On the A?2tfnai CalculuL 227 
5. An Hour and half after that, I poured 
into the Flask fome more Water, which was 
much cooler, than what was poured in be- 
fore : As foon as the Water boiled, I expefted 
Air would arife again from the Gravel ; but 
none rofe till it boihd a confiderable time : 
Then I took out the Gravel and found it 
wafted two thirds : But the very hard Calculm 
was not fenfibly wafted, notwithftanding fome 
Air arofe from that alfo in boiling. 
4. I repeated the fame Experiment, with 
two other large hard Gravel Stones, and a 
Piece of RheniJJj Tartar^ which was diflblv'd 
in a Quarter of an Hour, and found that when 
the Flask was filled up with very hot Water, 
then Air arofe from the Gravel, foon after the 
Water began to boil again : But when what 
was wafted by boiling, was filled up with 
cold Water, then no Air arofe from the Gra- 
vel, till it had boiled a long time. 
5. Hence we fee how the Alternacies of hot 
and cold, warm and cool, as they fix the Parts 
of the Gravel and thereby hinder their ari- 
fing from it in the Form of Air, fo they con- 
duce much to the hardening of fome Bodies. 
Thus the Parts of Animals and Vegetables do 
gradually coalefce, and the Calculus hardens 
2. more 
