CADY AND MCFARLAND.| Composition of Natural Gas. 233 
per cent. as much water per 1000 cubic feet—that is, 95 
pounds, or 11.4 gallons. 
This shows that the production of a large quantity of water 
is an inevitable accompaniment of the combustion of natural 
gas, and it is no evidence of the good or bad quality of the gas 
itself, excepting that the quantity of water thus produced in- 
creases as the percentage of methane in the gas increases. It 
should therefore be considered rather a sign of good quality 
than of bad. The heat of combustion of methane is 966 British 
thermal units per cubic foot of gas, or 8598 kilogram calories 
per cubic meter.!"4 
ETHANE.—HEthane, C2He, the next member of the marsh-gas 
series, is sometimes found in considerable quantities in natural 
gas. It greatly resembles methane in its general properties, 
being a better fuel and burning with a slightly luminous flame, 
which makes it a better illuminant than methane. The heat 
value per cubic foot is 1728 British thermal units, or 15,387 
kilogram calories per cubic meter. 
Ethane contains 79.96 per cent. of carbon and 20.04 per 
cent. of hydrogen by weight. It boils at —93° C. under 760 
millimeters pressure. 
HIGHER HYDROCARBONS OF THE PARAFFIN SERIES.—Several 
more of the members of this series of hydrocarbons are found 
in small quantities in some samples of natural gas. As the 
members of the series increase in carbon contents and decrease 
in hydrogen there is a gradual change in properties. Some of 
the lower members of the series are: 
Formula, gntont | taawowes. "pot 
| | 
eRODANCM Ae) ye ee Celalg | 81.78 18.22 —45° C. 
IBUtanene es oe. CsHi0 | 82.72 17.22 +. 1° C; 
Rentancmnemien) ss. 41. CsHie | 83.19 16.81 +388° C. 
As is seen in the above table, the boiling-points of these hy- 
drocarbons rise with the increasing percentage of carbon, and 
consequently pentane and all of the still higher members of the 
series are liquids under ordinary conditions. These form the 
principal ingredients of petroleum. Their density and illumi- 
nating power increase in the same proportion and the odor 
grows stronger. The slight odor, resembling that of gasoline, 
114. See Richard’s Metallurgical Calculations, vol. 1, p. 31. 
