Jome Experiments made with an Air-pump. 647 
degree of cold by the evaporation of aether under a re- 
ceiver whilft exhaufting. For this purpofe I put the 
aether into a phial, the neck of which was fufficient to 
admit the ball of a thermometer : this being placed on 
the air-pump, under a receiver which had a plate at the 
top, with a wire palling through a collar of leathers; to 
this wire the thermometer was fixed, by which means 
I could eafily dip the ball of the thermometer into the 
aether. 
EXPERIMENT LX. 
The pump was now worked, and whilft the receiver 
was exhaufting, the ball of the thermometer was often 
dipped into the aether; and when the degree of exhauf- 
tion by the barometer-gage was 65 (which was the ut- 
moft in this cafe that the pump would exhauft to) the 
degree of cold indicated by the fall of the quicklilver iir 
the thermometer was 48° below o on Fahrenheit’s 
fcale ; fo that there was a degree of cold produced 103° 
colder than the air in the room where the experiment 
was made, the thermometer in it being at 55° degrees 
above o. The pump was kept continually working for 
half an hour, and the ball of the thermometer often 
dipped into the aether ; but no greater degree of exhaul- 
tion or cold could be produced. The air being let into 
the 
