baproved Eudiometrical Apparatus, by Dr. Hare. 43 
With the gage tube is associated a scale, divided into 450 
equal parts. Instead of inhaling, successively, due portions 
ef hydrogen and atmospheric air, as heretofore described, I 
have found it better to mix them previously in known vol- 
umes, by means of the volumeters described in articles 19 
and 20.* Having, by the aid of one of those instruments, 
made a mixture of one part of hydrogen with two of atmos- 
procuring such mixtures, is preferable, from its saving trou- 
le, and lessening the chances of error in the measurement ; 
and because the gaseous fluids become more thoroughl. 
blended; a result which does not follow their admixture, as 
immediately as might be expected. 
aving prepared a mixture of two volumes of atmospheric 
air, with one of hydrogen, and the receiver being exhausted 
as far as practicable, if any small quantity of the mixture be 
exploded in it, by exciting ignition in the platina wire, all the 
oxygen will be condensed. e residuum, consisting of hy- 
drogen and nitrogen, will not interfere with the result of any 
subsequent experiment, although the receiver should not be 
thoroughly exhausted. Under these circumstances, let the 
exhaustion be carried to 400°, and let 300 measures of t 
mixture enter, so as to depress the mercury in the gage to 
100 on the scale. An explosion being effected, the mercury 
shall have regained its previous temperature, will be found 
somewhat above 220°. i 
Of course there will be a deficit produced of more than 
120 parts, of hich one-third, or a little more than 40 parts, 
will be the quantity of oxygen in 200 parts of the air, snb- 
jected to analysis. 
n order to ascertain the influence of temperature, a ther- 
mometer is placed in the receiver, the state of which is noted 
before and after explosion ; and the deficit is estimated, 
either by allowing for the difference produced by the tempe- 
ature, or awaiting the refrigeration, until the mercury in 
* Of the engravings and descriptions of apparatus used in the chemical 
course of the University of Pennsylvania. 
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