222 Scientific Intelligence. 
ive. There are, it will be noticed, three columns of calorific 
powers. In each of these the amounts are expressed in centigrade 
heat units, and therefore indicate directly the pounds of water 
which could theoretically be raised from zero to the boiling point 
by the combustion of one hundred pounds of fuel. The first col- 
umn is obtained in the following manner: The amount of combined 
water is found by adding to the oxygen one-eighth its weight of 
hydrogen; the remaining hydrogen is multiplied by 34,462, the num- 
ber of heat units evolved in the combustion of hydrogen; and the 
amount of carbon is, in like manner, multiplied by 8,080, the calorific 
modulus for carbon. The sum of these two products is the number 
of heat units generated by the complete combustion of one unit of 
the fuel, containing the given proportions of carbon and available 
hydrogen. The heat units due to the combustion of the sulphur 
are disregarded, in view of the small amount of sulphur, its low 
calorific capacity (about 2,240 units), and the circumstance that it 
exists partly in the form of pyrites, the decomposition of which 
still further diminishes the amount of heat from this source, and 
partly as sulphuric acid, causing a net loss. 
The second class of calorific powers is obtained by a similar cal- 
culation on the supposition that the moisture is absent. The 
. 
plied by its specific heat. sum of these products, which we 
may call the temperature unit, is the number of heat units required 
to raise the mixt ee in temperature. Dividing the 
_ We have in analysis No. 1 of the table the following constitu- 
tion of the fuel: Carbon, 59°72; hydrogen, 5°08; nitrogen, 1°01 ; 
oxygen, 15°69; sulphur, 3°92; moisture, 8°94; ash, 5°64. To find 
portional amount of hydrogen, or one-eighth, since water C0 
sists of one part hydrogen, and eight parts o 
us 17 ined water, leaving 3°12 of hydrogen available for 
