88 EFFLORESCING PROPERTIES 
Soda exposed to the same atmosphere; and, as 
might have been expected from the result of the 
experiment on the crystals, this salt gained 
water. On the 5th, it was found to have gained 
1; grain: on the 11th 64 grains: on the 16th 
9} grains: and on the 4th December 19 grains: 
had I continued the exposure, it would un- 
doubtedly have become of the same constitution 
as the crystals. 
The conclusion to be drawn from the results 
I have now stated, is that the crystals of Carbo- 
nate of Soda begin to effloresce at the temper- 
ature of 58° when the vapour point is at 48°: 
and that crystals of Sulphate of Soda begin to 
effloresce at the temperature of 58° when the 
vapour point is at 49°: and, therefore, that the 
carbonate may be left exposed to the atmosphere 
at the temperature of 58° when the vapour point 
is not lower than 49°, and the sulphate when 
the vapour point is not lower than 50°, without 
any of their water of crystallization being lost : 
and, since the atmosphere in those states of 
dryness is capable of evaporating uncombined 
water, we have beautiful means afforded of pro- 
viding ourselves with the salts in question free 
from any water not belonging to the constitu- 
tion of the crystals, but at the same time with 
