[ ii6 ] 
that dry air does not communicate its heat like air fatu-' 
rated with moifture; and that the evaporation from the 
-body, which takes place when the air is dry, affifts its 
living powers in producing cold. It muft be imme- 
diately perceived, that, befides the principal objedt, thefe 
curious experiments throw great light on many other 
very important fubjedls of natural philofophy. 
January 23. The honourable Captain phipps, Mr. 
BANKS, Dr. SOLANDER, and myfelf, attended Dr. for- 
DYCE to the heated chamber, which had ferved for many 
of his experiments with dry air. We went in without 
taking off any of our cloaths. It was an oblong-fquare 
room, fourteen feet by twelve in length and width, and 
eleven in height, heated l)y around ftove, or cockle^ of calf 
iron, which flood in the middle, with a tube for the fmoke 
carried from it through one of the lide walls. When we 
lirll entered the room, about 2 o’clock in the afternoon, 
the quicklilver in a thermometer which had been fuf- 
pended there Hood above the 1 50th degree. By placing 
feveral thermometers in different parts of the room we 
afterwards found, that the heat was a little greater in 
fome places than in others ; but that the whole difference 
never exceeded 20°. We continued in the room above 
20 minutes, in which time the heat had rifen about 12°, 
chiefly during the firft part of our Hay. Within an 
hour afterwards we went into this room again, without 
feeling any material difference, though the heat was con- 
fiderably increafed. Upon entering the room a third 
time, between five and fix o’clock after dinner, v/e ob- 
ferved 
