550 GAS, COAL 



have as yet seen no reason for giving our preference in favour of any one of these 

 diluents ; if, however, we study their behaviour during combustion, wo shall find that 

 where the gas is to be used for illuminating purposes, hydrogen has qualities which 

 give it a very decided preference over the other two. When gas is used for lighting 

 the interior of public buildings and private houses, it is very desirable that it should 

 deteriorate the air as little as possible, or, in other words, it should consume as small 

 a quantity of oxygen and generate as little carbonic acid as possible. The oppressive 

 hoat which is so frequently felt in apartments lighted with gas also shows the advan- 

 tage of the gas generating a minimum amount of heat. 



The following is a comparison of the properties of the throe non-illuminating gases 

 in reference to the points just mentioned : 



One cubic foot of light carburetted hydrogen, at 60 Fahr. and 30 inches baro- 

 metrical pressure, consumes 2 cubic feet of oxygen during its combustion, and 

 generates 1 cubic foot of carbonic acid, yielding a quantity of heat capable of heating 

 5 Ibs. 14 oz. of water from 32 to 212, or causing a rise of temperature from 60 to 

 30 0- 8 in a room containing 2,500 cubic feet of air. 



One cubic foot of carbonic oxide, at the same temperature and pressure, consumes, 

 during combustion, \ a cubic foot of oxygen, generates 1 cubic foot of carbonic acid, 

 and affords heat capable of raising the temperature of 1 Ib. 14 oz. of water from 32 

 to 212, or that of 2,500 cubic feet of air from 60 to 66 0f 6. 



One cubic foot of hydrogen, at the same temperature and pressure, consumes \ a 

 cubic foot of oxygen, generates no carbonic acid, and yields heat capable of raising 

 the temperature of 1 Ib. 13 oz. of water from 32 to 212, or that of 2,500 cubic feet 

 of air from 60 to 66'4. 



This comparison shows that light carburetted hydrogen is very objectionable as a 

 diluent, not only on account of the carbonic acid which it generates, but also by reason 

 of the very large quantity of oxygen which it consumes, and the very great amount 

 of heat which, in relation to its volume, it evolves on combustion ; the consumption of 

 oxygon being four times, and the absolute thermal effect more than three times as 

 great as that of either of the other gases. 



The quantity of heat evolved by the combustion of equal volumes of carbonic oxide 

 and hydrogen is nearly, and the amount of oxygen consumed quite, the same ; but 

 the carbonic acid evolved from the first gives a decided preference to hydrogen as the 

 best diluent. 



The same comparison also shows that when the gas is to be used for heating pur- 

 poses, and the products of combustion are carried away, light carburetted hydrogen 

 is by far the best diluent. 



The experiments of Dulong on the absolute thermal effects of hydrogen, light 

 carburetted hydrogen, and carbonic oxide are taken as the basis of the foregoing cal- 

 culations. Dulong found that 



1 Ib. of hydrogen raised the temperature of 1 Ib. of water through 62,471 F. 

 1 Ib. of carbonic oxide 4,505 F. 



1 Ib. of light carburetted hydrogen 24,244 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 illuminating compounds from 

 a given weight of material. 



2nd. The formation of a due proportion of illuminating and non-illuminating con- 

 stituents, 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 obtain 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 carburettod 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. 



For some time previous to the strike of the gas-stokers, and to the temporarily- 

 diminished illumination which it produced, a number of ingenious persons wore 

 busy with endeavours to improve and cheapen the manufacture of gas ; and the 

 strike had tho good effect of attracting to their labours more attention than those 

 would otherwise have commanded. About that time two now methods were 

 brought prominently before tho public one of them being the process of Messrs. 

 Porter and Lane, the property of the Gas Generator Company, and the other being 

 tho process of Mr. Ruck, which is now vested in the New Gas Company. See GAS, 

 WATKR. 



The method of Messrs. Porter and Lane consists essentially in an improved arrange- 



