200 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 



perature, from the fire applied, was at first very low, but was gradually increased, 

 so as to make the coated part, containing the charge, red-hot. 1st, the precipi- 

 tate turned black, and a little water appeared. 2d, gaz came over, which had the 

 smell of empyreumatic liquor cornu cervi. 3d, a brown sublimate appeared, and 

 gaz as before, but also with prussic acid gaz. 4th, black matter, staining the 

 tube, as if from tar, or animal oil. On cooling, there was found a residue, of 

 nearly 3 gr., of pure carbon. The sublimate was principally carbonate of ammo- 

 nia; the rest was animal oil. The gaz discharged was nearly 4. its bulk, or 5 cubic 

 inches by measure, carbonic acid; and the remaining 5 cubic inches were nitrogen 

 gaz, containing prussic acid and empyreumatic oil. 



I treated in the same manner, the same quantity of reddish crystals, deposited 

 spontaneously from urine. The result was not very different from that of the 

 former experiment. The gaz was more offensive, smelling like putrid urine, and 

 the carbonaceous residue was more copious, and contained lime and phosphoric 

 acid; at least the lixivium of it became white, on dropping into it oxalic acid; and 

 it became slightly curdy, on adding lime water. I treated, in the same manner, 

 some quite round and smooth concretions, of the size of black pepper seeds. The 

 products were the same as the former, but the gaz was still more offensive, and in 

 smaller quantity; and the carbonaceous matter was more copious. In the same 

 way I subjected to experiment 20 gr. of a nut-brown light calculus, which I had 

 previously ascertained to contain the matter above described, which was precipitated 

 from caustic soda by acids. The products were of the same kind as the former; 

 but I could find no trace of phosphoric acid in the residue, which I did of lime, 

 and the gaz was less offensive. The carbonaceous residue was not in weight, 3 gr. 



It will be proper, before I proceed further, to point out some of the more ob- 

 vious conclusions from the above experiments. 1 . It appears that at least -i- of the 

 matter of the urinary concretions subjected to the above experiments united to 

 caustic soda, and was precipitated from it by acids. (2, a — d.) 2. This precipi- 

 tate does not indicate acidity to the most delicate tests; (e, 2), and, as it is inodo- 

 rous, tasteless, (<?, l), scarcely soluble in cold water, (e, 2), does not unite to 

 the alkali of carbonate of pot-ash, of soda, or of ammonia, (e, 3, 4), nor to 

 oxide of mercury, (e, 4), nor to the lime of lime water, (<?, 8), nor decompound 

 soap, (e, 10), or prussiate of iron, (e, 13), and, as its combination with caustic 

 soda, resembles soap, more than any double salt known to consist of an acid and 

 alkali, this precipitate does not belong to the genus acids. 3. As this precipitate 

 could not be sublimed, without being decompounded, like animal matter, (e, 15), 

 and also for the reasons mentioned in the last paragraph, it cannot be the same 

 thing as the acid sublimate of Scheele, or the succinic acid. 4. As it does not 

 appear to be putrescible, nor form a viscid solution with water, it cannot be referred 

 to the animal mucilages. 5. On account of its manner of burning in the air, 

 under the blow-pipe, (e, 6), and its yielding, on exposure to fire in close vessels, 

 the distinguishing pucts of animal matter, especially ammonia and prussic acid* 



