cisely the same salt as before. Notwithstanding all this, when I reflected, that borax is generated only in certain climates of the east, and that its acid is found only in particular substances and situations, as has been already mentioned, I could not but suppose the latter to be the produce of a new formation. This being pre'mised, I considered maturely in what manner the decomposition of this new and extraordinary compound might be attempted. Admitting the composition to be formed by the coalition of a number of different substances, it seemed not improbable that an acid, penetrating into and dissolving the whole mass, would rather associate with some than with others of its various component parts, and thus produce a separation or change of the latter. Besides, as the sedative salt, strong as its operation is, in a high degree of heat, on almost all neutral salts, has but a faint taste of acid, it might be supposed, that its acid is contained within some unknown species of earth, intimately combined; or within some sort of inflammable matter; or, according to a phrase used in the new system, there might be a deficiency of acid matter; that therefore some more powerful acid would probably separate and dissolve the earthy particles, destroy or change the inflammable matter, or impart the acid it might be supposed to want.

My choice, among the different acids, was fixed on that particular one, which, though not always quick in its operation, never fails to penetrate deep into all soluble substances, is nearly related to all inflammable bodies, and possesses an abundance of acid matter: I mean the oxygenated muriatic acid, prepared with manganese. In the application of this menstruum, I resolved to follow the practice established by the constant experience of both ancient and modern chemists; which has taught us, that difficult decompositions of parts closely united, are more easily effected by a gentle, long continued, digestive heat, and repeated distillation of the same menstruum, than by a heat which is more violent, and operates more quickly. I first made some preliminary experiments, in order to judge what probability there might be of success.

Exper. 1. I poured 14 oz. of the above-mentioned acid on 2 dr. of sedative salt, in a retort, to which I adapted a proper receiver, and then placed the mixture in a gentle digestive heat, of from 140° to 200° of Fahrenheit. The fluid was distilled over very slowly, and the salt was dry on the 3d day. The salt in the retort seemed unchanged; nor had the marine acid lost any thing of its usual smell.Exper. 2. I poured the distilled fluid out of the receiver on the same salt, and exposed them to the same degree of heat as before. The salt again became dry on the 3d day, but there was yet no appearance of any change.-Exper. 3. I repeated the same process a 3d time. I now perceived during the distillatory digestion, several bright yellow spots on the salt, as it ascended the sides of the retort, resembling well-formed ammoniacal flowers of iron; more of which I discovered after the entire exhalation of the fluid.-Exper. 4. The above change induced me to repeat the distillation; and I then perceived, not only as many, but a much

greater number of bright yellow spots, some of which were even much darker in colour, and approaching to brown. A change had now evidently taken place, which change increased on every repetition of the process; I therefore judged I might follow this direction with confidence. But, with a view to use the greatest accuracy and precaution in my proceedings and observations, I resolved to begin my work over again. First, I procured some ounces of sedative salt, which had been obtained from borax by means of vitriolic acid; and then prepared 2 quarts of the above-mentioned oxygenated muriatic acid, by distilling 3 parts of muriatic acid with 1 part of the purest manganese, in the usual manner; this I preserved in a cool dark place. Thus, the substances used in the following experiments, were always of the same nature.

Exper. 5. I poured 3 oz. of the oxygenated muriatic acid on oz. of the sedative salt, in a white glass tubulated retort. I used such a retort, that, in frequently pouring back the distilled fluid, I might not have to lute afresh the several vessels, after every distillatory digestion. For the same reason also, I chose a tubu-lated receiver, the tube of which gradually terminated in a point, in shape of a funnel. This tube passed into a phial, placed in such a manner that all the fluid passing into the receiver dropped immediately into the phial, the joinings of which were closed with bladder. To close the tube of the retort, I did not think it right to use a waxed cork, though it closes very tight, because it might be corroded; and also because the vapours, dropping from the cork, might carry some fat and oily matter back into the retort. For the same reason, I would not use any greasy lute; but closed the joints of the glass stopper, which fitted remarkably close, with a ring of fine sealing-wax, closely pressed on it, but which could easily be disengaged, after my work was done, while the retort was still warm: and as I was even afraid of an oily lute about the joints of the receiver, I closed them up with a ring of very fine white clay, which I fitted to them as exactly as possible, by pressure; letting it stand several days to dry, and then carefully filling up all the cracks. Having made this previous arrangement, and put the above-mentioned ingredients together, I suffered them to remain cold for 24 hours; at the end of which, the salt was not entirely dissolved, but, on the application of heat, the whole became a clear fluid.* The degree of heat in the sand was from 180° to 240°, by which the fluid evaporated very slowly. During this operation there ascended, or rather crept up the sides of the retort, a considerable quantity of salt, in very loose flowers, rising pretty high above the fluid, increasing by degrees, and chiefly occupying that half of the retort which received a greater degree

