SHALES AND MINERAL OILS 



possible to the gas-jot. A modified carburetter has been successfully employed close 

 to the burner on the Edinburgh street lamps. 



2. The conversion of oil into a permanent gas long baffled inventors. The fact, too, 

 that when oil was so decomposed it usually deposited much of its carbon as coke on 

 the sides^f the retort, was a standing difficulty. Many modifications of water-gas, 

 to be introduced so as again to take up this carbon, and also to supply cheaply an 

 additional volume of gas, were usually proposed. The patent records contain many 

 fruitless schemes ; but Messrs. Keats and Odling report that by Dr. Eveleigh's 

 process, worked out by the Patent Gas Company, a permanent gas has been formed 

 singularly free from impurities, and of 25-candle lighting power. The present 

 position of gaswork economics do not, according to these gentlemen, warrant the hope 

 that the process will be extensively used in large cities, but it may be available in 

 the country and abroad. 



The rising value of cannel coals has induced gas-makers to- inquire whether mineral 

 oils might be used as sources of auxiliary supply in ordinary gas retorts, whether 

 admitted per se, or made into a patent-fuel composition. Mr. Cussiter, of Dalkeith, 

 when introducing oil alone into a retort, obtained in one experiment 15,904 cubic feet, 

 and in another 18,600 cubic feet, with respective illuminating powers of 38'5 and 

 23'55 candles. The illuminating power in another experiment was only 12 candles, 

 but the yield increased to 28,300 cubic feet. When 30 gallons or 284 Ibs. of oil 

 were mixed with splint coal in a clay retort, the yield was increased from 10,000 to 

 12,500 cubic feet, and the illuminating power from 14 candles te 25'89 candles. 

 When 42 gallons of oil were used with 1 ton of coal, 13,140 cubic feet of 28'59-candle 

 gas were obtained. 



As we have already seen, shale is very widely distributed throughout the geological 

 formations ; and shale, which is useless for oil-making from poorness of yield and 

 probable organic origin, may be used for gas-making. Specially should the gaswork 

 be planted where the shale is mined, and the manufacture led in by pipes to the town 

 where it is to be used. During the winter of 1872 many Scotch gas companies used 

 ordinary oil-shale brought into their works from a distance. 



Paraffin and pstroleum residues have been utilised in small gasworks supplying 

 railway-stations or private residences in Germany. The stuff is pumped up by 

 clock-work into a retort capable of making 200 cubic feet of gas in an hour, which 

 contains only 0-69 per cent, of impurities in the hundred parts. The gas consists 

 chiefly of acetylene ; and it is burned from jets consuming per hour from a of 

 a cubic foot to 2 cubic feet ; but 200 cubic feet of this gas equal 1,000 cubic feet of 

 coal-gas. Convenience rather than cost of material instigates the erection of such 

 works. 



Petroleum has been successfully employed in small towns and villages of Canada 

 and the United States for gas-making. The method usually adopted is to mix its 

 vapours with that of water passing over red-hot charcoal or iron. Youle, Hind, and 

 Thomson found 10 cubic meters of the gas equal in intensity and cheapness to 40 

 cubic meters of coal-gas. Besides, the manufacture consumes much less time. See 

 NAPHTHA. 



Mineral oils as liquid fuel. The proposal to use such oils for raising steam excited 

 great interest when first proposed. Many contrivances were patented and experiments 

 undertaken, though without the happy issue anticipated. The following resume of 

 our knowledge on this subject is mainly derived from the evidence of Dr. B. Paul 

 given before the Royal Commission on Coal Supply. 



The materials which have been suggested as fuel are : Petroleum in a crude state, 

 with a specific gravity from 800 to 860 ; crude paraffin oil of sp. gr. 860 to 900 ; 

 heavy oils, the waste products from the distillery known as ' bottoms,' ' foots,' &c. ; 

 dead oil, or creasote of coal-tar distiller, sp. gr. 1050. All these substances are much 

 more highly inflammable than coal. Crude petroleum and paraffin-oil stand at tho 

 top of the list in this respect ; dead oil at the foot. 



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