Fal 
_ Prof. Graham, President of the Section, opened the meeting 
% 
114 British Association for the Advancement of Science. 
mode of conception was arbitrary, and the argument founded 
upon it, baseless; for if we investigate the relation between the 
height of any point in the atmosphere, and the density of the air 
at that point, on the supposition that the compressing force is as 
the nth power of the density, we find that the density vanishes 
‘at a finite height whenever m is greater than unity. Therefore, 
though the atmosphere do not consist of indivisible particles, it 
will still have a finite surface. In fact, the finite surface of the 
Z atmosphere no more proves the atomic constitution of air, than 
‘the finite surface of water, ina vessel, proves the atomic constitu- 
tion of water. 
Section B. Chemistry and Mineralogy. ‘ 
with some observations on the recent progress of chemistry, 
which, in his view, is advancing with unprecedented rapidity, 
both in its theory and its applications. ‘The organic department 
is the most productive, and at present engrosses the attention of 
chemists. In this department he would allude to what ‘seemed 
to him its two great features. 1. The happy generalization of 
Dumas,—the law of substitutions, which had been the clue to s0 _ 
many discoveries. He first applied it to the action of chlorine 
upon organic compounds, finding that when chlorine acts upon 
those bodies, for every atom of hydrogen abstracted in the form 
of frydrochiotiv acid, an atom of chlorine is left in its place. The 
same doctrine has been successfully applied to the action of oxy-~ 
gen and other elements on the same bodies. Thus, in the oxi 
dation of alcohol in the acetous fermentation, hydrogen is with- 
drawn in the form of water, by combining with oxygen, and at 
the same time the hydrogen is replaced by an exactly equivalent 
quantity of oxygen. The same law led M. Dumas to his most 
recent discovery, that of chloro-acetic acid,—an acetic acid, in 
which chlorine is substituted for oxygen. One of the most in- 
teresting applications of this doctrine is that by M. Regnault, in 
elucidating the history of the chlorides of carbon. For the orig- 
inal discovery of these compounds we are indebted to Mr. Fara 
day. One of them which contains its two elements in the ratio 
of ae a has been named the protochloride of carbon. 
What is its real nature? M. Regnault has traced it through v® 
» Hotiesomnyatay all produced by the action of chlorine on ole 
ree oe 
