148 ESSAY IX. 



lime-water. The lime-water thereby loses its caustic taste. 

 On adding acids to this solution, the calculus is partly 

 precipitated. 



SECTION VI. 



Pure water dissolves the calculus entirely, but a large 

 quantity is requisite for this purpose. If 8 grs. of finely 

 powdered calculus be boiled for a short time with 5 oz. 

 of water, they will be dissolved. The tincture of lacmus 

 is turned red by this solution. Lime-water is not pre- 

 cipitated. As it grows cold, the greatest part of the calculus 

 separates again in the form of fine crystals. 



SECTION VII. 



On distilling, in a small glass retort, 1 drm. of calculus 

 in the open fire, I obtained a volatile alkaline liquor, like 

 that from hartshorn, but no oil. In the neck of the 

 retort there was a brown sublimate. Upon heating the 

 retort thoroughly red hot, and then leaving it to cool, I 

 obtained a black coal, weighing 12 grs., which, when put 

 upon red-hot iron in the open air, retained its black 

 colour. The sublimate, which seemed to have been some- 

 what fused, weighed 28 grs., and on being purified by a 

 new sublimation, it grew white. It had no smell, but a 

 somewhat sourish taste, and was easily soluble in boiling 

 water. It also dissolved in spirit of wine, but a larger 

 quantity than of water was requisite for this purpose. 

 Lime-water was not precipitated. The sublimate seemed 

 to agree in some respects with the sal succini. 



From these experiments I conclude that, since the 

 terra ponderosa (Sec. in. (d)) is not precipitated, which 



