390 Fourcroy’s Examination of Dr. Pearfon. 
~ All that Dr. Pearfon has done gives niore ftrength fiill'to 
the well founded opinion which has caufed this body to be 
claffed among the acids. It differs particularly from the ox-' 
yds by its unalterability, its imputrefcibility, its folubility in 
alkalies, its refiftance to acidification; and it would be de- 
ranging tono purpofe the refults and opinions of modern 
chemiftry to place it in that clafs of compounds with which 
it in reality has no relation. I thall then continue with all 
the French chemifts to confider human urinary calculi’ as 
containing, moft frequently, and, fometimes, altogether, a 
Weak acid, the characters of which were well determined 
before Dr. Pearfon, and even confirmed by his refearches. 
I fhall add one important obfervation, that of all the acids 
it is that which cryftallifes the fooneft, and whofe moleculz 
perhaps are moft altered; which affumes with the greateft 
eafe the concrete and {parry form, under which, as it is feen 
in regular ealculi and in compact firata, it almoft’ eludes ‘the 
aétion of the moft powerful re-agents and folvents; and 
itis to this laft property, the moft terrible and affliGting for 
humanity, that what is called the {tone im the bladder mutt 
without doubt refit the ation of all the known folvents, 
and has hitherto given no hop nes of the difcoy ery of'a lithon- 
triptic. 
-'-Tn ‘the prefent ftate of etait the particular matter of 
human urinary calculi appears only as a com bination, w here 
abundance of carbon and azot united to a fall quantity of 
hydrogen are ‘inclined to’ a flight acidification by’ the fixed 
“Oxyg cen which they contain.’ The proportion even’ of thefe 
pritnitive materials has not yet been determined, After hav- 
ing examir ned 'the labours of Dr. Pearfon, T muft agree with 
him, that the name /i/hic acid given to this animal conere- 
tion, and which has been borrowed from the medical term 
li hiafis, de ferves that reproach of im propriety w ‘hich he be- 
ffows on it. Tam of ( opinion thatwe ‘hight adopt with ad- 
vantage that of buric acid, fince! this Buay Has not yet “been 
found but in the tirine of man; and'that ven if fattire expe- 
t 
4 riments 