This appeared to me so striking, that I endeavoured to obtain a confirmation of it. I made a similar mixture, in the same proportions, which was not dissolved so long as it remained cold; but was dissolved by heat. When the solution cooled, a small part of the salt, and a larger as the cold increased, precipitated, which was dissolved again by a fresh application of heat. But with the degree of heat I employed, no more than 1 part of salt would dissolve in 6 parts of the acid.-Orig.

of heat than the other; but never the opposite or colder half. In 4 days, the fire being extinguished towards the evening of the last, the fluid had evaporated, so as to leave the salt apparently dry. After cooling for some time, the bladder on the phial was moistened by water, and the vessels were separated; the sealing-wax also having been removed, and the stopper taken out, the distilled fluid was poured back, through a glass funnel, on the salt, without disturbing the lute.

Exper. 6. As soon as the fluid was added, the salt at the bottom began by degrees to dissolve: that on the sides of the retort did the same, after it was heated, but soon began to form again: the solution appeared of a yellowish hue. In general however, the whole experiment took the same course as in exper. 5, and the smell, both of the salt and the fluid, seemed to be unchanged. The only difference was, that the former did not appear like salt, the crystallization on the sides excepted, and in single detached crystals, but something like a white, uni form, spongy, and as it were earthy mass, The fluid was now again taken from the phial, as in exper, 5, and poured back on the salt.

Exper. 7, 8, and 9. During the 3d distillation, bright yellow spots began to appear on the white flowers; and after the salt at the bottom had become dry, similar spots appeared on it, particularly on the lower surface. The fluid was again, for the 4th time, poured on the salt, and distilled; when the yellow spots: and flowers increased in number. This was also the case in the 5th distillation..

Exper. 10. The fluid obtained by the last experiment, which had changed a little in smell, and had acquired a particular scent, almost as if some sebacic acid had combined with the muriatic, was poured on the salt as before. The number of yellow spots, which had also become of a darker hue, was considerably increased. The salt had now been exposed, ever since the 5th exper. for 32 days, to the digestive distillation; and the intermediate time between each distillation had been longer or shorter, in proportion to the degree of heat, and to the time of kindling and extinguishing the fire. As I now found that business, of im portance would prevent me from continuing my labours for some months, I poured. 2 other ounces of the muriatic acid on the salt, besides the fluid so often drawn off by distillation, and left the mixture at rest.

Exper. 11, 12, 13, 14. When my business was finished, I again undertook the distilling of the mixture, which had been so long digesting in the cold, for the 7th time, and obtained the same results as in exper. 10. Nor was there much difference observed in the 12th, 13th, and 14th experiments.

Exper. 15. I now poured the fluid obtained by the 14th exper. on the salt, which had acquired more and more yellow spots, brighter in hue, and then proceeded as before, till the salt became dry; on which, when the retort was cool, I poured 1 oz. 3 dr. of the muriatic acid, in addition, and allowed the mixture to digest gently for some days. Exper. 16. In this 12th distillation, there appeared a large quantity of flocculent sublimate, looking almost like, branches, hanging

i

down, and in many places of a yellow colour; it extended even into the neck of the retort, and almost covered the interior aperture of the tube. Exper. 17. The 13th distillation produced the same phenomena. On the lowermost surface of the mass of salt, many light-brown spots appeared, as soon as the fluid was so much evaporated that no more of it could be seen on the salt.-From all these circumstances, I now believed the mass of salt, by a digestion of 22 days, and 7 distillations, from exper. 11 to 17, that is, by a digestion of 54 days, and 13 distillations, in the whole, to be so far decomposed, as to admit of a separation of some of its constituent parts. I therefore supposed I might leave off applying only digestive warmth, and proceed to a greater degree of heat.

