40 
heart most deserved our admiration. The world has to 
lament the death of a great and good man, and this Society 
one of its greatest ornaments. 
“Method of Construction of a New Barometer,” by J. P, 
Joule, D.C.L., LL.D., F.B.S., &c., President, 
The condition of the instrument placed on the 18th of 
March in the Society’s Hall proves that it is possible to use 
sulphuric acid on the top of the mercurial column without 
chemical action taking place. I have therefore proceeded 
to prepare other tubes with a view to test, by practical 
work, the merits of the new contrivance. 
A tube of about iV inch bore is selected. It is first 
cleaned by drawing a knotted string through it. It is then 
bent to the siphon shape; and near the longer end it is 
drawn to a capillary tube. It is then washed with nitric 
acid ; afterwards with sulphuric acid. The sulphuric acid 
is then drained off. Mercury is then poured into the short 
limb. The end of the longer limb is then attached to my 
mercurial exhauster. On working this the mercury rises in 
the tube, and, being replenished by pouring it into the short 
limb, soon arrives at the height due to the atmospheric 
pressure. It carries with it the acid left adhering to the 
sides, so that after a few hours half, or, what is better, one 
third of an inch of acid stands above the mercury. Small 
bubbles of air are seen to arise; but by leaving the tube in 
connexion with the exhauster for a day or two these finally 
cease. Mercury is then poured into the short limb until 
that in the longer rises nearly to the capillary part of 
the tube. This is then sealed and detached from the ex- 
hauster. Mercury is then removed from the shorter limb 
until it stands in the long one at a convenient height. 
Sulphuric acid is then introduced into the short limb until it 
forms a column equal to that in the longer limb. A small 
tube is finally attached to the short limb, and dipping a 
