Experiments on the freezing of piculs. iy$ 
It may be obferved, that the freezing point of N° 7. tried 
in the firft way, is confiderably above that correfponding to the 
ftrength of the whole mafs ; but as this experiment was fhewn 
(in p. 1 73.) to be doubtful, and not unlikely to exceed the 
truth, we may fafely reje£f it as erroneous. All the others, 
as might be expedf d, are lower than thofe correfponding to 
the ftrength of the whole mafs, and above thofe obferved in 
the fecond manner, and therefore ferve to confirm the truth of 
the above determination of the freezing points of fpirit of 
nitre ; and alfo (hew, that in this acid the point of fpirituous 
congelation is pretty regular, and does not depend much, if 
at all, on the rapidity with which the congelation is performed. 
The point of aqueous congelation, however, feems liable to 
confiderable irregularity ; for N° 13. after having been expofed 
to the cold, froze on agitation, the congelation, as was before 
faid, being of the aqueous kind, and the thermometer flood 
flationary therein at — 34 0 . The ice being then almofl melted, 
it was again expofed to the cold, till a good deal was frozen ; 
but yet its temperature was then no lower than - 32°!, 
though the quantity of frozen matter muff certainly have been 
much more than in the firft trial. The fluid part being then 
decanted, and the frozen part melted, both were again expofed 
to the cold. They both were made to congeal by agitation, 
and the temperature of the undecanted was then found to be 
— 35 0 , and that of the decanted part —37°** fo that it Ihould. 
feem as if the freezing point found by the hafty congelation 
was always lower than that found the other way, which may, 
perhaps, proceed from this caufe ; namely, that when fufli- 
cient time is allowed, the watery part will feparate from the 
reft, and freeze in a degree of cold much lefs than what is 
2 required.. 
