382 Fourcray’s Exattination of 
thofe given by Scheele. Having indeed reprefented it, after 
this illuftrious chemift, as afolid acid cryftallifed in lamine, 
infipid, giving a faint red tinge to blue. colours, foluble in 
eauflic alkalies and in the nitric acid, affuming with the 
Jatter a beautiful red colour, decompofable by fire, yielding 
a great deal of the carbonic acid and little oil; the weakeft 
of all: the acids; containing lime and alkaline -phofphats 
nly by accident. -I.add to thefe charaéters the following 
properties eftablifhed by the analyfis of a great number of 
varieties of thefe concretions: 1. Their folution in water 
reddens turnfole paper. 2. They give the pruffic acid by 
diftillation, and by the attion of the nitric acid. 3. The 
calculus of the human bladder contains but little hydrogen, 
fince it gives but little oil; and but little oxygen, fince it 
furnifhes but a very {mall proportion of the pruffic and 
carbonic acids, 
The experiments which I afterwards defcribed on the four 
ealculi carefully treated by different agents, may be taken, 
according to all the other experiments, which I did not 
think it neceffary to defcribe in the fame manner, as an ac- 
count of the properties of the urinary calculus confidered as 
a genus; and I muft indeed here obferve, there are none of 
them which do not prefent refults more or, lefs fimilar. 
‘Thus: 1. The augmentation of its weight, in water, into 
which the calculus was entirely immerfed. 2. The earthy 
4mell of marl which it diffufes, when diluted as a powder in 
‘this liquid. 3. The little alteration it exhibits, and the 
imputrefcibility it preferves during more than: fifteen days 
under water at a temperature above 12 degrees (57° Fahr.). 
4. Its almoft perfe& folubility in 2000 times its weight of 
«water, when repeatedly treated in powder. 5. Its folubility 
in lefs than half that quantity of boiling water; its fepara~ 
tion only partial in Jamellated cryftals by cooling—the man- 
‘ner of obtaining it thus pure. 6. Its property of reddening 
turnfole ‘paper, when after this purification-it 1s rubbed on 
this paper with a little water. 7. Its folution in lime water, 
s whick 
