302 Dr. Blagden’s .Experiments on 
ihew, their full effect in depreffing the point of congelation. 
When the folution's- at length froze, after cooling many de- 
grees below the freezing point, the cryftals Riot in a very beau- 
tiful manner round the bulb and up the Idem of the thermo- 
meter. 
In a compound folution of Rochelle and. common fait there 
was, however, a deficiency of effedt. For the folution of 
Rochelie fait in the proportion of one part to four of water, 
having its freezing point at 2 6°f- ; when common fait was 
diffolved in it, in the proportion of T i tf th, the freezing point 
appeared by experiment to be i6°f, whereas by calculation it 
lhould have been dep refed nearly to 1 5 0 . 
A compoftion of three falts was affedted as follows r 
Compound folution of Rochelle fait, common fait, and fal 
ammoniac. 
Proportion 
of water to 
the Rochelle 
fait. 
Proportion 
of water to 
the common 
fait. 
Proportion 
of water to 
the fal am- 
moniac. 
Freezing 
point by the 
experiment. 
Freezing 
point by 
calculation. 
* 
Difference. 
9,8 : 1 
10 : 1 
17 : 1 
O 
0 
, Ilf 
O 
“ If 
The computation is made thus : Rochelle fait, in the pro- 
portion of 1 : 9,8, depreffes the freezing point ; common 
fait, in the proportion of 1 : 10, finks it ii°| ; and fal am- 
moniac, in the proportion of 1 : 17, finks it 7 0 ; now 2|-f- 
1 1 i + 7 = 2o\ ; which, fubtradted from 32, leaves I i r f for the 
computed freezing point of this mixture. 
The moment I had found by experiment that the addition 
of a different fait to the faturated folution of any fait would 
Rill further deprefs its freezing point, it was obvious to con- 
7 elude, 
