ADDRESS. 19 



and an increased supply of the valuable by-products previously referred 

 to. The quantity of both ammonia and heating gas may be further 

 increased by the simple expedient of passing a streamlet of steam through 

 the heated retorts towards the end of each operation, whereby the 

 ammonia and hydrocarbons still occluded in the heated coke will be 

 evolved, and the volume of heating gas produced be augmented by the 

 products of decomposition of the steam itself. It has been shown that 

 gas may be used advantageously for domestic purposes with judicious 

 management even under present conditions, and it is easy to conceive 

 that its consumption for heating would soon increase, perhaps tenfold, if 

 supplied separately at, say, Is. a thousand cubic feet. At this price gas 

 would be not only the cleanest and most convenient, but also the cheapest 

 form of fuel, and the enormous increase of consumption, the superior 

 quality of the illuminating gas obtained by selection, and the propor- 

 tionate increase of by-products, would amply compensate the gas com- 

 pany or corporation for the comparatively low price of the heating gas. 



The greater efficiency of gas as a fuel results chiefly from the cir- 

 cumstance that a pound of gas yields in combustion 22,000 heat units, 

 or exactly double the heat produced in the combustion of a pound of 

 ordinary coal. This extra heating power is due partly to the freedom 

 of the gas from earthy constituents, but chiefly to the heat imparted to it 

 in efiecting its distillation. Recent experiments with gas-burners have 

 shown that in this direction also there is much room for improvement. 



The amount of light given out by a gas flame depends upon the 

 temperature to which the particles of solid carbon in the flame are raised, 

 and Dr. Tyndall has shown that, of the radiant energy set up in such a 

 flame, only the o^th part is luminous ; the hot products of combustion 

 carry ofi" at least four times as much energy as is radiated, so that not more 

 than one hundredth part of the heat evolved in combustion is converted 

 into light. This proportion could be improved, however, by increasing 

 the temperature of combustion, which maybe effected either by intensified 

 air currents or by regenerative action. Supposing that the heat of the 

 products of combustion could be communicated to metallic surfaces, and 

 be transferred by conduction or otherwise to the atmospheric air sup- 

 porting combustion in the flame, we should be able to increase the tem- 

 perature accumulatively to any point within the limit of dissociation ; 

 this limit may be fixed at about 2,300° C, and cannot be very much 

 below that of the electric arc. At such a temperature the proportion of 

 luminous rays to the total heat produced in combustion would certainly be 

 more than doubled, and the brilliancy of the light would at the same time 

 be greatly increased. Thus improved, gas-lighting may continue its rivalry 

 with electric lighting both as regards economy and brilliancy, and such 

 rivalry must necessarily result in great public advantage. 



In the domestic grate radiant energy of inferior intensity is reqiiired, 

 and I for one do not agree with those who would like to see the open 

 fireplace of this country superseded by the continental stove. The 



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