the Point of Congelation . 301 
depreffing the freezing point. The above-mentioned circum- 
•ftance feems rather contradiaory to an opinion which has been 
entertained, that when one fait, added to a faturated folution 
of another fait, enables it to take up more of the former fait, 
it is only becaufe the water of cry ftallization of the fecond ialt 
really adds to the quantity of the diffolving fluid. 
I next proceeded to try a flmilar experiment with fal ammo- 
niac and the purified common fait, but with this difference, 
that neither fait flaould be added to the water in Inch quantity 
as to come near the point of faturation, fufpeding that the 
diminution of effecff obferved in the foregoing experiments 
might depend, in part at leaft, upon this circumftance. The 
faUmmoniac, therefore, was diffolved in water in the propor- 
tion of 1 : 10, and the correfponding point ot congelation ap- 
peared by experiment to be 20T, agreeing very well with the 
table of fal ammoniac formerly given. To this folution was 
added the purified common fait, in proportion to the water as 
, : ic, and then as. : .0; the refulting points of congelation 
were as is fhewn in the following table, conftrufted 111 al re- 
fpects as the immediately preceding. 
Compound folution of fal ammoniac and common fait. 
Proportion of 
water to the fal 
ammoniac. 
Proportion of 
water to the 
common fait. 
Freezing 
point by the 
experiment. 
Freezing 
point by 
calculation. 
Difference, 
IOII 
10 : 1 
I5*.I 
10 : 1 
O 
I 2 1 
9l 
O 
*3 
9r 
I 
z "3 
Hence it appears, that in this compound folution both falls 
.duced, as exactly as the experiments can be expefted^to 
• S f 2 5 