Exper. 18. Having poured out the fluid obtained by exper. 17, and replaced the phial, I increased the degree of heat. By this the retort became quite obscured, first by fumes, and afterwards by a quantity of white sublimate, attaching itself to all its sides, which however had not the appearance of common sedative salt. As I increased the heat, the sublimate became dark in colour; afterwards became black and frothy: and at length ran down the sides of the retort, in different places, like thick oil of hartshorn, the retort being almost wholly blackened by it.—Exper. 19. While the retort was still warm, I poured into it the fluid obtained by exper. 17, having first warmed it a little; when, almost in the same instant, a very agreeable phenomenon took place. Crystals, perfectly white, shot forth suddenly, and all at once, from every part of the black mass, covering the sides of the retort. The distillation being continued, these crystals were at length dissolved, and entirely removed. The supernatant fluid was, as usual, almost colourless. When the mass of salt appeared dry, the fire was increased, as in exper. 18, and the same appearances as above related took place: first, the sublimate appeared white, then black, frothy, and flowing down the sides.-Exper. 20. I proceeded, as in exper. 19, to pour back the distilled fluid. Instantly a number of the whitest crystals shot forth from the black ground, forming small groups; but the retort was cracked.Exper. 21. I therefore took all the vessels asunder, and shook the retort well, till whatever hang on its sides was dissolved; then distilled the fluid in another retort, till the mass of salt appeared quite dry. I now put the retort into a crucible, surrounded it with sand, fitted another receiver to it, and placed the crucible in an open fire. First, some sublimate was produced, towards the neck of the retort, but which vanished as the heat increased, and then a small portion of fluid, hardly more than a dram, or a dram and a half, which appeared to smell a little of the sebacic acid. At the bottom of the retort was a blackish mass, a, and likewise some sublimate, b, which, by its varied appearance, seemed to be of a two-fold

nature.

Exper. 22. The residuum taken out of the broken retort had a spongy appearance, and swam on water; it had a blackish colour, and weighed 3 dr. 10 gr. Being exposed to the air, the blackish colour became lighter, and inclining to grey. When

digested in 16 parts of distilled water, in the usual temperature, for 24 days, it did not all sink to the bottom; and after being digested with heat for 20 hours, it was not entirely dissolved: that part which sank, was of a blackish brown. More water was then added, and it was made to boil for 2 hours; it was afterwards placed on a paper filter, the weight of which was previously ascertained, and edulcorated with boiling distilled water, till at last a proportion of 26 parts of water to the substance had been used. After all the fluid, a, had passed through, and the filter, with the residuum, had been dried in a heat of 212°, for an hour and a half, the residuum, ß, weighed, exclusive of the filter, 19 gr.—Exper. 23. The fluid, a, obtained by exper. 21, was suffered to evaporate gradually, and yielded 3 dr. 10 gr. of a white transparent salt.-Exper. 24. This salt, obtained by exper. 23, was put into a small retort, and exposed, in a crucible filled with sand, to an open fire. It became of a blackish-brown colour, yielded some sublimate, a, about 5 gr., a small portion of fluid, b, and a blackish-brown residuum, c, which became lighter in colour, on being exposed to the air.-Exper. 25. The fluid, b, of exper. 24, smelled like marine acid, and precipitated nitrate of lead.-Exper. 26. The residuum, c, of exper. 24, by the addition of some water, became whiter, and was dissolved; more water having been added, it was digested with heat, by which the matter was dissolved. The solution being afterwards filtered, I obtained 2 dr. 4 gr. of white salt: the residuum on the filter weighed 4 gr.Exper. 27. This salt, exper. 26, was again exposed to the fire; when it yielded from 20 to 30 drops of acid liquor, 4 gr. of sublimate, and a residuum which, being dissolved, yielded 1 dr. 33 gr. of salt, and left 24 gr., c, on the filter.

The same salt, obtained by Exper. 26, being distilled, became of a brownish grey colour; and, besides a few drops of fluid, yielded not quite 2 gr. of sublimate. On treating the residuum with water, it yielded 68 gr. of salt, and there were not quite 2 gr. left on the filter.

Exper. 28. On treating these 68 grs. of salt in the same manner, they yielded a few drops of fluid, and 2 gr. of sublimate: after filtration, there remained 48 gr. of salt, and a residuum of hardly 14 gr.-Exper. 29. The same salt, treated in the same manner, yielded a few drops, and a little sublimate; and after filtration, 35 gr. of salt, and a residuum of hardly 1 gr.-Exper. 30. On treating these 35 grs. of salt in the same way, they yielded, besides a very small quantity of fluid, and of sublimate, 24 gr. of salt, and about gr. of residuum.-As I now discovered that the quantity of salt was continually decreasing, and some coal separating from it, I thought it superfluous to endeavour to decompose the above 24 gr. any further.

Exper. 31. The residuum, ß, of Exper. 22, was light, blackish, and like coal. I now poured common concentrated muriatic acid on 3 grs. of it, and digested the mixture for 42 hours, in a considerable degree of heat, but no dissolution was apparent. I then added smoking nitrous acid, and digested it for 24 hours, till it