3 "3 3 
on the Composition of Urinary Concretions. 2 1 
liquid to the feel ; but, on adding diluted sulphuric acid gra- 
dually, till it ceased to become turbid, a sediment was deposited, 
which was a very light, white, impalpable powder, in weight, 
when dried, 26 grains. The liquid from which this powder 
was precipitated, being evaporated, afforded nothing but sul- 
phate of soda, and a few grains of crystals, which seemed to be 
phosphate of soda. There was also a blackish matter, which 
burnt like horn, or other animal matter, and did not leave a 
pink or rose-coloured matter, on evaporating the solution of it 
in nitric acid to dryness, but left a carbonaceous residue; 
whereas, the white precipitate, so treated, afforded a beautiful 
pink matter. 
( d ) 250 grains of the soap-like matter (b) being dissolved 
in eight ounces of pure water ; 
1. A little of this solution, further diluted by one ounce of 
water, grew milky on adding a few drops of nitric acid, but 
became less so on standing. On adding more nitric acid, and 
heating it, the mixture became quite clear : by adding a few 
drops of lye of caustic soda, a very slight curdy appearance 
took place. 
2. On adding, to the same diluted solution, a little of the 
diluted sulphuric or muriatic acid, milkiness ensued, and re- 
mained, although the acids were added till the mixture was 
extremely sour. On adding lye of caustic soda, much more 
than to saturate the superabundant acid, the mixture became 
clear again; and, on adding the acids a second time, the milki- 
ness was reproduced. It was found that the milkiness could 
be produced and destroyed, or clearness be produced, by the 
alternate addition of the acid and alkali, for an unlimited num- 
ber of times. If the nitric acid however was used, at length 
