In the illuminants, if we add the higher members of the methane series present to the olefines, we see they are about equal in each gas, while the low percentage of nitrogen in the Lowe gas is due to more careful working, and could easily be attained with the Van Steenbergh plant by allowing the first portion of water gas to wash out the producer gas before the hopper on top is closed. The cracking of the naphtha by the red hot coke is undoubtedly a great advantage, for, as I have pointed out, the cracking of rushing petroleum is an exothermic reaction, so that the coke at the top of the generator gets hotter and hotter, and it is no unusual thing to see the coke at the beginning of the make cherry red at the bottom and dull red at the top, while at the end of the make it is almost black at the bottom and cherry red at the top, in this way attaining the same advantage in working that the Springer and Loomis do by their down blast, that is, having the fuel at its hottest where the gas finally leaves it, so as to reduce the quantity of carbon dioxide, and so lessen the expense of purification. It will be well now to turn for a few moments to the gas obtained by cracking the light petroleum oils by themselves. The Russian and American petroleum differ so widely in composition that it was necessary to see in what way the gases obtained from them differed; and to do this, equal quantities of American naphtha and a Russian naphtha were cracked, by passing through an iron tube filled with coke, and in each case heated to a cherry red heat, the gases being measured, and then analyzed, with the following results: American. Russian. No. of cubic feet per gallon... 72 104 ---- ---- Hydrogen....................... 26.0 45.3 Methane........................ 41.6 22.3 Ethane......................... 12.5 13.9 Olefines....................... 14.1 11.6 Carbon monoxide................ 3.3 3.5 Carbon dioxide................. 1.7 2.3 Oxygen......................... 0.8 1.1 Nitrogen....................... Nil. Nil. ----- ----- 100.0 100.0 Showing that, if the Russian oil is a little lower in illuminants, it quite makes up by extra volume, but it seemed to me to deposit a much larger proportion of carbon. Taking 21/2 gallons of American naphtha, it would give roughly 180 cubic feet of gas of the above composition, while the remaining gas would be the ordinary water gas. Taking the analysis of this as given, and calculating from it what would be the composition of a mixture of it with the naphtha gas, we obtain: