/• j 6 Mr. cavallo’s Account of 
ter, the operation mud be continued one or two minutes 
longer ; after which the wire H will be found to be kept very 
tight by the ice. Now the bottle with the ether is left upon a 
table or other place, and to the outfide of the glafs tube the 
hand mud. be applied for a moment, in order to fofteti the fur- 
face of the ice, which adheres very firmly to the glafs, and 
then pulling the wire H out of the tube, a folid and hard piece 
of ice will come out, fattened to its fpiral extremity. 
Inidead of the wire H fometimes I put a fmall thermo- 
meter into this tube fo as to have its bulb immerfed in the 
water. With this thermometer I have obferved a very re- 
markable phenomenon, which feems to be not explicable 
in the prefent date of knowledge concerning heat and cold. 
This is, that water will freeze in the winter with a lefs de- 
cree of cold than it will in the dimmer, or when the wea- 
ther is hotter : for indance, in the winter the water in the 
tube AB will freeze when the thermometer is about yo° ; but 
In the dimmer, or even when the temperature of the atmo- 
fphere is about 6o°, the quickfilver in the thermomer mud be 
brought ten or fifteen, or even more, degrees below the freezing- 
point, before the water which furrounds the faid thermometer 
will be converted into ice, even fuperficially ; hence it appears, 
that in the dimmer time a greater quantity of ether and longer 
time is required to freez a given quantity of water than in the 
winter, not only becaufe then a greater degree of heat is to be 
overcome, but principally becaufe in the dimmer a much greater 
degree of cold mud be actually produced before the water that 
is kept in it will affiume a folid form. When the temperature 
of the atmofphere has been about 40°, I have froze a quantity 
of water with an equal weight of good ether, but at prefent, 
7 being 
