C O N G E L A T I O N OF QJJ I C K S I L V E R. 247
mometer was derived from this new difcovered principle, namely, c h a p .
the con t raft ion of this metal in freezing, and to try whether pure j
mercury required a greater degree of cold to freeze it than adulterated
mercury, I made the following experiments with the following
forts of mercury:
1. I procured from Mr. Winterberger, a famous chymiil of St.
Peterfburgh, the purefl mercury, known to chymifls, viz. revivified
from calomel by filings of iron. 2. From Dr. Pallas’
native mercury, collected in a mine where no other metal is found
but a little iron. 3. Common barometer mercury, furnifhed by
Mr. Morgan, an Engliih optician at Peterfburgh, juft as he received
it from England for filling his inftruments. 4. Six
drachms of common mercury, wb:ch I adulterated by difiolving
in it a quarter of a grain o f tin foil.
I procured alfo fome thermometers made with great care and
accuracy by Mr. Morgan, filled with the fame purified mercury,
N 0 1. for the exprefs purpofe of thefe experiments; alfo one
with highly re&ified fpirits of wine, diftilled by Mr. Winterberger.
Adjoined is a drawing of the apparatus I employed in thefe
experiments, and which was fuggefted. to me by my learned
friend Dr. Black: it differs fro.na.that employed by Mr. Hutchins
in being more fimple, and confequently the mercury eafier to be.
examined during the procefs of congelation. It con fills of a
half pint water-glafs C, wrapped round with coarfe flannel,
and filled with i uming lpirit of nitre and fiaow to produce arti-
5 ficial: