Dr. Pearfon’s Experiments on Calculi. 267 
III. Weak nitric acid attacks it cold: with the affiftance 
of heat there is produced an effervefcence and red vapour3:. 
the calculus is entirely diffolved, and carbonic acid is dif- 
engaged. This folution is acid, even when faturated: with 
the calculus: it gives a beautiful red colour to the fkin in 
half an hour; when evaporated it becomes of a blood red; _ 
a drop of acid then added deftroys the colour; it does not’ 
precipitate the muriat of barytes nor metallic folutions, even r 
with the addition of an alkali; the latter makes it turn 
yellow; a fuperabundance of alkali gives it, by digeftion, a 
rofe colour, as well as the’ property of precipitating fulphat 
of iron black, fulphat of copper green, nitrat of filver grey, 
the fuperoxygenated nitrat of mercury and folutions of 
zine and lead white. The fame nitric folution of the calcu- 
lus of the bladder gives, with lime water, a white precipitate, 
which diffolves without effervefcence in the nitric and muri- 
atic acids without deftroying their acidity. The oxalic acid 
added to the nitric folution gives no precipitation. 
IV. Potafh united to the carbonic acid does not diffolve 
the urinary calculus, either hot or cold; but a perfeétly’ 
cauftic ley of the fame alkali, without any trace of the 
earbonic acid, diffolves it even cold. This folution is yellow, 
of a fweetith tafte; it is precipitated by all the acids, even 
the carbonic; it does not render lime water turbid; it de- 
_ compofes and precipitates metallic folutions, thofe of iron 
brown, of copper grey, of filver black, of zinc, mercury and 
Jead white: it exhales an odour of ammonia. 
V. Lime water diffolves the calculus by digeftion; 200: 
parts almoft are neceflary to take up one; it then lofes its 
fharp tafte; this folution is precipitated in part by acids. 
VI. Pure water diffolves entirely the ftone of the human 
bladder ; but it is neceffary to boil, for fome time, 360 parts 
with one part of the calculus reduced to powder to effect a 
folution. This folution, beimg then complete, reddens a 
tincture of turnfole; does not render lime water turbid; 
and 
