August 1, 1898.] 



KNOWLEDGE 



169 



Founded in i88i by RICHARD A. PROCTOR. 



LONDON: AUGUST 1, 1898. 



CONTENTS. 



The Petroleum Industry. — III. By Cteobqe T. Hollowat, 

 ASSOC. K.c.s. (lo^d.), f.i.c. {Illustrated) 



AnOld-World Highland. By GuE>-yiLLB A. J. Colb, ji.e.i.a., 

 F.G.S. {Illustrated) ..." 



Self-Irrigation in Plants. — II. By the Eev. Albx. S. 

 Wilson, m.a., b.sc. {Illustrated) ... ... 



Celebes: a Problem in Distribution. By R. Ltdekkeb, 



B.A., P.B 3 



British Ornithological Notes. Conducted by Habby F. 



WlTHBEBY, F.Z.S., JI.B.O.r 



'• Insect Miners." Bv Feed. Enock, f.i.s., f.e.s., etc. 



{Illustrated) ... ' 



Notices of Books 



Shoet Notices 



Books Rbcbited 



Letters:— J. H. Jbxkinsox {Illustrated); W. H. S. Mosck; 



II. Whichello; W. Wesche 



Artificial Faculse. By the Rev. Abthur East. (Plate) .. 

 The Objective Prism, the Flash, and the Reversing 



Layer. By E. Waltee Macndeb, f.e.A.s. (Illustrated) 



Alexander Goodman More ... ... 



How to Photograph through a Fly's Eye. By Fbed. 



W. Saxby. (Illustrated) 



Notes on Comets and Meteors. By W. F. DBNNiNa, 



f.e.A.s 



The Face of the Sky for August By A. Fowleb, f.e.A.s. 

 Chess Column. Bv C. D. Locock, b.a 



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THE PETROLEUM INDUSTRY.~III. 



By George T. Hollow.\y, assoc. r.c.s. (lond.), f.i.c. 



IT was not until 1S5'J that the use of petroleum for 

 illuminating purposes commenced to be general, 

 although lamps for burning the very similar coal oil 

 and shale oil had been introduced some sis or seven 

 years previously by Stobwasser. of Berlin, and by 

 Young's ParalSn Light and Mineral Oil Company of this 

 country. Prior to the introduction of these oils, only 

 animal and vegetable oils (excepting oil of turpentine, 

 which was employed to some extent under the trade name 

 "camphine ") had been used ; they possessed many of the 

 qualities of tallow, and were capable of being burned with 

 a small wick and with free exposure to the air. The 

 petroleum oils, however, are of an entirely different nature, 

 containing much more carbon and hydrogen than do the 

 animal and vegetable oils, and are far more volatile and 

 inflammable ; they must be supplied in a regulated 

 quantity to the flame, and with a proper amount of air, or 

 a smoky and objectionable flame results. 



The enormous number of lamps which are now in use. 



and the necessity for fixing an arbitrary limit for the 

 volatility and inflammability of the oil which may be used 

 in them, and the conditions under which the oil may be 

 stored, conveyed, and sold, has given rise to much legislation 

 in this and other countries. The differences in the laws of 

 various countries on this subject show how difficult it is 

 to decide on the standard which shall be at the same 

 time safe for the consumer and fair to those who produce 

 and supply the illuminant. As this matter is still under 

 consideration by a committee of the House of Commons, 

 it is not the intention of the writer to express an opinion 

 on the subject ; but it may be of interest to trace some of 

 the more important steps in the evolution of the mineral 

 oil lamp which have led to its present efficiency. It may, 

 however, be taken as an axiom that no oil is safe in a 

 badly constructed lamp, or when used by the careless. 



The first important improvement which fitted lamps 

 for use with mineral oils was the introduction, by Argand, 

 of the chimney, by which the requisite draught of air 

 was caused to impinge on the flame, and thus produce 

 a greater efficiency as regards illuminating power and an 

 absence of smoke. This was followed by the invention of 

 Roberts, whose lamp, specially constructed for burning 

 camphine, was fitted with a disc known as the " Liverpool 

 button," which was fixed some distance above the circular 

 wick, so as to deflect the air current downward upon the 

 top of the flame. Next came the dome which fits over and 

 round the wick, and has a slit through which the flame 

 passes ; this appliance, which is now fitted to practically 

 all oB lamps, still further directs the air between the 

 dome and the wick so that it is applied at the point of 

 maximum efficiency. In the Wanzer, and certain other 

 lamps, air is blown by clockwork or other device upon the 

 flame. Finally, we have those lamps in which two or 

 more wicks are employed, as flames thus impinging one 

 upon the other give a greater light than when burned 

 separately. 



The principal danger with oil lamps lies in a badly fitting 

 wick — which is liable to be dropped, while still alight, 

 into the reservoir — and in the use of breakable vessels. 

 Metallic reservoirs are now largely employed, and various 

 safety appliances are attached to the best forms of modem 

 lamps : for example, a flap or other appliance may close 

 over the flame and extinguish it when the lamp is over- 

 turned or unduly tilted ; and the cage of wire gauze, 

 suggested by Mr. Boverton Redwood, in which the wick is 

 enclosed so that no flame can pass from the wick to the 

 oil in the reservoir. While most accidents are not due to a 

 true explosion, but to the simple ignition of the oil through 

 the overturning or breaking of the lamp, explosions may 

 occur from the production of an explosive mixture of the 

 vapour of the oil with air in the reservoir ; and the question 

 which has been so much under discussion of late hinges 

 on whether this can be prevented by raising the " flashing " 

 point of oU, or whether it can best be dealt with by insisting 

 on the use of such lamps only as are properly suited for 

 burning the oil as at present sold. 



Legislation in this and other countries is mainly based 

 on what is known as the " flashing " point, which means 

 the temperature at which the oil gives off an inflammable 

 vapour. This is, of course, lower than is shown by the 

 fire test, i.e., the temperature at which the oil itself wUl 

 take fire. 



The Acts of 1862 and 1808 m the United Kingdom 

 included under the term "petroleum" such oil as gave 

 off an inflammable vapour at less than one hundred 

 degrees Fahrenheit by what is known as the open test — 

 that is, when warmed in a vessel exposed to the air ; but 

 as this test was found to give varying results in different 



