SHALES AND MINERAL OILS 767 



of fixed carbon; its sole residuum is a useless mass of clay. The superior character 

 of the American petroleum, as well as the high prices ruling for gas material, have 

 caused cannels, lignite, peat, as well as many caking coals, to be disregarded as oil- 

 producing materials. At the same time, the technologist should note the physical and 

 chemical capabilities of such, bodies for producing oils for other than domestic uses. 

 Dr. Eveleigh has proposed to manufacture gas from oil distilled first from ordinary 

 coal by a special apparatus. Messrs. Odling and Keats, in reporting on this process 

 for the Patent Gas Company, state that in their experiments, silkstone coal gave 16 - 4 

 gallons of tar and oil per ton; Clay cross main, 11*9 gallons ; and Pelaw main, 13-9 

 gallons : or a mean of 14 gallons. They obtained from one ton of coal 9,500 cubic feet 

 of 23-candle gas, and from 14 gallons of oil the produce of this 600 cubic feet of 25- 

 CJindle gas. Though the American oil-wells may be said to have shut up the peat- 

 works of the Continent, lignite is distilled there often specially for the extraction of 

 paraffin. 



A natural transition from petroleum to shale is exhibited, for instance, in the exten- 

 sive gum-beds near Hamilton, Canada West. The viscous asphaltum may be only the 

 fluid native naphtha changed by atmospheric oxidation ; and, at least, some beds of 

 anthracite may be only farther steps in the same series of changes. Attempts to 

 extract their proximate constituents from these bodies by solvents have been as fruit- 

 less as those made on coals. Indeed, the recent experiments of Berthollet appear to 

 show that the various hydrocarbons of coal-tar, and probably those also in crude shale 

 oil, do not exist individually in the materials whence those bodies are extracted, but 

 depend on different temperatures applied in distillation. By synthesis, Berthollet 

 obtained benzine from acetylene ; ethylene from acetylene and hydrogen ; styrolene 

 from ethylene and benzine ; and naphthaline from ethylene and styrolene. Inversely, 

 by the application of a red heat on toluene, xylene, and cumei?e, they were decomposed 

 into hydrogen, formene, acetylene, ethylene, benzine, toluene, xylene, cumene, styrolene, 

 naphthaline, anthracene, and chrysene. The gas-maker notes a strange individuality 

 in the yield of special materials. The Newcastle coal-tar abounds in naphthaline ; 

 the Wigan cannel is specially rich in benzine and carbolic acid. So the oil-maker 

 prefers crude tar from the lower carboniferous shales ; specially, because they give a 

 white odourless burning-oil ; though other crude oils are cheaper, yield more paraffin, 

 or may better suit applications to patent fuel, metallurgy, or gas-making. Probably 

 more accurate knawledge of the different effects of heating in this manufacture may 

 enable the oil-maker to extract equally good tar from any oil-yielding material ; 

 and likewise to obtain in gas-making from shales all the peculiar products of cannel 

 coals. 



Oil-shales, like cannel coals, have a yellow-brownish streak ; are easily cut with a 

 knife ; and often exhibit a subconcho'idal fracture. The ' curley ' bands have a black 

 glossy external appearance ; and are curiously bent into a series of corrugated foldings. 

 They yield most oil ; and are usually mixed with thick seams of poorly oleaginous 

 shales. In some parts of Linlithgowshire, these shales are changed into a kind of black 

 chalk ; apparently in consequence of the trap rocks. 



What are Mineral Oils? To iinderstand mineral oil-making, it is necessary to 

 consult some good table of temperatures, such as Pouillet's. 



The black heat or low-red heat of oil-making ranges betwixt 500 and 900 F., 

 while the full cherry-red or dark -yellow red heats, so necessary in coal-gas manufac- 

 ture, exceed 1000. Shale-tar floats on the surface of water ; whereas, coal-tar being 

 of a higher density, sinks in it. Crude mineral-oil may be as high as 940 in sp. gr ; 

 but the shale-tar preferred for oil-making usually ranges from 840 J sp. gr. to 890 

 sp. gr. 



Crude-oil is really a series of oils held together by links destroyed in distillation. 

 But the separate oils may be variously utilised, in accordance with their several 

 physical and chemical properties. Yet, as they all are hydrocarbons, they cannot take 

 the place of oxygenated oils of animal or vegetable origin used by painters or soap- 

 makers. Mineral turpentine, the only apparent exception, is used by varnish-makers, 

 not from its drying properties, but from its speedily evaporating altogether out of the 

 paint-solution in which it was mixed. 



Mineral oils in lamps. They were first introduced as illuminants along with the 

 now familiar German lamp; and they have largely displaced lamps using other 

 vegetable or animal oils from their greater convenience, and from the superior 

 brilliancy and cheapness of the light given. Olefiant gas mainly is thus given in the 

 remotest hamlet, under circumstances of the easiest management. From the vapori- 

 sable nature of the oil, a lamp is supplied surpassing most previous similar contrivances 

 in photogenic power. Continued application of ingenious minds has reduced the 

 glass nuisance to a minimum, whilst it is now the fault of the purchaser should he 

 employ a dangerous oil, Dr. Frankland gives the following results of experiments of 



