Hydrogen ...........| 20.02| 26.16| 29.03| 35.92 | 9.64| 14.45| Nitrogen ...........| Nil. | Nil. | Nil. | Nil. | 23.41| 2.89| Heat units .........|728,746 |698,852 |627,170 |745,813 |592,380 |745,591 | --------------------+--------+--------+--------+--------+---
-----+--------+

“We will now show how the natural gas compares with coal, weight for weight, or, in other words, how many cubic feet of natural gas contain as many heat units as a given weight of coal, say a ton.  In order to accomplish this end we will be obliged, as I have said before, to assume as a basis for our calculations what I consider a gas of an average chemical composition, viz.: 

Per cent. 
Carbonic acid............................ 0.60
Carbonic oxide........................... 0.60
Oxygen................................... 0.80
Olefiant gas............................. 1.00
Ethylic hydride.......................... 5.00
Marsh gas............................... 67.00
Hydrogen................................ 22.00
Nitrogen................................. 3.00

“Now, by the specific gravity of these gases we find that 100 liters of this gas will weigh 64.8585 grammes, thus: 

Weight,
Liters. grammes.

Marsh gas................. 67.0            48.0256
Olefiant gas..............  1.0             1.2534
Ethylic hydride...........  5.0             6.7200
Hydrogen.................. 22.0             1.9712
Nitrogen..................  3.0             3.7632
Carbonic acid.............  0.6             1.2257
Carbonic oxide............  0.6             0.7526
Oxygen....................  0.8             1.1468
-------
Total................................... 64.8585

“Then, if we take the heat units of these gases, we will find: 

Heat units
Grammes. contained.

Marsh gas................ 48.0256       627,358
Olefiant gas.............  1.2534        14,910
Ethylic hydride..........  6.7200        77,679
Hydrogen.................  1.9712        67,929
Carbonic oxide...........  0.7526         1,808
Nitrogen.................  3.7630         -----
Carbonic acid............  1.2257         -----
Oxygen...................  1.1468         -----
-------       -------
Totals                  64.8585       789,694

“64.8585 grammes are almost exactly 1,000 grains, and 1 cubic foot of this gas will weigh 267.9 grains; then the 100 liters, or 64.8585 grammes, or 1,000 grains, are 3,761 cubic feet; 3,761 cubic feet of this gas contains 789,694 heat units, and 1,000 cubic feet will contain 210,069,604 heat units.  Now, 1,000 cubic feet of this gas will weigh 265,887 grains, or in round numbers 38 lb. avoirdupois.  We find that 64.8585 grammes, or 1,000 grains, of carbon contain 523,046 heat units, and 265,887 grains, or 38 lb., of carbon contain 139,398,896 heat units.  Then 57.25 lb. of carbon contain the same number of heat units as 1,000 cubic feet of the natural gas, viz.,