On the Animal Calculus. 197 
there is ftore of unelaflick Air Particles in it, 
which are raifed in Diftillation into an elafhic 
State, at the fame time that the volatile Salt a- 
rifes in white Fumes, an Argument that they 
are intimately combined with each other in the 
Calculus. 
10. And it was this Confideration, which 
put me upon making (bme Attempts, to try by 
Variety of fermenting Mixtures, whether the 
brisk Adion of fome Fermentations, might 
not poflibly fo (hake and roufe thefe Air Par- 
ticles, as to make them fly off into an elaftic 
State, and thereby diflblve the Union of the 
Parts of the Stone. We find that Spirit of 
Nitre acts in this manner on the Calculus^ 
in the DiflTolutioii of it ; for we fee in Ex^ 
periment I. Numb. 4. that a hundred and fif- 
teen Grains or about 7 of a cubic Inch of 
CalculuSy when diflblved in Spirit of Nitre, 
generated forty eight cubic Inches of Air, with 
a large Froth, a Quantity equal to a hundred 
and forty four times the Bulk of the Calculus. 
11. From the few Tryals I have hitherto 
made, I have found a ferrnenting Mixture, 
w^hich by its vigorous Adion, not only throws 
off elaftic Air from many human Calculi^ but 
alfo very fenfibly waftesand diftblves feveral of 
O 5 thofe ' 
