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X. ’Experiments cn the cooling of Water below its freezing 
Point. By Charles Blagden, M. D. Sec . R. S. and F. A. S. 
Read January 3 r, 1788. 
T T J’HEN the experiments for determining the degree of 
V V cold at which quickfilver becomes folid, related in the 
Philofophical Tran factions for 1783, were under confideration, 
no difficulty occurred in explaining the phenomena that had 
been obferved, except in the few inftances where the mercury 
in the thermometer congealed, whilft it was furrounded with 
fome of the fame metal in a fluid if ate. The well-known pro- 
perty of water, that under different circum fiances it will bear 
to be cooled feveral degrees below its freezing point without 
congealing, afforded from analogy the moft probable folution 
of this difficulty ; but as neither the caul'e of that property 
had been inveffigated, nor the circumftances by which it is 
modified had been afcertained, 1 was led to attempt fome expe- 
riments on the fubjeft ; not only in hopes of elucidating the 
above-mentioned phenomenon of the quickfilver, but alfo 
becaufe this very quality in water was itfelf a curious fubjecf of 
refearch. 
I began with endeavouring to determine, whether this pro- 
perty belongs to it as pure water, or depends upon extraneous 
admixtures. For that purpofe I poured fome clean diftilled 
water into a common tumbler glafs, till it reached two or 
three inches above the bottom, and then fet the glafs in a 
frigorific 
