400 A Memoir on the Uric Acid. 
teristic property (of affording a red colour 
with nitric acid) to the admixture of urea, 
and denies it to the pure uric acid. I have 
satisfied myself, however, that it belongs even 
most remarkably to the purified acid, and that 
it cannot by any process be obtained from 
urea. 
6. The watery solution of uric acid does 
not produce any change in the solutions of 
earths or metals in acids. 
7. The dry acid is not at all acted upon by 
the solutions of the alkaline carbonates, or 
sub-carbonates. Even digestion with them, 
for several hours, occasions no greater loss of 
weight, than would be produced by a quan- 
tity of water equal to that of the solution. 
This fact I determined by repeated expe- 
riments, both on account of its influence on 
medical practice ; and because, though test» 
fied by every preceding writer, it has lately 
been denied by Dr. Egan.(q) It suggests 
the necessity of administering alkalis in a 
pure state, whenever they are given with the 
view of dissolving a stone, which is already 
formed in any of the urinary passages. 
8. The watery solution of uric acid does 
not decompose soap ; but when the dry acid 
(q) Irish Transactions x. 289. 
