a new species of Urinary Calculus. 225 
it yields foetid carbonate of ammonia, partly fluid, and partly 
in a solid state, and a heavy foetid oil, such as usually pro- 
ceeds from animal substances ; and there remains a black 
spongy coal, much smaller in proportion than is found after 
the distillation of uric calculi. 
Under the blow-pipe it may be distinguished from uric 
acid by the smell, which at no period resembles that of prus- 
sic acid ; but in addition to the usual smell of burned animal 
substances, there is a peculiar foetor, of which I cannot give a 
correct idea, as I know no smell which it can be said to 
resemble. 
This species of calculus is so readily acted upon by the 
generality of common chemical agents, that its character may 
perhaps be most distinctly marked, by an enumeration of 
those feeble powers that it can resist. 
It is not dissolved (excepting in very small proportion) by 
water, by alcohol, by acetic acid, by tartaric acid, by citric 
acid, or by saturated carbonate of ammonia. 
The solvents on the contrary, are far more numerous. It 
is dissolved, in considerable quantity, by muriatic acid, by 
nitric acid, by sulphuric acid, by phosphoric acid, and by 
oxalic acid. 
It is also dissolved readily by pure alkaline menstrua : by 
potash, by soda, by ammonia, and by lime water. It is even 
dissolved by fully saturated carbonates of potash or of soda. 
Accordingly, these alkalies are not so convenient for the pre- 
cipitation of this matter from acid solutions, as the carbonate 
of ammonia, which is not capable of redissolving the precipi- 
tate, though added in excess. 
For a similar reason, the acids best suited for its precipita- 
