384 
This is equals taking the latent caloric of steam at 1000, to 
the evaporation of 5.175 of water already boiling* Carbon, 
when fully burnt, forms carbonic acid, and combines with two 
atoms of oxygen, or 6 parts with 16. 
88 parts, therefore, will combine with 234.6 and evaporate 1214.4 of water.t 
Hydrogen combines with 8 times its 
weight of Oxygen, forming water. 
5^ parts, therefore, combine with ... 42. Oxygen, & evaporate 217.35 „ 
Total 276.6 Oxygen combined 1431.75 of water 
evaporated by 100 combustible portion of 100 parts of coal. 
From this, a small deduction, the amount of which the 
analysis does not enable us to state exactly, is to be made for 
sulphur, (disregarded by many in such analyses, but un- 
doubtedly present,) and for oxygen already existing in the 
coal. The amount cannot be so much as 5^ parts of oxygen, 
or 27 parts of water evaporated. 
Coal is stated by practical men with whom I have con- 
versed, to leave rather more than half its weight of coke; 
then deducting two parts for ashes, 48 parts combine with 
128 oxygen, and evaporate 662.4 of water. Experiments 
in the laboratory give 62.5 ; deducting 2.5 for ashes and 
other impurities, we should have 160 oxygen consumed, 828 
water evaporated. 
It appears, therefore, that coal, when burnt in such modes 
as to render all its combustible matter available to the fullest 
extent, must yield about twice the heat which can be given 
out by the coke alone resulting from it. Whether smelting 
furnaces, foundries, locomotive engines, and the other fires 
where coke is burnt, any or all of them, oppose difficulties 
to the application of such modes, which it is beyond the union 
of science with practical skill to surmount, remains yet to be 
decided. 
* For, as 1000 : 28.75 : : (212 — 32 = ) 180 : 5.175. 
t As 6 : 16 : : 88 : 234.6, and 234.6 multiplied by 5.175 gives 1584. 
