482 THE POPULAR SCIENCE MONTHLY. 



yield varied from 13,440 to 16,016 cubic feet of 36.08 to 54.45 candle- 

 power gas per ton (6 to 7.15 feet per pound). Experiments on cannel 

 of different kinds have given various yields, from 3.8 feet of 20.52 

 candle-power gas per pound to 4.74 feet of 30.40 candle-power. 



The principal impurities in coal-gas are, as already indicated, sul- 

 phuretted hydrogen and other gases containing sulphur and ammonia. 

 The presence of a small amount of these cannot be avoided, and is 

 not injurious, since the sum of the products of the combustion of these 

 substances, formed by the burning of the gas from a single burner 

 during an entire evening, is very small. In fact, the presence of a 

 slight amount of ammonia is beneficial, in tending to neutralize the 

 sulphurous and sulphuric acids formed by that portion of the sulphur 

 which cannot be renewed. The limit prescribed by law for the Lon- 

 don companies is 20 grains of sulphur and 2f grains of ammonia per 

 100 cubic feet. The specific gravity of illuminating gas is an impor- 

 tant quality, since it increases in a nearly constant ratio with the can- 

 dle-power, so that, knowing the one, the other can be told pretty near- 

 ly, and vice versa. It varies usually from 0.400 to 0.500; the specific 

 gravity of air, 1.000, being taken for the unit. The denser the gas the 

 more slowly it will pass through a given orifice, and so on this quality 

 depends in great measure the quantity which passes through the con- 

 sumer's meter and burner. 



In regard to petroleum as a gas-making material experiments made 

 by Prof. A. Wagner show that naphtha is better and more economi- 

 cal than it or any of the heavy oils. Fifty kilogrammes of petroleum 

 produced 1,547 cubic feet of gas, while the same amount of naphtha 

 produced 1,619 cubic feet. Both petroleum and naphtha produce a 

 large amount of acetylene, a gas which contains a large proportion of 

 carbon. In the experiments referred to, five per cent, of acetylene was 

 evolved, 35.96 per cent, of other heavy (rich) hydrocarbons, and 59 

 per cent, of light (poor) hydrocarbon gas ; the petroleum being split 

 up, with deposition of carbon, into a mixture of acetylene, heavy and 

 light hydrocarbon gas, and hydrogen. In this country, where petro- 

 leum and its products are much cheaper than they are in Europe, it 

 has been found that on a large scale 60 to 80 cubic feet of 50 to 70 

 candle-power gas can be made from one gallon. In a series of thirteen 

 experiments on crude petroleum made by Mr. C. D. Lamson, of the 

 Boston Gaslight Company, the average yield per gallon was 72.71 

 cubic feet, and the average of six tests of candle-power was 45.73. In 

 seven experiments on naphtha the average yield was 79 cubic feet, 

 candle-power 53.48. This is equivalent to a yield per barrel respective- 

 ly of 3,053.82 and 3,338.58 cubic feet. According to Mr. J. ~D. Patton, 

 about 70 cubic feet of 80 candle gas, or 80 feet of 70 candle gas to 

 the gallon, is the maximum yield of petroleum or naphtha. A much 

 smaller burner than the ordinary must be used for gas obtained from 

 pure Albertite, petroleum, or naphtha ; otherwise the flame will smoke, 



