is produced in the kingdom of Jumlate, about 30 days' journey north from Betowle, a small principality about 200 miles N. E. of Lucknow. The place where it is found is said to be a small valley surrounded with snowy mountains, in which is a lake about six miles in circumference; the water of which is constantly so hot that the hand cannot bear it for any time. Around this lake the ground is perfectly barren, not producing even a blade of grass; and the earth is so full of a saline matter, that after falls of rain or snow it concretes in white flakes on the surface like the natron of Hindoostan. On the banks of this lake, in the winter season, when the falls of snow begin, the earth is formed into small reservoirs five inches high: when these are filled with snow, the hot water from the lake is thrown upon it; which, together with the water from the melted snow, remains in the reservoir, to be partly absorbed by the earth and partly evaporated by the sun; after which there remains at the bottom a case of sometimes half an inch thick of crude borax, which is taken up and reserved for use. It can only be made in the winter season, because the falls of snow are indispensably requisite, and also because the saline appearances upon the earth are strongest at that time. When once it has been made on any spot, it cannot be made again on the same until the snow has fallen and dissolved three or four times, when the saline efflorescence appears as before. The borax, in the state in which it is taken off the earth, is carried from hill to hill upon goats, and passes through many hands, which increases the difficulty of obtaining any authentic information concerning the original manufacture. When brought down from the hills, it is refined from the gross impurities by boiling and crystallization. Our author could obtain no answer from those who gave him the account, to any of his questions concerning the quality of the water. ter and the mineral productions of the soil. All they could tell him was, that the water was very hot, very foul, and as it were greasy; that it boils up in many places, and has a very offensive smell; and that the soil is remarkable only for the saline appearances already mentioned. The country in general produces considerable quantities of iron, copper, and sulphur; and our author was assured that all the borax in India came from this place.

As this part of Asia is entirely unfrequented by Europeans, our author could only obtain his information from the natives; however, as he had an opportunity of seeing some of those who resided near the spot, it might be reckoned as genuine as could well be expected. The place, he tells us, is inaccessible not only to the Europeans, but even to the inhabitants of Indostan, being never visited by any of them except a few wandering Faquirs, who have been sometimes led there, either with a view to visit some of the temples in the mountains, or to do penance. They describe the cold in winter to be so intense, that every thing is frozen up; and life can only be preserved by loads of blankets and skins. In the summer, again, the reflection of heat from the sides of the mountains, which are steep and close to one another, renders the heat intolerable. With respect to the credibility of the account, he observes, first, "That borax is really brought from the mountains of Thibet is certain, as he himself often had occasion to see large quantities of it brought down, and had purchased it from the Tartar mountaineers, who brought it to market; secondly, he had never heard of its being produced or brought into India from any other quarter; and, thirdly, if it was made on the coast of Coromandel, as some books mention, he thinks there can be little doubt but that the whole process would have been fully inquired into, and given to the public long before this time."

The other account is from father Joseph de Ravato, president of the mission of Thibet, and sent in a letter to the Royal Society, communicated by Joseph Banks, Esq.; He pretends also to have had his intelligence from a native of the country where the borax is made, though it differs very considerably from that of Mr Blare. "In the province or territory of Marme (says he), 28 days journey to the north of Nepal, and 25 to the west of Lassa, the capital of Thibet, there is a vale about eight miles broad. In a part of this vale there are two villages or castles, the inhabitants of which are wholly employed in digging the borax which they sell into Thibet and Nepal, they having no other means of subsistence, the soil being too barren as to produce nothing but a few rushes. Near these two castles there is a pool of moderate size, and some smaller ones, where the ground is hollow and the rain-water collects. In these pools, after the water has been some time detained in them, the borax is formed naturally: the men wading into the water, feel a kind of a pavement under their feet, which is a sure indication that borax is there formed; and there they accordingly dig it. Where there is little water, the layer of borax is thin; where it is deep, it is thicker; and near the latter there is always an inch or two of soft mud, which is probably a deposit of the water after it has been agitated by rain or wind. Thus is the borax produced merely by nature, without either boiling or distillation.

