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SECOND REPORT—1 832 
is the only exception which occurs to me. In the last volume 
he has given a valuable though somewhat brief and incomplete 
view of the present state of Meteorology, and particularly of 
the electricity of the atmosphere,—a subject to which he has 
carefully attended, and upon which he has published some 
valuable papers. We shall occasionally avail ourselves of the 
information contained in this work, as well as of a useful com¬ 
pendium of facts contained in the article Meteorology in the 
Encyclopedia Metropolitana now in the course of publication. 
Constitution of the Atmosphere . 
The opinion, formerly general, that the atmosphere is a che¬ 
mically combined compound gaseous fluid, consisting of nitro¬ 
gen, oxygen, carbonic acid, and aqueous vapour, has gradually 
given way to the views entertained by Mr. Dalton, that these in¬ 
gredients exist merely in mechanical union, and each in precisely 
the same condition as if it formed a simple atmosphere without 
foreign admixture. The important consequences to which this 
theory leads, have been developed by Mr. Dalton in an interest¬ 
ing paper in the Philosophical Transactions for 1826, part ii. 
p. 174, of the conclusions of which we shall now give a sketch 
nearly in the words of the distinguished author.—He conceives a 
mixed atmosphere composed of a heavy gas such as carbonic 
acid, and a light one such as hydrogen; and after showing the 
consequences, generally, which would result from the intermix¬ 
ture of equally elevated sections of two independent atmospheres 
of these gases placed side by side, each exerting a pressure of 
thirty inches of mercury, he shows that the two gases would be 
mixed in equal volumes at the earth’s surface; that the carbo¬ 
nic acid would diminish rapidly in density, in ascending, and 
terminate at twenty-eight or thirty miles of elevation; whilst the 
hydrogen, diminishing slowly in density, would attain the supe¬ 
rior elevation of eleven or twelve hundred miles. 
Mr. Dalton considers these views established by three ex¬ 
perimentally determined facts. 1st, That two gases combined 
in whatever proportions in a close bottle, are equally diffused 
through one another. 2nd, That if different gases be placed 
together in a bottle with water, and shaken, no pressure of one 
gas upon its surface can confine another gas in the water, each 
acting as a simple and independent atmosphere. 3rd, That 
the quantity and force of vapour of any kind will be the same 
whether there be any air present or none, being entirely regu¬ 
lated by temperature. 
“ From these three facts,” adds Mr. Dalton, “ but more 
especially by the two last, it appears to me as completely de¬ 
monstrated as any physical principle, that whenever two or 
