PARAFFIN 509 



chambers. The bowl or kiln is charged with the cannel or shale, on the top of 

 which is laid a stratum of burning coke or a mixture of coke and slack. As soon 

 as this upper stratum is in a state of full combustion, the exhaustion is commenced 

 by means of a steam-jet, and the heated products of combustion are drawn down 

 through the charge. That portion immediately below the fire is of course the first 

 acted upon, the action commencing with a distillation of the most volatile products. 

 As the heat increases, the more stubborn and denser vapours are driven downwards 

 through the lower mass, and by their heat commence the distillation there. Sub- 

 sequently, the upper layer of cannel having all its volatile constituents driven off; 

 becomes a coke, and at this stage is so highly heated as to burn and give off com-- 

 bustion products, viz. carbonic oxide, &c., instead of distillation products, thus serving 

 as fuel for the cannel below, and so on till the mass is coked to the bottom. When 

 this is completed, the steam-jet is turned off, the exhaustion ceases, and the charge is 

 drawn from below, a portion of it being used in its burning state for starting a 

 neighbouring kiln, which should always be charged ready to commence working when 

 its predecessor has reached this stage. 



The size of Mr. Holmes' meerschaums is 12 feet high, and 8 feet diameter, internal 

 measurement. They are to be charged to a depth of 10 feet, and to contain 12 tons 

 of cannel. 



Mr. Holmes' attempt to introduce this retort in Wales proved disastrous. In 1866, 

 Me Beth patented an adaptation of the principle to the ordinary Scotch retort [Spec. 

 A.D. 1866, No. 2788]. Very poor shales were worked to profit ; but the skill necessary 

 to produce a good product in the daily working proved a serious drawback. Ordinary 

 labour only is requisite for the common retorts. Messrs. Young and Stephens have 

 patented a new retort similar to one already described, but doing without the aid of 

 coal. Suppose four retorts, similar in section to fig. 1605, built in a bench, but the 

 bottom of each open, and having attached to each a condensing apparatus, at the 

 extremity of which is a steam-jet. Each cylinder receives a charge of shale which is 

 renewed every 5 hours ; a fire of coals is then lighted in the furnace, which begins 

 distillation, at the same time igniting the lower layer of shale : a portion of this falls 

 out into the space betwixt the furnace-wall and the retort and acts instead of coal. 

 The condensers being now filled with vapours, the steam-jet is set in motion, and air 

 is exhausted from the retort, the condensible vapours become crude-oil, and the incon- 

 densible gas is returned to play on the walls of the shale cylinders. The oil is of 

 good specific gravity unburnt, very rich in paraffin, and equal in yield to the ordinary 

 retorts. No coal is necessary, except when the distillation begins either at the com- 

 mencement of the works or after a shut-down. Other inventors are busy on the pro- 

 blem, in making the material giving the valuable paraffin yield power for its extrac- 

 tion. On this solution mainly rests the possibility of our shale-oil manufacturers 

 competing successfully with the petroleum from the American springs ; and also of a 

 more extended use of solid paraffin for many new processes in the arts. For the pro- 

 duction of solid paraffin, a bye-product in mineral-oils when burning-oil brought Is. 6d. 

 to 3s. 6d. per gallon, is now a main source of income, when the former main product 

 only brings Is. per gallon or less nett at the works. 



Boghead and the cannels usually yield from 1 to 1*4 per cent, of paraffin scales of 

 raw materials used ; Scotch shales, in ordinary manufacture, 3 to 4 per cent. But 

 individual shales are known yielding a very large percentage of this substance, which, 

 unlike the burning-oils, increases in commercial value. When bodies are worked for 

 this alone, much of the expense of an oil-refinery will be saved ; and the resulting 

 oils in their manufacture may be sold almost at the price of waste substances. 



Paraffin refiners receive supplies of their raw material from other natural sources. 

 Peat-tar often contains a large percentage, but the resulting paraffin is very soft. 

 Ozokerite and neft-oil, derived from the Caspian Sea and Hungary, now command 

 high prices as sources of paraffin scales. Neft-oil is said to give 68 per cent, of dis- 

 tillate, consisting of 60 per cent, of crude paraffin and 8 per cent, of oil. The- 

 Galician ozokerite gives by distillation some 24 per cent, of paraffin, and 45 per cent, 

 of oil. 



The refining of the liquid portion of the crude oils is still conducted in the manner 

 described. (See SHAI/E and MINERAL OILS.) A great many patents have been secured, 

 a large proportion of them evidently based upon the theory that the refining of these 

 oils is simply a process of oxidation analogous to that of the bleaching of vegetable 

 colours. Some degree of oxidation undoubtedly does take place in the course of the 

 refining process, but this is far from being the whole action. The sulphuric acid 

 appears to act chiefly as a carbonising agent, and by heterogeneous adhesion to the 

 carbonaceous or pitchy colouring-matters which it carries down with it in the form of 

 ' acid-tar.' The theory of the action is, however, by no means fully understood. It 

 still offers a most interesting field for a thorough investigation. 



