feme 'Thermometrical Experiments. 515 
atmofphere was fomevvhat hotter than temperate, and that 
without blowing upon the thermometer. 
W hen the ether is very good, viz . is capable of diffolving; 
elaftic gum, and the thermometer has a fmall bulb, not above 
twenty drops of ether are required to produce this effefit, and 
about two minutes of time ; but when the ether is of the 
common fort, a greater quantity of it, and a longer time,, is 
neceflfary to be employed, though at laft the thermometer is- 
brought down very nearly as low by this as by the beft fort of 
ether. 
In order to freeze water by the evaporation of ether, I take 
a thin glafs tube about four inches long and about one-fifth of 
an inch in diameter, hermetically clofed at one end, and put a 
little water in it, fo as to fill about half an inch length of it, 
as is lhewn at CB in the figure. Into this tube a {lender wire 
H is alfo introduced, the lower extremity of which is twifted 
in a lpiral manner, and ferves to draw up the ice, when formed. 
Things being thus prepared, I hold the glafs tube by its upper 
part A with the fingers of the left hand, and keep it continually 
and gently turning round its axis, firfl: one w T ay, and then the 
contrary ; whilft with the right hand I hold the phial contain- 
ing the ether in fuch a manner as to direfit the ftream of ether 
on the outfide of the tube, and a little above the furface of the 
water in it. The capillary aperture D fhould be kept almoft 
in contafit with the furface of the tube that contains the. 
water. Continuing this operation for two or three minutes,., 
the water will be froze as it were in an inftant ; fince it will 
appear to become opaque at the bottom B, and the opacity will 
afeend at C in lefs than half a fecond of time, which exhibits 
a beautiful appearance. This congelation, however, is only 
fuperficial, and in order to congeal the whole quantity of wa- 
ter,. 
