PARAFFIN 



749 



in consequence a time of much prosperity, ending, 

 however, in a partial collapse by reason of over- 

 production in Scotland combined with ever-increas- 

 ing imports of wax from America. The sixth 

 period, for a few years from 1887, was a period of 

 combination, the Scotch and American producers 

 haying combined to restrict the supplies of paraffin- 

 wax. After 1894 the Scotch companies suffered again 

 from American (and also Russian) competition. 



Geologically, the position of the shale in the east 

 of Scotland is in the Lower Carboniferous series, 

 but in the west of Scotland it is found in the 

 ordinary coal-measures. There are some seven or 

 eight different seams of shale, all varying in position 

 and quality from each other ; but the same shale 

 also varies from its normal character in different 



districts, being thick and rich in one place, and 

 thin and poor in another. The Broxburn seam of 

 shale at its best is probably the richest ami most 

 profitable quality to work ; but the Pumpherston 

 seams of shale, though poor in oil, have now be- 

 come of value, because they are rich in ammonia. 

 The shale is procured in the same manner as in 

 coal-mining. 



The following summaries will indicate the 

 material facts in the history of the trade in Scot- 

 land, and the direction and! extent to which the 

 improved processes have tended viz. diminished 

 yield of burning oils, increased yield of lubricating 

 oils, paraffin-wax, and sulphate of ammonia, to- 

 gether with reduction of loss in process of manu- 

 facture. 



SUMMARY NO. 1. 



End at 3d Period 1872. End of 4th Period 187i 



Number of works and capital employed 61 1,760,000 18 1,400,000 



Output of shale 800,000 860 000 



Crude oil produced 26,000,000 29.000,000 



Burning oils produced 11,280,000 11,400,000 



Lubricating oils produced 2,500,000 6,000.000 



Paraffin-wax produced 5,800 9,200 



Sulphate of ammonia 2,350 4,750 



1890. 

 IS 2,000,000 



1,869.300 tons. 

 62,876,700 gallons. 

 21,680,000 

 9,000,000 ,, 

 22,846 tons. 

 18,483 .1 



SUMMARY NO. 2. 



SHOWDfO PERCENTAGE OF PRODUCTS UNDER THE OLD AND NEW SYSTEMS OP WORKING. 



Naphtha. 



Old System (1880) parts per 100 5 



New System (1890) 4 



The first most notable improvement was the 

 Henderson retort, patented by N. M. Henderson in 

 1873. With this retort the spent shale off which 

 the oil had been distilled, and which still con- 

 tained alxrat 12 per cent, of carbon, was allowed to 

 descend into the furnace beneath the retort to serve 

 as fuel in the distillation of fresh charges of shale. 

 This effected a great saving of coal and labour, and, 

 on account of mild temperature produced with 

 regularity, there was increased yield of products of 

 better quality and more easily refined. 



In 1882 Mr William Young and Mr George 

 T. Beilby, combining the results of their experi- 

 ments, patented a new retort. It is a combina- 

 tion of two retorts ; in the upper one the ordinary 

 oil-products are distilled oft, after which the 

 shale is allowed to fall into a firebrick retort 

 below, where a higher heat is employed and in 

 which it is exposed to a current of steam and air ; 

 this method gives a greatly increased yield of 

 ammonia ; and it is therefore a form of retort of 

 the utmost value in the case of shales rich in nitro- 

 genous and poor in bituminous products. 



This was followed in 1883 by Mr Henderson's 

 continuous distillation process, in which the crude 

 oil passes by gravitation through three stills. 

 During the progress of the oil through these stills 

 the f ract ionatii in or separation of the crude oil into 

 naphtha, burning oil, and heavy or lubricating 

 oil containing paraffin takes place automatically. 

 In addition to these three stills there are two or 

 more coking stills into which alternately the 

 residue of the crude oil flows and where the dis- 

 tillation is completed, the dry coke being removed 

 from each at regular intervals. The advantages 

 obtained from tins process are saving in first cost 

 of plant, saving of labour, time, and fuel ; less cost 

 of maintenance ; the fractionation of the oil is 

 more perfect and uniform, and the distillates purer, 

 giving less loss in refining. Mr Henderson also, 

 by a patented process, greatly simplified and 

 cheapened the cost of the production of sulphate of 

 ammonia. And his new methods of refrigeration 

 and refinement of the erode paraffin scale increased 

 the yield of wax and improved the quality of the 

 lubricating oils. 



Burning 

 Oils. 

 40 

 36 



Lubricating 

 Oils. 

 13 



ir 



8 

 14 



Lou In 

 process. 



84 



80 



In the distillation of bituminous minerals for the 

 production of gas a bright-red heat is employed in 

 order to obtain as much incondensable vapour or 

 permanent gas as possible. The aim of the oil- 

 manufacturer on the contrary is to minimise the 

 production of incondensable gas, and to obtain the 

 highest percentage possible of the liquid and solid 

 hydrocarbons. He therefore reduces the distillation 

 temperature to the lowest practicable point viz. 

 from 600 to 800 F. 



Crude oil is composed of a very wide range of 

 hydrocarbons, each varying in specific gravity and 

 boiling-point and in the percentage of carbon 

 present ; but in the practical operations of the 

 refiner the fractionation of the oil is confined within 

 certain definite limits which have been found 

 of most convenience commercially viz. Naphthn, 

 specific gravity, 680 to 750 (water = 1000); volatile 

 at ordinary temperatures ; the highest portions are 

 used for carbnretting air gas ; the heavier portions 

 are principally used as solvents. Burning oils (a) 

 for domestic use ; specific gravity, 800 to 805 ; flash- 

 point, Abel test, about 100 F. (6) Lighthouse oil, 

 specific gravity, 810 to 815 ; flash-point, Abel 

 test, about 150 F. (c) High Test oils, specific 

 gravity, 830 to 840 ; flash-point, Abel test, about 

 240 F. ; used in special lamps for lighting railway- 

 carriages and in ships. Lubricating ous: These 

 are made of various standard specific gravities viz. 

 865, 875, 885, 890-5. They are used principally 

 for mixing with animal and vegetable oils in the 

 preparation of lubricants. Paraffin-wax, with 

 mefting-points varying from 80 to 130 F. The 

 soft wax from 80 to 100 is employed instead of 

 sulphur in the preparation of ordinary safety- 

 matches, while the harder qualities are manu- 

 factured into candles. 



The operations in the production and refine- 

 ment of mineral-oil products stated briefly are : 

 The shale when taken from the pits is broken 

 into small pieces and put into the retorts. In the 

 retort the first chemical process, destructive dis- 

 tillation, takes place. The various products of the 

 oil- works do not exist as such in the shale; .hey 

 are all created by its destructive distillation. The 

 shale, according to quality, yields from 20 to 40 



