[ 3°3 ] 
XX. Obf ovations on Mr. Hutchins’s Experiments far determining 
the Degree of Cold at which Quickfilver freezes. By Henry 
Cavendifh, Efq. F. R . S. 
Read May i, 1^83. 
t | ^ HE defign of the following paper is to explain feme par* 
JL ticulars in the apparatus fent by me to Mr. hutchins, 
the intention of which does not readily appear ; and alfo to 
endeavour to fhew the caufe of fome phenomena which occurred 
in his experiments ; and point out the confequences to be drawn 
from them. 
This apparatus was intended to determine the precife degree 
of cold at which quickfilver freezes : it confided of a final! 
mercurial thermometer, the bulb of which reached about 2-f 
inches below the fcale, and was inclofed in a glafs cylinder 
fwelled at bottom into a ball, which, when ufed, was filed 
with quickfilver, fo that the bulb of the thermometer was in- 
tirely furrounded with it. If this cylinder is immerfed in a 
freezing mixture till great part of the quickfilver in it is frozen, 
it is evident, that the degree fhewn at that time by the inclofed 
thermometer is the precife point at which mercury freezes ; for 
as in this cafe the ball of the thermometer mud be furrounded 
for fome time with quickfilver, part of which is a (dually frozen, 
it feems impoffible, that the thermometer (hould be fenfibly 
above that point ; and while any of the quickfilver in the cy- 
linder remains fluid, it is impoffible that it ffiouid fink fenfibly 
Vol. LXXI 1 I. S f below 
