460 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799- 



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 de- 

 grees to dissolve: that on the sides of the retort did the same, after kv 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 in- 

 creased. 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 pro- 

 ceeded 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 



