398 A Memoir on the Uric Acid. 
is various, from pale straw yellow to deep 
brown, sometimes with an intermixture of 
red; and the divided surfaces bear consider- 
able resemblance to wood. ‘To separate the 
uric acid from the other substances with 
which it is mixed, the calculus, finely pow- 
dered, is to be dissolved in a heated solution 
of pure potash. The solution is to be poured 
into a quantity of diluted muriatic acid, which ~ 
is more than sufficient to saturate the alcali; 
and the precipitate is to be repeatedly washed 
with a large quantity of distilled water. In 
order to remove any adhering portion of mu- 
riatic acid, a little carbonate of ammonia, 
may also be added to the first washings. 
After edulcoration, it may be dried in a tem- 
perature not exceeding 212° Faht. 
1. In this state, the uric acid has the form 
of white shining plates, somewhat resembling 
those of the acid of borax, but considerably 
smaller. It is perfectly soft to the touch, and 
entirely destitute of taste and smell. 
2. When added in powder to the infusion 
of litmus, it changes the blue colour of that 
liquid to red, but less distinctly than the mi- 
neral and most of the vegetable acids. 
3. Four ounce measures of boiling distilled 
water take. up about 1.4 grain, and. of this 
about half a grain separates again on cooling. 
