the Point of Congelation . 281 
fait oppofed fome refinance, or at leaft proved an Impediment, 
to the progrefs of the cryftallization. By ftirring the folution, 
however, when thefe ftellated cryftals once began to form, 
v 
they quickly increafed in bulk, or became more numerous, 
and the liquor afl'umed its freezing temperature. 
4. This fait with fnow, in the manner of frigorific mix^- 
tures, produced a cold of — 4 0 . 
The next fait which I tried for its effect in lowering th« 
freezing point of water, was nitre. It was part of a large 
compound cryftal, or bundle of cryftals, apparently very 
pure, fuch as is ul'ed in manufacturing the belt gunpowder. 
This being mixed with the diftilled water, in different propor- 
tions, the folutions froze according to the following table. 
Nitre.. 
Proportion 
Freezing 
Freezing point 
of water to 
point by the 
by calculation. r 
the fait. 
experiment. 
32 : 1 
30 i 
30I 
24 : 1 
3° 
3° 
16 : 1 
281 
29 
10 : 1 
27 
r*7 I 
8 : 1 
26 
26 
7>9 : 1 
261 
fait depoffted 
7 ; 1 
261 
l'alt depoffted 
f much fait 
6,85 : 1 
27 
1 depoffted. 
The third column is calcu- 
lated from the fifth experi- 
ment, in which the freez- 
ing point of a folution of 
one part of fait in eight or 
water proved to be 26°. 
Nitre is well known to differ from common fait in being 
much more foluble in warm than in cold water. Hence it 
would be nothing remarkable, that the folutions being made in 
water 
