47 
Lancashire, Scotch, and Derbyshire coal. The mean of these 
numbers is as follows: — Carbon, 80*40 ; oxygen, 7*16 ; hydro- 
gen, 5*19. Subtracting from the amount of hydrogen the 
quantity corresponding to 7*16 of oxygen there remain as 
combustible material in one part of coal — carbon, 0*8040 ; 
hydrogen, 0*0421. For combustion it requires 2*4828 parts 
of oxygen, and produces 2*9480 parts of carbonic acid. Sir 
J. Herschel, in his <f Meteorology,” takes as the approximate 
weight of the atmosphere 11 x 10 18 pounds. If we take as 
the amount of oxygen in the atmosphere 23*04 per cent by 
weight, and as the amount of carbonic acid *05 per cent by 
weight, the following numbers are obtained (assuming 
lXlO 14 pounds as the unit of measurement): — Weight of 
atmosphere 110000; oxygen contained *25344, carbonic acid 
contained 55; weight of coal, 98*112; oxygen required for 
combustion, 243*59 ; carbonic acid from combustion of coal, 
289*23 ; total carbonic acid, 344*23 ; ratio of oxygen to 
carbonic acid at present, 4 60 '8 to 1 ; ratio after combustion 
of assumed quantity of fuel, 72*9 to 1. 
The last ratio can of course only be regarded as an approxi- 
mation, but when we take into account all the available fuel 
in the world — wood, peat, lignite, coal, anthracite, also the 
quantity of carbonic acid evolved from volcanic districts — and 
remembering the opinion of a member of this society, that we 
know little about the difficulties likely to be encountered in 
mining operations at a depth of 4,009 feet — there seems little 
reason to doubt that the ratio of the oxygen to carbonic acid 
would be reduced considerably below the number above 
stated, and that the quantity of carbonic acid in the atmo- 
sphere would reach a point much beyond that at which it 
becomes deleterious to human life. It seems then more 
reasonable to take the alternative and maintain that the 
carbonic acid will be de-oxidized, and that there will always 
be an abundance of fuel. 
