PETROLEUM 



Properties and Uses 



MINEEAL OIL 



Grade Oil as 

 Fuel. 



Gas. 



Kerosene. 



Benzene. 



Paraffin. 



Purification. 



Kecrystallisation, 



Legisla- 

 tion. 



Flashing-point. 



Apparatus Used. 



Crude petroleum is used to a very slight extent otherwise than as a 

 fuel, a mixture for insecticides and for coarse lubrication. A quantity is 

 also used in gas-making. For other purposes it must be refined, and this 

 is effected by distillation. The crude oil is made up of a number of pro- 

 ducts of different boiling-points, some gaseous, some liquid, some solid. 

 On boiling the oil and condensing the vapours, first the gaseous, then the 

 liquid, and then the solid pass over, leaving a non- volatile residue. These 

 distillates and the residue are themselves made up of a number of different 

 bodies that may to a certain extent be separated. The most valuable of 

 these is the illuminating oil, known also as KEROSENE, coal oil, burning 

 naphtha and by various other names. The portions of the distillate 

 boiling at lower temperatures than the illuminating oils are also of com- 

 mercial value. They are known as gasolenes, rhigolenes, ligroines, ben- 

 zenes, petroleum spirits, etc. Their principal use is as solvents for fats, 

 oils, varnishes, paints, and as fuel for gas engines, gas machines, ice- 

 making machines, and other purposes. The higher boiling portions of the 

 distillate are employed chiefly as lubricants. Still higher boiling portions 

 that condense to solids and semi-solids are known as vaselines and 

 paraffins. 



Simple distillation is not sufficient to prepare the above substances, 

 so that they can be satisfactorily used. They must be purified. This 

 usually consists in distilling, washing with acid (mostly sulphuric), alkali 

 (usually soda or ammonia),' and water. Sometimes the distillates are 

 sprayed through air to remove malodorous constituents. Some of the 

 oils are bleached either by the sun or by chemical reagents, or they may 

 be filtered through charcoal or bone-black. In the case of solids, re- 

 crystallisation is ordinarily resorted to, i.e. the body, such as paraffin, is 

 dissolved in some of the low-boiling constituents, usually naphtha, and 

 the solution cooled in ice and salt. The paraffin thus crystallises out. 



[Anal, of Petrol., in Rec. Oeol. Surv. 2nd., 1891, xxiv. pt. 4, 251 ; Engler, Ohem. 

 Qual. of Petrol, from Burma, 1 894, xxvii., pt. 2, 49-54 ; Hurst. Soav Making, 

 1898, 56-7 ; Thorpe, Diet. Appl. Chem., 1900, iii., 111-20.;, 



Tests and Legislative Measures. The term " Flashing-point " is 

 technically employed to designate the temperature at which any sample 

 of petroleum or its products begins to give off sensible quantities of in- 

 flammable vapour. To prevent accidents it was enacted by the American 

 Petroleum Act, and by the British Petroleum Act of 1871, that no petroleum 

 oil should be used for burning in lamps which gave off inflammable vapours 

 at any temperature below 100 F. (38 C.) when tested in an open cup 

 described in the schedule of the Act. The increase in the consumption of 

 the article, however, between 1871 and 1877 necessitated the adoption of 

 a system of testing less liable to vary. The question was referred to the 

 late Prof. Sir F. Abel, who proposed the use of a closed vessel to be 

 heated in hot water, with a standard flashing-point of 73 F., equivalent to 

 100 on the open-cup system. This proposal was eventually adopted as 

 the basis of the English Petroleum Act of 1879. The law under which 

 petroleum is tested in India is Act XII. (1886), in which the testing 

 apparatus prescribed is an improved form of Abel's. Several other modifi- 

 cations, based on the special conditions attendant on the application of the 

 test in a warm climate, have also been incorporated in the schedule of the 

 Act. As changes of pressure influence the flash-point, a table showing the 

 corrections to be applied for variations in barometric pressure is also 



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