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20 Dr. Pearson’s Experiments and Observations. 
II. Experiments. 
250 grains of a white, smooth, laminated, urinary calculus, 
and the same quantity of a nut-brown one, with an uneven 
surface, both of which were of a roundish figure, were pul- 
verized together.* 300 grains of these pulverized calculi were 
triturated with three ounces and a half, by measure, or five 
ounces, by weight, of lye of caustic soda. The mixture be- 
came thick, and copiously emitted ammoniacal gaz. After 
digestion for a night, and then boiling, with the addition of 
five ounces of pure water, I obtained, by filtration, five ounces 
of clear colourless liquid. 'Boiling water was repeatedly poured 
upon the strainer, till what passed through it was almost taste- 
less, and remained clear, on the addition of diluted sulphuric acid. 
(а) The matter remaining on the strainer, being dried, was 
an impalpable, white, tasteless, heavy powder, which weighed 
96 grains. 
(б) The five ounces of filtrated liquid, having been set apart, 
on standing, deposited a white, opaque, granulated, soap-like 
matter, from a colourless clear liquid. The liquid being de- 
canted, the deposit was dried, and was then an opaque, brittle, 
soap-like matter, which dissolved readily in water, giving a 
clear but not viscid solution, and tasting weakly of soda. This 
soap-like matter weighed 280 grains. 
(c) The decanted liquor, (6,) being mixed with the above 
filtrated liquors, on evaporation to three ounces, afforded no 
deposit on standing, although it was a very heavy and soapy 
• The object of these experiments being principally to investigate the properties of 
one of the constituent parts of urinary concretions, which part was previously deter- 
mined (by the test of nitric acid,) to exist in both these, it can be no objection to the 
experiments, that I made use of a mixture of two calculi. 
