WATER GAS 737
When used for the purpose of enriching a coal gas of low quality, carburetted water gas appears to possess the property of enhancing the illuminating power of the mixture to a greater extent tlian is shown by theoretical reckoning. For in-stance, if 75 per cent, of the mixture consists of coal gas of 13 candles and 25 per cent, is made up from water gas of 18 candles, the final candle-power obtained should, by computation, be 14-25. In practice, however, the actual candle-power of the mixture will be in the neighbourliood of 15 candles, thus showing the additional enriching effect obtained. The explanation, no doubl, is one of flame temperature, water gas buming with a smaller flame than coal gas ; and, when admixed with the latter, the carbon particles of the coal gas are raised to a higher degree of lumiiiosity than when the coal gas is burned by itself.
The impurities in water gas consist of sulphuretted hydrogen and carbon disul-phide. The gas is generally free from ammonia, but occasional traces of this may be found. The proportions in which the impurities are present are approximately as follows :—•
Sulphuretted hydrogen . . . . . 110 to 120 grains per 100 cubic feet, or
about 0-2 per cent, by volume.
Carbon disulphide and other sulphur compounds . 10 to 15 grains per 100 cubic feet.
Recently, there has beeil some question as to the presence of sulphur dioxide in “blue” water gas, but little definite knowledge of its existenceis as yet available. That it should be present, in quantities greater than a small trace is unlikely owing to the fact that it is soluble in water and should, therefore, be readily absorbed in the scrubbers. In purified “ blue ” gas the author has not succeeded in tracing sulphur dioxide.
The specific gravity of water gas is higher than that of coal gas, the gravity of the carburetted gas being in the neighbourliood of 0-65 as against an. average figure of 0-47 for coal gas.
The männer in which the specific gravity of water gas increases with the car dle-power is shown by the following results obtained by F. H. Shelton:—
Candle-Powbk.
19-5.
20-0
22-5
24-0
25-4
26-3
28-3
29-6
30 to 31-9
Specific Gkavity (Air = 1).
0-571
0-630
0-589
0-60 to 0-67
0-64:
0-602
0-70
0-65
0-65 to 0-71
3 B