A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 Of Nature trusts the mind which builds for aye. 



-Wordsworth. 



THURSDAY, SEPTEMBER 2, 1915. 



THE EXAMINATION OF HYDROCARBON 

 OILS. 



The Examination of Hydrocarbon Oils and of 

 Saponifiable Fats and Waxes. By Prof. D. 

 Holde. Authorised translation from the fourth 

 German edition by Prof. E. Mueller. Pp. xv + 

 483. (New York : J. Wiley and Sons, Inc. ; 

 London : Chapman and Hall, Ltd., 1915.) Price 

 215. net. 



THE important part played by liquid fuel, both 

 for steam raising- and in the internal com- 

 bustion motor, has focussed a large amount of 

 attention upon the examination of hydrocarbon 

 oils for commercial use, whilst the many "crack- 

 ing- " processes that have been introduced to 

 supplement the supply of the lighter fractions of 

 petroleum for motor purposes have considerably 

 increased the interest felt in the somewhat in- 

 volved actions, partly analytic and largely syn- 

 thetic, that under the influence of heat and pres- 

 sure bring about such profound changes in the 

 characteristics of the oils. 



Under these conditions any book dealing with 

 the analysis of such oils would have been wel- 

 comed, and Dr. Holde has made the fourth edition 

 of his work on the examination of hydrocarbon 

 oils more attractive and at the same time more 

 useful by introducing^ chapters on the tars obtained 

 by the distillation of coal, lignite, shale, and peat, 

 on saponifiable fats and the technical products 

 prepared from them, and on waxes. 



The first chapter occupies more than half the 

 book, and deals with petroleum and petroleum 

 products. After touching upon the occurrence, 

 chemical composition, and formation of petroleum, 

 there is an excellent section on its physical 

 NO. 2392, VOL. 96] 



examination, followed by one on its chemical 

 treatment, in which the flash-point is apparently 

 given as the measure of the inflammability of 

 the oil, the paragraph being headed " Inflam- 

 mability," whilst a few pages later another para- 

 graph is devoted to "Burning Point." The 

 chemist knows perfectly well what is meant by 

 flash and burnings points, but the non-initiated, 

 when told that naphtha has a flash point of 

 - 21° C. and a burning- point of — 19° C, gets an 

 uncomfortable feeling- that the material is too in- 

 flammable to have anything to do with, and before 

 it is possible to clear up properly the muddlement 

 that these terms have created it will be necessary 

 to determine the igniting points of the various 

 hydrocarbons present in petroleum, which vary 

 from 400° C. to 700° C. 



. In deaUng with the calorific value of naphthas 

 for internal combustion motors the reader is told 

 that "it is determined in a bomb," but no details 

 are given as to how the dangers and difficulties of 

 such a determination with a highly volatile spirit 

 are to be got over. In discussing Hensler and 

 Engler's combustion method for the determination 

 of sulphur in oils, the dweller in a manufacturing 

 town will be amused to read that since the labora- 

 tory air often contains sulphur, the tubes to supply 

 the air for combustion are led into the open air; 

 as 10 to 12 grams of oil are burnt in five hours, 

 the sulphur from the air of even London would 

 amount to more than the oil probably contained. 



In many technical applications the book is 

 scarcely up to date; for instance, we are told 

 that " an attempt has been made " to cover the 

 surface of roads with tar or oil, and later, "the 

 tar applied hot is brushed into the street." The 

 reader is also informed on p. 44 that "the gaso- 

 line used in pleasure vehicles should have no more 

 than 5 per cent, of those components which boil 



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