Ta Br. Hare's knproved Eudiomeiers. 
Big. &. 
The method of analyzing atmospherie air by means of these 
instruments, is as follows. Supply the subsidiary Eudiome- 
ter with its complemept of hydrogen gas, by introducing the 
apex of the glass recipient into a bell glass containing, over 
mercury, the gas in question, and drawing out the sliding 
rod, the orifice being kept open only while above the surface 
of the mercury, and inside of the bell. 
The gauge cock (C, fig. 4.) of the principal Eudiometer 
being closed, and that which opens a communication between 
the recipient and the funnel F open, and the instrument 
having been previously thoroughly filled with mercury, and 
placed over the mercurial cistern, as already mentioned, in- 
troduce into it, through. the funnel, the gas which had beer 
included in the subsidiary instrument (fig. 5); next shut off 
the communication with the mercurial cistern, re-establish 
those between the recipient and the rod and gauge, and push 
the rod into its tube up to the hilt)’ The re-entrance of the 
rod, by raising-the mercury into the recipient, forces the hy- 
drogen in bubbles through the water of the gauge, and dis- 
places all the atmospheric air which it previously: contained. 
Now shut the passage to the gauge, open that which commu- 
nicates through the funnel with the mercurial cistern, and 
draw out the rod to its utmost extent. Into the Eudiometer 
thus situated and prepared, introduce successively 100 mea- 
sures of hydrogen and 200 measures of atmospheric air, by 
means of the subsidiary Eudiometer: then closing the pas- 
sage to the mercurial cistern, and opening the passage to the 
gauge, push in the rod, until the water in the gauge indicates — 
that the pressure on the gases included is equivalent to that 
of the external air. The gauge cock being closed;+he-gases 
are ready to be exploded. ‘The explosion is produced by 
glvanic ignition, as in the ease of the kudiometer fer water 
