the Point of Congelation. 2 9 9 
fiaiple ratio would hold good, or any new law take place. To 
bring this to the tell: of experiment, I took a faturated folutiou 
of nitre, whofe freezing point of courfe was between 26° and 
2 7° : an ^ adding to it the purified common fait in various pro- 
portions, 1 obtained the following re fults. 
-O 
Compound folution of nitre and common fait. 
Proportion of 
water to the 
nitre. 
A fa tu rated 
folution. 
Proportion of 
| Freezing 
Freezing 
1 
Difference. 
water to the 
point by the 
point by 
common fait. 
experiment. 
calculation. 
O 
O 
0 
30,2 : 1 
2 1 7 
z yz 
22| 
3 
4 
J 5 : 1 
20 1 
l 9 
if 
10 : 1 
* 7 i 
0 L 
~ 4 
7 A : 1 
l 3 i 
1 1 1 
2 
5 : 1 
5 * 
4 
1 1 
1 he folution of nitre was one that had been made fome 
time, and contained near one-fixth part of nitre, confequently 
more than the water could keep diffolved in the temperature of 
the atmolphere, which was then not much above 40°. Some 
of it therefore was depolited at the bottom. This, however, 
the addition of a T V part of common fait foon enabled the water 
to take up, and the two falts formed together a clear folution. 
In the frigorific mixture, before the congelation took place, 
fome faline cryftals were again depolited, which feemed to be 
chiefly, if not entirely, nitre. In the temperature of the air 
this depolit was re-diflolved ; and on attending to the circum- 
ftances more carefully, upon a repetition of the cooling, I 
found, that no fait began to be depolited till the folution was 
reduced to 23°, when fome needle-like cryftals appeared, which 
confequently were nitre. The folution cooled about a degree 
more, and then, having let fall much fait, partly as cryftals 
Vol. LXXVIII. S f and 
