26o On the Decompofitlon of the Acid of Borax. 



my work was done, while the retort was ftill warm: and as I was even afraid of an oily lute 

 about the joints of the receiver, I clofed them up with a ring of very fine white clay, which 

 1 fitted to them as exa£lly as poflible by preffure, letting it ftand feveral days to dry, and 

 then carefully filling up all the cracks. Having made this previous arrangement, and put the 

 abovementioned ingredients together, I fufFered them to remain cold for twenty-four hours ; 

 at the end of which the fait was not entirely diflblved, but upon the application of heat the 

 whole became a clear fluid *. The degree of heat in the fand was from i8o to 240, by 

 which the fluid evaporated'very flowly. During this operation there afcended, or rather 

 crept up the fides of the retort, a confiderable quantity of fait in very loofe flowers, rifmg 

 pretty high above the fluid, increafing by degrees, and chiefly occupying that half of the 

 retort which received a greater degree of heat than the other, but never the oppofite or colder 

 half. In four days, the fire being extinguiflied, towards the evening of the lad the fluid had 

 evaporated fo as to leave the fait apparently dry. After cooling for fome time the bladder 

 upon the phial was moiftened by water, and the veflels were feparated ; the fealing-wax alfo 

 having been removed, and the ftopper taken out, the diftilled fluid was poured tack through 

 aglafs funnel upon the fait, without difturbing the lute. 



Exper, VI. As foon as the fluid was added, the fait at the bottom began by degrees to 

 diflblve ; that on the fides of the retort did the fame after it was heated, but foon began to 

 form again : the folution appeared of a yellowifh hue. In general, however, the whole 

 experiment took the fame courfe as in exper. V. and the fmell both of the fait and the fluid 

 feemed to be unchanged. The only difFerence was, that the former did not appear like fait 

 the cryflallization on the fides excepted, and in fmgle detached cryflals, but fomething like 

 a white uniform fpongy, and, as it were, earthy .mafs. The fluid was now again taken from 

 the phial, as in exper. V. and poured back upon the fait. 



Exper. VII. VIII. and IX. During the third difi:il!ation, bright yellow fpots began to 

 appear upon the white flowers ; and after the fait at the bottom had become dry, fimilar fpots 

 appeared upon it, particularly upon the lower furface. The fluid was again for the fourth 

 time poured upon the fait, and diftilled, when the yellow fpots and flowers increafed in 

 number. This was alfo the cafe in the fifth diftillation. 



Exper. X. The fluid obtained by the lafl: experiment, which had changed a little in fmell 

 and had acquired a particular fcent, almoft as if fome febacic acid had combined with the mu- 

 riatic, was poured upon the fait as before. The number of yellow fpots, which had alfo be- 

 come of a darker hue, was confiderably increafed. The fait had now been expofed ever 

 fince the fifth exper. for thirty-two days, to the digeftive diftillation, and the intermediate 

 time between each diftillation had been longer or fliorter in proportion to the degree; of heat 



• This appeared to mc fo ftriking, that I endeavoured to obtain a confirmation of it. I made a fimilar 

 mixture in the fame proportions, which was not diflblved fo long es it remained cold, but was diflblved by 

 heat. When the folution cooled, a fmall pan of the fait (and a larger as the cold increafed) precipitated, 

 which was diflblved again by a frefli application of heat. But with the degree of heat I employed, no more 

 than one part of fait would diflblve in fix parts of acid. 



and 



