) 
Condensation & Rarefaction of Air. By 
degree, I proceeded to ascertain several facts 
experimentally. 
EXPERIMENT 1. 
. Took a receiver, the capacity of which was 
about 120 cubic inches, and suspended the ther- 
mometer with its clear bulb in the central part 
of it; then letting the whole acquire the tem.- 
perature of the room, which was without a fire, 
I exhausted the air and afterwards restored it, 
marking the effects upon the thermometer. The 
medium of several trials nearly agreeing with 
each other was as under: 
The Thermometer 
in the air of the room stood at..-.36°.8 
sunk upon exhaustion tO -s.----+---- 34 +7 
rose when the air was restored to.-38 .g 
The suddenness of the fall and rise puzzled me 
most: after reflecting upon it for some time, 
I conjectured that the real change of tempera- 
ture of the air or medium was much greater than 
the thermometer indicated, but that the ine- 
quality existed only for a few seconds of time, 
because the receiver, &c. immediately impart 
heat to ‘or abstract it from so small a quantity 
of air as 120 cubic inches, which are only equal — 
to 40 erains in weight,—The phenomena of the 
