on the Composition of Urinary Concretions. 27 
concretions, of the size of black pepper seeds. The products 
were the same as the former, but the gaz was still more offen- 
sive, and in smaller quantity; and the carbonaceous matter 
was more copious. 
I, in the same way, subjected to experiment 20 grains 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 offen- 
sive. The carbonaceous residue was not, in weight, 3 grains. 
It will be proper, before I proceed further, to point out 
some of the more obvious conclusions from the above experi- 
ments. 
1. It appears that at least one half of the matter of the 
urinary concretions subjected to the above experiments united 
to caustic soda, and was precipitated from it by acids. ( II. 
a—d .) 
2. This precipitate does not indicate acidity to the most de- 
licate tests; ( e , 2.) and, as it is inodorous, tasteless, (e, 1.) 
scarcely soluble in cold water, (e, 2.) does not unite to the 
alkali of carbonate of potash, of soda, or of ammoniac, (^,3, 
4.) nor to oxide of mercury, (*?, 4.) nor to the lime of lime wa- 
ter, ( e , 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 
■ E 2 
•OAS 
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