30 Dr. Hare’s improved Eudiometers. 
3 I 
TM 
aT — 
= ETI 
ATT TR 
This vessel being filled with water, and immersed in the 
pneumatic cistern, the apex being just even with the surface 
of the water, one hundred measures of atmospheric air, and a 
like quantity of nitric oxide, are to be successively introduced. 
The residual air may then be drawn into the eudiometer, and 
ejected again into the receiver through the water, to promote 
the absorption of the nitrous acid produced. Lastly, it may 
be measured by drawing it into the instrument, and ejecting 
it into the ege-shaped receiver (fig. 8), or into the air, when 
the quantity of it will appear from the number of degrees 
which the sliding-rod enters during the ejection. That in this 
way gas may be measured with great accuracy may be de- 
monstrated by transferring any number of measures, taken 
separately, into the semi-oval receiver, and subsequently re- 
measuring them. 
The eudiometers (figs. 6 and 7), with the accompanying 
semi-oval glass vessel (fig. 8), may be employed with the dis- 
solved sulphurets, or with solutions of iron,.impregnated with 
nitric oxide in the following way. Let a small phial, with a 
mouth large enough freely to admit the point of the eudiome- 
ter, be filled with the solution to be used. Introduce into the 
bottle, over the pneumatic cistern, 300 measures of the air or 
gas to be examined. ‘Transfer the bottle, still inverted, to a 
small vessel containing water, or a quantity of the absorbing 
fluid used in the bottle, adequate to cover the mouth of the 
phial and compensate the absorption. When there has been 
time enough for the absorption to be completed, transfer the 
residuum to the receiver (fig. 8), and measure as in the case 
of nitric oxide. 
As soon as I can make a sufficient number of satisfactory 
observations with the various eudiometers of which I have 
now given an account, I will send them to you for publica- 
tion. 
III. On 
