CHAPTER XI
PRODUCER-GAS
It may here be not amiss to point out the differences between illuminating gas and those gases which are called in English "producer" gases, and in French "poor" gases, because of their low calorific value.
Street-Gas.—This gas, the composition of which varies with different localities, has a calorific value, which is a function of its composition, and which varies from 5,000 to 5,600 calories per cubic meter (19,841 to 24,896 B.T.U. per 35.31 cubic feet) measured at constant pressure and corrected to 0 degrees C. (32 degrees F.) at a pressure of 760 millimeters (29.9 inches of mercury, or atmospheric pressure), not including the latent heat of the water of condensation. The following table gives the average volumetric composition of illuminating gas in various cities:
| Cities. | |||||
| London. | Manchester. | New York. | Paris. | Berlin. | |
| Hydrogen | 48 | 46 | 40 | 52 | 50 |
| Carbon monoxide | 4 | 7 | 4 | 6 | 9 |
| Methane | 38 | 35 | 37 | 32 | 33 |
| Various hydrocarbons | 4 | 6 | 7 | 6 | 5 |
| Carbon dioxide | ... | 4 | 3 | ... | 2 |
| Nitrogen | 5 | 2 | 8 | 4 | 1 |
| Oxygen | 1 | ... | 1 | ... | ... |
| 100 | 100 | 100 | 100 | 100 | |
Furthermore, these constituents vary within certain limits. This is also true of the calorific value. Experiments made by the author have demonstrated that in the same place at an interval of a few hours, variations of approximately ten per cent. occur.
Composition of Producer-Gases.—The average chemical composition of producer-gases varies with the conditions under which they are generated and the nature of the fuel. The following are the proportions of its constituents expressed volumetrically: