44 Improved Eudiometrical Apparatus, by Dr. Hare. 
the thermometer be at the same height as before the explo- 
sion. 
From this account of the barometer gage eudiometer, and 
those previously given of the sliding rod instruments, it must 
be evident that I have contrived three methods of analyzing 
the atmosphere, or other mixtures containing oxygen, or hy- 
drogen gas. 
In the barometer gage instrument, the deficit is known by 
its effect upon the mercury in the gage tube; i one of the 
sliding rod instruments, the deficit is compensated by water, 
and the quantity of this liquid, which enters ei this purpose, 
is known by the portion of the sliding rod which remains 
without, after excluding the residual gas. In the instrument 
with the sliding rod and gage, the deficit is compensated by 
introducing the rod, the gage enabling us to know when it 
has been introduced sufliciently ; while 1 the graduation shows 
the ratio of the gaseous matter condensed, to the quantity 
confined. — 
When the diversity of these methods is considered, it is 
sap to observe but little difference i in the results obtained 
by them 
A great number of experiments performed by means of 
the barometer gage eudiometer, or those of the sliding rod 
constructior r, and over mercury, gave e 20555 as 
the ty of oxygen in 100 parts of the air. In twenty 
experiments. the greatest discordancy did not amount to yo'o0 
part in 100 measures of air. 
I am now constructing a barometer gage eudiometer, in 
which I mean to use phosphorus to abstract the oxygen, 1 
have already performed some experiments with one of this 
kind, but owing to defects in the process, which I haye ne. 
doubt of Basen the results were not satisfactory. 
= =o Ne 
