Experiments on freezing Mixtures • 255 
quantity of fnow ufed was pretty exactly ^ of the weight of 
the acid, the weight of the acid being 13 oz. fo that the 
ftrength of the diluted acid was reduced to ,411. 
The acid before the addition of fnow had no figns of freez- 
ing, its temperature being in all probability much above its 
freezing point ; yet the fnow did not appear to diflblve, but 
formed thin white cakes, which however did not float on the 
furface, but fell to the bottom, and when broke by the fpa- 
tula formed a gritty fediment ; fo that it appears, that thefe 
cakes are not Amply undiflblved fnow, but that the adjoining 
acid abforbed fo much of the fnow in contact with it, as to 
become diluted fufficiently to freeze with that degree of cold, 
and then congealed into thefe cakes. The quantity of con- 
gealed matter feems to have kept increaflng till the end of the 
experiment. 
14. On Dec. 21, an experiment was made in the fame 
manner with the dephlogifticated fpirit of nitre N° 27. The 
acid began to freeze in pouring it into the jar in which the 
mixture was to be made, and flood ftationary there at — 19°, as 
related in Art. 6.; fo that the liquor at the beginning of the 
experiment was white and thick, which made the effect of the 
addition of the fnow lefs fenfible. However, the congealed 
matter conftantly fubfided to the bottom, and the quantity 
feems to have continued inc'reafing to the end of the experi- 
ment. The heat of the mixture rofe to — 4 0 before cold began 
to be produced, and the quantity of fnow added was -W °f 
that of the acid, fo that the ftrength of the acid was reduced 
to ,437 by the dilution. 
A very remarkable circumftance in this experiment is, that 
the acid, while the fnow was adding, firft became of a yel— 
lowifhj, 
