598 On the Expansion of Elastic Fluids by’ Heat. 
blow-pipe, and let down a small column of mer- 
cury to the proper point. 
When'the manometer was to be exposed’ to 
a heat of 212°, I used a Florence flask, with a 
long glass tube corked into it, in such sort that 
as much of the manometer as was necessary to 
be exposed ta the temperature might be in the 
tube; then water at the bottom of the flask was 
made to boil violently, so that a constant stream 
of vapour issued out of the top of the glass tube, 
which was found to raise the thermometer to 
212%. Small specks of white paint were put 
upon the divisions of the manometer together 
_with numbers which were discernible through 
the containing tube. For lower temperatures 
a deep tin vessel containing hot water was used, 
in which the manometer was immersed, the water 
being well agitated previously to each obser - 
vation. ag 
From a great many experiments made in 
this way on common air, and likewise upon 
hydrogenous gas, oxygenous and nitrous gases, 
and carbonic acid gas, I can assert that the con- 
clusions of De Luc, Roi, Saussure, Berthollet, 
&c. are nearly accurate throughout, and that 
those of de Morveau and du Vernois are ex- 
tremely inaccurate in the higher temperatures. 
I have repeatedly found that 1000 parts of 
common air of the temperature 55° and common 
