78 



CONTRIBUTIONS TO THE KNOWLEDGE 



of hydrogen, light carburetted hydrogen, and carbonic oxide, 

 are taken as the basis of the foregoing calculations. Dulong 

 found that — 



1 lb. H raised the temperature of 1 lb. HO through 62471°F. 

 1 lb. CO " " 1 lb. " 4504°F. 



1 lb. CHj « «' 1 lb. " 24244°F. 



These considerations indicate the objects that should 

 chiefly be regarded, in the generating department of the 

 manufacture of gas for illuminating purposes. They are — 



1st. The extraction of the largest possible amount of illu- 

 minating compounds from a given weight of material. 



2nd. The formation of a due proportion of illuminating 

 and non-illuminating constituents, so that on the one hand 

 the combustion of the gas shall be perfect, and without the 

 production of smoke or unpleasant odour, and on the other the 

 volume of gas required to procure a certain amount of light 

 shall not be too large. 



3rd. The presence of the largest possible proportion of 

 hydrogen amongst the non-illuminating constituents, to the 

 exclusion of light carburetted hydrogen and carbonic oxide, 

 so as to produce the least amount of heat and atmospheric 

 deterioration in the apartments in which the gas is consumed. 



I have not introduced these preliminary remarks to show 

 the inductive reasoning by which the process of gas-making 

 described below was arrived at, for I believe that, so far as 

 the above considerations are concerned, that process was 

 accidentally adopted ; but I bring them forward to illustrate 

 and explain the results of the following experiments, and 

 also to show that a close study of the chemistry of gas- 

 manufacture would have led to the discovery of this more 

 philosophical method of gas-generation long ago. 



Mr. White's process consists essentially in the generation 

 of non-illuminating combustible gases by the action of steam 

 upon charcoal, coke, or other deoxidizing substances, in a 



