3 1 o c aventdis H f s Obfervations 
with what I had done, recommended nearly the fame method 
of determining the degree of cold at which mercury freezes. 
Betides the abovemen tioned inftruments, there were lent to 
Mr. iiufCHiNS two fpirit thermometers and a thermometer 
marked C, made at the expence of the Hudfon’s Bay Com- 
pany. The two fpirit thermometers were made at the recom- 
meudation, and under the infpedion of Dr. blagden, and 
w'ere of great ufe, as they ferve to afcertain feveral circum- 
fhnces relating to the experiments, which could not otherwife 
have been determined. The intention of the thermometer C 
will be mentioned in the courfe of this paper. 
Before I enter into the examination of Mr. Hutchins’s ex- 
periments, it will be proper to take notice of a phenomenon 
which occurs in the freezing of water, and is now found to 
take place in that of quickfilver, and which occalioned many 
remarkable appearances in thefe experiments. 
It is well known, that if a veflel of water, with a thermo- 
meter in it, is expoled to the cold, the thermometer will fink 
feveral degrees below the freezing point, efpectally if the water 
is covered up lo as to be defended from the wind, and care is 
taken not to agitate it ; and then, on dropping in a bit of ice, 
or on mere agitation, lpiculae of ice Ihoot fuddenly through the 
water, and the in clo fed thermometer rifes quickly to the freez- 
ing point where it remains ftationary *. 
This 
* Though I here fay conformably to the common opinion, that mere agitation 
may fet the water a freezing, yet fome experiments, lately made by Dr. blag- 
dek, feem to fhew, that it has not much, if any, effect of that kind, otherwife 
than by bringing the water in contact with fome fubftance colder than itfelf. 
Though in general alio the ice {hoots rapidly, and the inclofed thermometer rifes 
very quick ; yet I once obferved it to rife very {lowly, as, to the belt of my 
remembrance, it took up not lefs than half a minute before it rofe to the freezing 
point ; 
