OIL 



are now hundreds of depots at 

 which various petroleum products 

 are stored in bulk, and which serve 

 as distributing centres to the 

 adjacent localities. 



In the 20th century the world's 

 production of petroleum increased 

 very largely, owing to the open- 

 ing up of new oilfields. It is 

 now more than 100,000,000 tons 

 per annum, of which the U.S.A. 

 produces about 65,000,000 tons, 

 Mexico about 25,000,000 tons, and 

 the British Empire less than 

 2,000,000 tons, principally from 

 Burma, Egypt, and Trinidad. 

 Russia produces about 4,500,000 

 tons, the Dutch East Indies over 

 2,000,000 tons, Rumania 1,200,000 

 tons, and Persia, where the oilfields 

 are under British control, about 

 1,000,000 tons. As the Empire con- 

 sumes about three times as much 

 oil as is produced within its bor- 

 ders, recent discoveries of oil in 

 the N.W. of Canada and elsewhere 

 are of considerable importance. 



OIL IN GREAT BRITAIN. In Octo- 

 ber, 1918, the first well drilled in 

 Great Britain for oil was started at 

 Hardstoft in Derbyshire, and at 

 the end of the following May it 

 began to produce oil at the rate of 

 about 1 ton per day. About a 

 dozen other wells have been drilled, 

 but none has found oil in appre- 

 ciable quantities. The best scien- 

 tific opinion, however, inclines to 

 the belief that oilfields of moderate 

 yield are possible in Great Britain. 

 By the Petroleum (Production) Act, 

 1918, the crown alone has the right 

 to drill for oil in Great Britain ; 

 but it may license other parties 

 to drill ; and three or four such 

 licences have been issued. 

 Uses of Oil 



Without petrol, motor and aero- 

 plane traffic would be practically 

 impossible, for even though sub- 

 stitute fuels might be used for these 

 purposes their quantity is com- 

 paratively insignificant. Paraffin 

 oil is still the world's chief illu- 

 minant where gas and electricity are 

 not available. For modern mach- 

 inery the lubricating oils obtained 

 from petroleum are essential, alone 

 or with an admixture of vegetable 

 oil. Oil fuel is being used to a 

 greater extent every year, and is 

 employed by the largest and most 

 modern British liners. The navy 

 now uses it almost exclusively. Its 

 use on British railway engines in 

 place of coal has begun ; and many 

 electric power plants burn the 

 liquid fuel. From some crude oils 

 an oil fuel can be obtained suitable 

 for use in the internal combustion 

 engine, or " oil engine," which is 

 proving an economical source of 

 power without the necessity for 

 raising steam. The household candle 



5830 



of to-day is usually made of paraffin 

 wax ; vaseline is much used in 

 medicine ; and there is a large 

 demand for petroleum asphalt 

 for road-making, roofing, and other 

 purposes. 



OILS AND FATS. The oils present 

 in animal and vegetable organisms 

 form a homogeneous group, those 

 which are solid above 68 F. being 

 called fats, the remainder being 

 liquid fats or oils. They are 

 neutral bodies with an unctuous 

 feel and, when pure, are tasteless 

 and odourless. Practically in- 

 soluble in water and except 

 castor oil in cold alcohol, they 

 dissolve in ether, benzene, and in 

 one another. They leave on paper 

 grease-spots which are irremovable 

 by evaporation. All lighter than 

 water, their specific gravity ranges 

 from 0-913 in rape oil to 0'975 in 

 so-called Japan wax. 



Varieties of Oils 



These fatty or fixed oils differ 

 from essential oils and volatile 

 mineral oils in not being volatile 

 without decomposition. Composed 

 of carbon, hydrogen, and oxygen, 

 they are mixtures of two or more 

 triglycerides, which are compounds 

 of the alcohol glycerin with two or 

 three of the fatty acids. Of these 

 the commonest are the liquid 

 oleic and the solid palmitic and 

 stearic acids, which in combination 

 with glycerin form water and the 

 triglycerides triolein, tripalmitin, 

 and tristearin respectively. True 

 waxes including sperm oil differ 

 from them in containing alcohols 

 other than glycerin. Above 572 F. 

 all are decomposed, the glycerin 

 being broken up into water vapour 

 and acrolein, which causes the 

 penetrating odour of burning oil. 



