70 lor. Hare’s Inproved Eudiometers. 
In order to use the Eudiometer, it must be full of water. 
and free from air bubbles, and previously proved air tight,” 
the rod being introduced to its hilt, and the capillary orifice 
open, in consequence of the pressure of the finger on. the 
lever by which it is usually closed. . Being thus prepared, Iet 
us suppose that it were desirable to analyze the atmosphere. 
Draw out the rod 200 measures; a bulk of air, equivalent to 
the portion of rod thus withdrawn, will of course, enter atthe © 
capillary opening; after which the lever must be allowed to 
close it. Introduce the recipient into.a bell glass of hydro- 
gen, and opening the orifice, draw out the rod about 100 de- 
grees; close the orifice, and withdraw the instrument from 
the water. Apply the projecting wires oe severally to the 
solder (in the two furrows in the beam, fig. 2.) communicating 
with the poles of the four calorimotors, then raise the jug so 
as that it may receive one of them, and subject it to the acid. 
By the consequent ignition of the wire, the gas will explode. 
The instrument being plunged again into the water of the. 
pneumatic cistern, so that the eapillary orifice, duly opened, 
may be just below the surface; the.water will enter and fill 
up the vacuity caused by the condensation of the gases. The 
residual air being excluded by the oe. the deficit will be 
equivalent in bulk, to the e portion of the rod remaining with- 
out; and its ratio to the air subjected to analysis, may be 
known by inspecting the graduation. 
In the case of the gaseous mixtures above described, ie 
deficit has, in my experiments, been 126 measures. Where- 
— 
*-Fo prepare the instrument and prove it to be im order, depress the 
ian receiver below the surface of the water in the prema pep 
the capillary orifice being uppermos of 
its tube, and — it ae so tig at wa “trae, a partion of 
water may pass in, and a portion of air may pa uring this = 
— the instrument should be occasionally held it in i a ‘a postare, as 
the air may rise into: the a be aos ga which its ex 
its ts place ‘This degree of Pk nn is easily sustaifed in a well-made 
cg ae iy * 
en 
