ce 
fully two meafures of any atmo6= 
fpheric air; he takes particular 
care to perform every experiment 
in the fame manner, as well in the 
handling of the inftruments, as im 
the exact time, even to a moment, 
of fhaking the two airs together; — 
of letting ‘the tube fiand by, before 
: he examines the number: pen the 
-brafs feale, 8c. oe 
‘After the whole. operation is fie 
nifhed, he dedu&is the number: of © 
the fub-divifions of the whole co+ 
lumn of air remaining in the tube 
from the number of all the fub- 
divifions or parts of both airs which - 
were let up; and the refult gives 
exactly. the number of parts or fub-. 
divifions which were deftroyed; 
for inftance, if, after the third meas _ 
=. fare of nitrous air being let up, the — 
- mext mark of the tube sorrefponds eee 
= WHE 
~ 
