a new Eudiometer . i c 9 
refpirable. T he firft is what I have commonly ufed, and 
which I fhall firft delcribe. In this method a proper quantity 
of nitrous air is put into one of the bottles M, by means of 
one of the meafures above deferibed, and a proper quantity of 
refpirable is let into the veffel A, by firft filling it with this air. 
and then fetting it on the knob C, as was done by the mea- 
(ure. The veffel A is then fixed in the focket, and the bottle 
M placed with its mouth over the cock. Then on opening the 
cock, the air in the veflel A runs (lowly in (mall bubbles into 
the bottle M, which is kept fhaking all the time bv moving it 
backwards and forwards horizontally while the mouth ftiij 
remains over the cock. 
Notwithstanding the precautions ufed by the Abbe fon~-> 
TMA in meafuring the quantity of air uled, I have lbmetimcs 
found that method liable to very conliderable errors, owing to 
more water flicking to the tides of the meafure and tube at 
one time than at another : for this reafon I determine the 
quantities of air ufed and the diminution, by weighing the 
veflels containing it under water in this manner. From one 
end of a balance, placed fo as to hang over the tub of water, 
is fufpended a forked wire, to each end of which fork is fixed a 
fine copper wire ; and in trying the experiment the veflel A, 
with the refpirable air in if, is fir ft weighed, by fu (pen ding it 
from one of thele copper wires, in fuch manner as to remain 
intirely under water. The bottle M, with the proper quantity 
of nitrous air in it, is then hung on in the fame manner to the 
other wire, and the weight of both together found. The air 
is then let out of the veffel A into the bottle M, and the 
weight of both veflels together found again, by which the 
diminution of bulk which they fufter on mixing is known. 
Laftlv, the bottle M is taken off, and the veflel A weighed 
rurai n— 
O 
