280 Dr. Hare’s Improved Barometer Gage Eudiometer. 
Agreeably to the late investigations of the celebrated Faraday, 
equal quantities of the electric fluid are evolved by analogous chem- 
ical changes, in equivalent weights of different ponderable bodies. 
It may therefore be inferred, that in entering into combination the 
electric fluid is obedient to those Jaws of definite proportion which 
regulate other substances. 
t may be imagined, perhaps, agreeably to the undulatory theory, 
that the undulations produced at the non-luminous point are such as 
to destroy each other, But this I conceive would be a surmise re- 
quiring proof, rather than a fact on which to found an opinion. 
Art. VI.—Of ~ i a Barometer Gage Eudiometer; by 
. R. Hare, M.D., &c. &e. 
Axourt nine years ago* I published an account of a hydro-oxygen 
eudiometer, in which the measurement of the gases was effected by 
means of a barometer gage. In the apparatus then employed, the 
receiver was of im and was, of course, fragile. Subsequently I 
— a stout iron bottle in lieu of the glass. 
‘constituents of this apparatus are an air tight vessel, 
piri strong, and having screw apertures for the insertion of 
valve cocks, V V V, a thermometer T, and a galvano ignition appa- 
ratust W W ; also a barometer gage G, vacant by a leaden 
tube with the vessel through one of the valve coc 
An air pump, pneumatic cistern or trough, and reservoirs for gas, 
are necessary auxiliaries. 
It is an important characteristic of the barometer gage eudiometer, 
that it is applicable on a much larger scale than any other. . It is 
only necessary to make the requisite apertures, and tap them for ap- 
propriate screws, in order to transfer the valve cocks, thermometer 
and ignition apparatus, with all the essential means of operating, to 
any air tight cylinder of any size; to a large cannon for instance, the 
mouth being closed. The sources of inaccuracy, if any exist, must 
lessen in proportion to the result, as the quantity acted upon is aug- 
mented. It would, of course, be safer to extend the cylinder 
na than in diameter. 
wit oe ne reader of the article then published, will excnse some repetition, as oth- 
erwise apparatus i in its improved form could not be. made intelligible to those 
t This isthe name by which I ntedesignniot tiny text book. 