When treated with superheated 

 steam they are hydrolysed or 

 broken up into their glycerin and 

 fatty acid constituents. When 

 they are boiled in caustic alkalis 

 this hydrolysis is called saponifi- 

 cation, the fatty acids being con- 

 verted into soaps. In airtight 

 vessels oils and fats keep in- 

 definitely, but in the presence of 

 water and natural enzymes hydro- 

 lysis sets in, free fatty acids are 

 released, become oxidised on 

 exposure to air and light, and give 

 rise to the condition described as 

 rancid. " 



Fixed oils and fats are essential 

 for human food, are of great 

 importance as medicines and 

 unguents, and furnish raw mater- 

 ials for soaps, candles, burning 

 oils, lubricants, paints, varnishes, 

 leather-dressing, linoleum manu- 

 facture, and the like. On exposure to 

 air some become oxidised and form 

 an elastic skin. This property is 

 utilised in their classification, thus : 



OIL 



(1) Vegetable : Oils drying (lin- 

 seed) ; semi-drying (cotton-seed, 

 colza) ; non-drying (almond, olive, 

 castor). Fats palm, cacao, coco- 

 nut, ghee butter. 



(2) Animal : Oils marine (fish, 

 liver, blubber) ; terrestrial (neat's- 

 foot). Fats drying (rattlesnake) ; 

 semi-drying (rabbit, horse) ; non- 

 drying (lard, tallow, butter). 



(3) Drying oils usually contain 

 trilinolenin, and semi-drying oils 

 trilinolin ; linseed oil has 71 p.c. 

 of the one and 13 p.c. of the other. 



Methods of Extraction 



The proportion of oil in seeds 

 and fruits ranges from 85 p.c. in 

 white mustard to 18 p.c. in soya 

 bean. Apart from primitive 

 manual processes, extraction is 

 effected in three ways. Rendering, 

 chiefly applied to animal fats, 

 consists in heating the sodden 

 material, with or without an acid, 

 in open kettles or closed autoclaves. 

 Pressure is chiefly applied to oil- 

 seeds and nuts, which are pre- 

 pared by decorticating, crushing, 

 grinding, and moulding, the meal 

 being then subjected to hydraulic 

 pressure between open plates or 

 in closed cylindrical cage-presses. 

 Cold-pressed or cold-drawn oils are 

 pale, and furnish the salad and 

 virgin oils of commerce. Hot- 

 pressing may follow, and the 

 residual meal-cake, still retaining 

 7-10 p.c. of oil, makes cattle-food. 



The highest possible oil-yield is 

 attained by employing hot or 

 cold solvents, chiefly carbon di- 

 sulphide or tetrachloride, petro- 

 leum ether, and benzene. The 

 residual cake may have only 1 p.c. 

 of oil. Further processes include 

 filtering, refining, bleaching, and 

 deodorising. 



Tallows and lard are rich in 

 tristearin, palm oil in tripalmitin, 

 olive oil in triolein. Oleic acid, 

 present in most oils, differs from 

 stearic acid only in containing 

 two atoms less of hydrogen. As 

 the glycerides of the fats are needed 

 more and more for foodstuffs and 

 cannot be spared for other purposes 

 means have been devised for hydro - 

 genating or hardening oils into 

 fats. A favourite method of effect- 

 ing this is to treat triolein with 

 powdered nickel in the presence of 

 hydrogen, which transmutes it into 

 tristearin. Cotton-seed and whalfe 

 oil are thus converted into frying 

 fats and materials for margarine, 

 and these synthetic fats serve to 

 supplement the supply of natural 

 tallows for soap and candles. < 



In 1919 the United Kingdom 

 imported nuts, kernels, and seeds 

 to the value of 55,536,000 ; 

 vegetable oils, 21,800,000 ; animal 

 oils, oleomargarine, and tallow, 

 18,360,000 ; oil-cake, 5,821,000 ; 