The water in which it is formed is so bad, that the drinking a small quantity of it will occasion a swelling of the abdomen, and in a short time death itself. The earth that yields the borax is of a whitish colour; and in the same valley, about four miles from the pools, there are mines of salt, which is there dug in great abundance for the use of all the inhabitants of these mountains, who live at a great distance from the sea. The natives, who have no other subsistence on account of the sterility of the soil, pay nothing for digging borax; but strangers must pay a certain retribution, and usually agree at so much per workman. Ten days' journey farther north, there is another valley named Tapre, where they dig borax; and another still farther to the northward, named Giiga. Borax, in the Hindoo and Nepalese languages, is called Soaga. If it be not purified, it will easily deliquesce; and in order to preserve it for any time till they have an opportunity of selling it, the people often mix it with earth and butter. In the territory of Mungdan, 16 days' journey to the north of Nepal, there are rich mines of arsenic; and in various other places are found mines of sulphur, as also of gold and silver, whose produce is much purer than those of the mines of Pegu."

Mr Fourcroy informs us, that borax is found in commerce in three different states. 1. Crude borax, tincal, or chrysocholla, which comes from Persia. He describes it as consisting of a greenish mass of a greasy feel, or in opaque crystals of an olive green, which are fixed prisms terminated by irregular prisms. There are two varieties of these crystals, differing in magnitude: this salt is very impure by the addition of foreign matters. Mr Kirwan tells us, that this kind is called brute borax, tincal, or chrysocholla, and that it is in the form of large, flat, hexangular, or irregular crystals, of a dull white or greenish colour, greasy to the touch; or in small crystals, as it were cemented together by a rancid, yellowish, oily substance, intermixed with marl, gravel, and other impurities. Mr Engelstrom, he adds, has a suspicion that the tincal is only the residuum of the mother liquor of borax evaporated to dryness; and that the greasiness arises from its being mixed with butter-milk, to prevent its efflorescence.

2. Borax of China is somewhat purer than the foregoing, and is met with in the form of small plates or masses irregularly crystallized, and of a dirty white. It appears to consist of fragments of prisms and pyramids confounded together without any symmetrical arrangement: a white powder is observed on the surface, which is thought to be of an argillaceous nature.

3. The Dutch or purified borax, in the form of portions of transparent crystals of considerable purity. Pyramids with several facets may be observed among them, the crystallization appearing to have been interrupted. "This form (says Mr Fourcroy) shows to a certainty that the Dutch refine this salt by solution and crystallization."—Mr Kirwan says, that it is purified by solution, filtration, and crystallization; and the crystals thus obtained are calcined, to free them still farther from greasiness; and then dissolved, filtered, and crystallized, a second time. Sometimes more mineral alkali is added, as tincal is said to contain an excess of sedative salt. Mr Fourcroy tells us, that a purified borax, not inferior to the Dutch, but perhaps even even of greater purity, is prepared by some chemists at Paris.

The same author informs us, that Mr La Piame, an apothecary at Paris, has discovered, that it is continually formed in the soap-fuds and refuse-waters of the kitchen, which a person preserves in a kind of ditch; and from which, at the end of a certain time, he obtains true borax in fine crystals. "All that we can deduce (says he) from the known facts concerning its formation, is simply, that it is produced in stagnant waters which contain fat matters." Some authors affirm, that it is produced by art in China. A mixture of grease, clay, and dung, is said to be deposited in a ditch, *fritum superfluation*. This mixture is sprinkled with water, and fulleried to remain for some years; at the end of which time it is lixiviated, and affords crude borax by evaporation. Others have supposed that it is obtained from water, which filters through copper mines. Mr Beaume positively affirms, that the former of these processes succeeded very well with him; but Dr Black gives little credit to his assertions.

Borax serves as a flux to vitrifiable earths, with which it forms a good glass, and is employed in making artificial gems. It vitrifies clay, but much less completely than siliceous earths; and from this property it adheres to the inside of crucibles, and glazes them.

