78 General Reflections on Heat. 
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 
dissolved sulphurets, or with solutions of iron, impregnated 
with nitric oxide in the following way. Let a smail phial, 
with a mouth large enough freely to admit the point of the 
Eudiometer, be filled with the solution to be used. Intro- 
duce into the bottle, over the pneumatic cistern, 300 mea- 
sures of the air or gas to be examined. Transfer the bottle, 
still inverted, toa 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 safficient number of satisfactory 
observations with the various Eudiometers, of which | have 
now given an account, I will send them to you for publication. 
Art. X.—General Reflections on Heat. 
TO THE EDITOR OF THE AMERICAN JOURNAL OF SCIENCES 
DEAR Sir, 
Tue following observations on heat, formed originally 
one of the concluding lectures of a course of chemical instruc- 
tion. I beg leave to retain the form in which it was address- 
ed to my pupils, on account of the difficulty I have experi- 
enced in attempting to mould the matter into the shape of an 
essay. Iam induced to offer it for publication, not with the 
hope of instructing proficients in the science of Chemistry, 
(who will find in it little that is new) but with the belief that 
it presents some considerations, which may be interesting te 
another class of your readers, who are not professionally de- 
voted to this science. 
Most respectfully yours 
: Le le 
