Dr. Pearfon’s Experiments on Calculi. 387. 
lation of this matter which I obtained from a quantity. at 
leaft fix times as large as that which he employed. 
In what regards the acid and cryftalline fublimate obtained _ 
in the diftillation, except. the.apparatus of a bent tube def- 
tined to feparate the produéts, I can fee nothing new ; only 
here the author gaye himfelf needlefs.trouble to fearch, for 
our lithic acid in this manner,.fince, as, I have already faid; 
it was not this produét. of the fublimation and decompofition 
by fire that I diftinguifhed by the name of the lithic acid in 
our nomenclature. 
The attempts made. by Dr. Pearfon to. acidity his fuppofed 
oxyd by the nitric acid and the oxygenated muriatic acid 
could not poffibly fucceed : like thofe whe preceded him, he 
found that the calculus was changed into carbonic acid and 
ammonia. 
Refpeéting the portions of the calculi not foluble.in alkali, 
and which, Dr. Pearfon afferts, exhibited to him all the pre- 
perties of phofphat of lime, I, {hall obferve, that if by this 
fact he feems to deviate more from. thofe who vent before 
him, it was only from, two-calculi, mixed in equal parts, that 
he, obtained fuch a refult, and) that the very. variable dif 
ference of the.proportion of the fubiances. foluble and 
infoluble, in the 300,,urinary coneretions, which he fays 
he examined comparatively, can, furnif no oppofition to 
the. relult of Scheele in regard to the matter called /ithic 
acid. ; 
As to the produét of the numerous oat a fetel which 
Dr. Pearfon. tried on more than 300 human urinary calculi, 
which he compared with each other, I find no other differ- 
eace between what he announces and what, was announced 
by his predeceffors, but the variety, of the nature which, thefe 
experiments fhewed to him between thefe, concretions—a.va- 
riety which, however, always fliews,.the greateft_ proportion 
in the kind of matter called by, him the ouric oxyd.,, It is in 
this/refult that Dr. Pearfon deviates moft from Scheele, who 
afierted that all the calculi of the human bladder refembled 
Cc2 each 