Borax, as is related at length under the article Chemistry, is a peculiar neutral salt formed by the union of a kind of acid with mineral alkali. This acid, from some supposed properties of allaying the heat of fevers, has the name of *fat sedative*, which it still retains. It has been supposed to be an artificial product, and perhaps may be artificially made*: but Mr Hoefer, apothecary to the grand duke of Tuscany, has discovered that the waters of several lakes of that country contain it in a state of great purity; and the chemists of the academy of Dijon have confirmed this discovery by analysing the waters of Monte Rotondo, which were sent to them; and in which they found sedative salt, as discovered by Mr Hoefer. It is probable (says our author) that it may hereafter be found in other mineral waters; and it seems to be produced by the putrefaction of fat substances.

Mr Hoefer first discovered this acid in the waters of the Lagoon named Cerchio near Monte Rotondo, of which discovery an account was published in the year 1778. The same was found, in a concrete state, by Mr Paul Masgagni professor of Anatomy, in several streams of the Lagoon in the neighbourhood of Siena and Volterra. He enumerates five places; viz. the Lake of Travo, 20 miles to the west of Sienna; that of Rotondo, which lies 30 miles to the westward of the same town; of del Salto, three miles further; at another called Sarazzano, six miles from Monte Rotondo; another named Castel Nuovo, seven miles from Monte Rotondo and 24 from Sienna; and that of Monte Cerboli, four miles distant from Castel Nuovo. In the neighbourhood of all these lakes are considerable springs of hot water rushing out of the earth, some clear, and some muddy; either of a dark or a whitish colour; and, in some, a kind of metallic crust or pellicle is perceived on the surface of the water. Many cavities from which the waters rush out seem to be true small volcanic craters, and continually emit from the earth vapours of a sulphureous and ammoniacal nature. These waters not only contain the acid of borax, both in the fluid and concrete state, but various other concretions are there observed, such as martial vitriol, ammoniacal, aluminous, concrete boracic salts, brimstone, &c.

"It is remarkable (says our author, p. 363.), that, near 40 years ago, Dr Hill, in his notes to *Theophrastus's Treatise on Stones*, affirmed, that borax was a salt made by evaporation of an ill tincted and foul water, of which there were springs in Persia, Mulcovy, and Tartary. But he was hardly believed, on account of the many bold and groundless assertions of which he had been found guilty in almost all his numerous works. Mr Beaume at Paris pretended to have discovered the method of making the sedative salt by a long maceration of greasy and earthy substances; but nobody has yet been able to verify this fanciful discovery.

"The unrefined borax which is brought to Europe under the name of *tincal*, looks like soft soap, is fat, and covers or encrusts the borax crystals. The mine-master, Mr Swab, has published some experiments upon this tincal in the acts of the Royal Academy of Sciences at Stockholm for 1756. He found in it a martial earth, and a fat substance, which, to smell and other circumstances, comes nearest to a mineral fat: as also, that pure borax does not yield any *hepar sulphuris* when united with a phlogiston and a vitriolic acid; from which he concludes, that borax is prepared from its own particular mineral substance.

"Professor Pott and M. d'Hennouville have very carefully examined the refined borax; and from their experiments, which have been published, it is evident, that it is of a peculiar nature. However, there remains to be known, for certain, from whence it is prepared by the Indians: for if it is produced from a mineral substance, as is very probable, there must exist other mixtures and compositions as yet unknown to the learned world.

"I have also found in the tincal small bits of leather, bones, and small pebbles, whence there is no certainty to be concluded on from its examination; but if it should happen that it is prepared from animal substances, it must be allowed, that nature has formed an alkaline salt in the animal kingdom analogous to the *fat fusibile microcosmicum*. Some years ago a report was propagated from Saxony, that somebody had discovered there a substance out of which borax could be made, and also the art of preparing it: but nothing more has transpired since, than that the author showed it in secret to his friends, and gave a description of it which was only intended to mislead them, if he really did profess the art."

According to Mr Kirwan, 100 parts of purified borax contain 32 of real boracic acid, 17 of mineral alkali, and about 47 of water; but of this quantity of mineral alkali only about five parts are saturated; whence, in many cases, borax acts as an alkali. Bergman informs us, that it requires an equal weight of acid to make the alkaline properties entirely disappear; and Dr Withering, that double the quantity of acid is required for this purpose, both in the tincal and refined borax.

This acid, like the borax in substance, is made use of to fuse vitrifiable earths, with which it forms clear and nearly colourless glasses; by the influence of heat it dissolves