3oo Dr. Blagden’s Experiments on 
and partly, by ftirrmg, as a powder, It was made to congeal 
by dropping in a bit of fnow, and the thermometer rofe to 
22°l. When more fait was added, to render its proportion to 
the water as i : i the nitre feemed fill more difficultly depo- 
rted in the freezing mixture ; and this continued to be the 
effect of further additions of fait, the depofftion of faline 
matter previous to the congelation being always lefs, in pro- 
portion as the quantity of common fait was greater. 
It is evident from the freezing points of this compound fo- 
lution, that the common fait depreffed the freezing point of 
the folution of nitre fomething lefs than it would have de- 
preffed the freezing point of water, if added to it in the lame 
proportion. To Ihew this more evidently, I have added a 
fourth and a fifth column to the table: the fourth column is. 
formed by taking the freezing point of the faturated folution 
of nitre as 26T, and then finding how many degrees the 
quantity of common fait added would have depreffed the freez- 
ing point of water ; this number of degrees, fubtraded from 
the conftant number 26° i, gives the freezing point by calcu- 
lation ; namely, what it Ihould have been if the fait had pro- 
duced the fame effed upon the folution of nitre as it would, 
upon pure water ; and the difference between this and the 
freezing point found by the experiment gives the numbers in 
the fifth column. From the table it is apparent, that the defi- 
ciency of effed from the fait goes on increafing to the third 
experiment, after which it aecreafes. Probably fome particular 
law takes place, which it would require a great number of expe- 
riments to develope ; but the decreafe toward the laft may in 
part be owing to the greater quantity of nitre which the water, 
when it began to be loaded with common fait, retained at the 
time of congelation, and which muff have its effed in 
ij depreffing 
