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THURSDAY, JULY 18, 1895. 



ANALYSIS OF OILS, FATS, AND WAXES. 

 Chemical Analysis of Oils, Fa/s, and JJ'tLXCs, and of the 

 Commercial Products derived therefrom. From the 

 (icrman of Prof. Dr. R. liencdikt. Revised and en- 

 larged by Dr. J. Lewkowitsch, F.I.C., F.C.S. (London : 

 Macmillan and Co., 1895.) 



TEN or tvvehe years ago, the analysis of oils was 

 one of the most neglected branches of an.^iytical 

 chemistry. How the study of it has been taken up and 

 de\elopcd since, may be gathered by turning over the 

 670 pages of this excellent volume, the first English work 

 devoted exclusively to this subject. The information 

 existing in 1882 was comprised within 140 pages (much 

 smaller than these) of Allen's " Commercial Organic 

 Analysis." In the second edition of the same work, 

 published in 1886, the subject-matter had grown to 318 

 pages. Benedikt's " Analyse der Fette und Wachsarten," 

 second edition, published in 1892, upon which the present 

 work is based, contained 460 pages, and as the literature 

 of the subject has accumulated since then, at an in- 

 creasingly rapid rate, it is evident that a new volume was 

 demanded, the preparation of which could not have 

 devolved upon any one more capable than Dr. Lew- 

 kowitsch, whose practical experience in, and valuable 

 contributions to, our knowledge of this branch of chemistry 

 are well known. To regard this work merely as a trans- 

 lation of the work of Dr. Benedikt would, obviously, be 

 aljsurd. As the author points out in the preface, every 

 page bears evidence of the alterations and numerous 

 adilitions which have been made. Obsolete processes 

 have been abridged or entirely omitted, and the new work 

 of the last four years has been sifted, and all that is of 

 value has been incorporated, including a large number of 

 the author's own experiments and observations hitherto 

 unpublished. Benedikt's arrangement of the subject- 

 matter has been generally adhered to, but an improve- 

 ment has been effected by transferring to the end of the 

 book the chapter on the analysis of soap, candles, glycerine, 

 and other products of the fat industry. 



The first two chapters contain a description of the 

 sources and chief properties of the various acids and 

 alcohols obtained, or derived by oxidation, from the 

 fats and waxes, followed by an account of the chemical 

 constitution and thechief chemical and physical characters 

 of the oils, fats, and waxes themselves. Commercial fats 

 and oils are not pure neutral bodies, but always contain 

 more or less free fatty acids which, for some purposes, 

 depreciate their value. The percentage of free acid is 

 liable to increase on keeping, and it was until recently 

 believed that the development of rancidity was connected 

 with this change. But Ballantyne has disproved this 

 by showing that an oil may become lancid without 

 becoming acid, and Heyerdahl has proved that the 

 converse may also be true. The discovery, by Kirchner, 

 of micro-organisms in poppy-seed oil, lent support to the 

 view that rancidity might be the result of a fermentation 

 process ; but Ritsert sliowed that a fat which had been 

 sterilised by heating to 140' C, might subsequently become 

 rancid if exposed to light and air. The latter investigator 

 has also shown that moisture is by no means essential, 

 NO. 1342, VOL. 52] 



and he has finally concluded that rancidity must be due 

 to the direct oxidation of the oil or fat by the oxygen 

 of the air acting in presence of light. 



Chapter iii. describes the determination of water and 

 other non-fatty admixtures, and the preparation of the 

 pure fat for analysis. Then follow a chapter on the 

 physical properties and methods of examining fats, and 

 four chapters on chemical methods. In the two next 

 chapters the application of the foregoing, and some other 

 methods, to the examination of fats is discussed, and 

 data obtained by submitting the various oils, fats, &c., 

 to examination by each method are collected and arranged 

 in tables. This, however, is hardly shown by the head- 

 ings of the chapters. Thus, chapter iv., which is headed 

 " Physical Properties of Fats and Waxes," should rather 

 be " Physical Properties and Methods of Examining 

 Fats and Waxes" ; and chapters ix. and x., headed 

 " Systematic Examination of Liquid and Solid Fats and 

 W' axes," with the sub-headings " Physical Methods " and 

 " Chemical Methods," would be better entitled " Applica- 

 tion of the foregoing Methods to the Systematic Ex- 

 amination," &c., with sub-headings " Application of 

 Physical Methods " and " Application of Chemical 

 Methods." These eight chapters are admirably written, 

 and the value of the information given is greatly enhanced 

 by the able manner in which each method is discussed 

 and criticised. The completeness of the treatment shows 

 how thoroughly the author has ransacked the literature 

 of the subject. Unfortunately the task of reading and 

 sifting papers is rendered heavier than need be by the 

 growing tendency to rush into print with trivial and ill- 

 considered observations. Thus, " the excellent Reichert- 

 Meissl process has not escaped the fate of nearly all 

 modern methods used in fat analysis " (there is no need 

 to limit the statement to fat analysis, as the literature 

 of steel analysis would show), " viz., to receive at the 

 hands of numerous analysts a number of supposed 

 improvements, most of which are altogether insignificant 

 and hardly offer any advantage whatever." Again, re- 

 ferring to the Hiibl process : " The chemical literature 

 of the last few years contains numerous papers by various 

 authors purporting to give improvements or modifications 

 of the original method. Most of these refer to minor 

 and unimportant points, and some of them even reproduce 

 methods which Hiibl in his classical paper has rejected." 



For the determination of unsaponifiable matter, the 

 author recommends petroleum spirit in preference to 

 ether, but he very rightly insists upon the necessity of 

 carefully purifying and rectifying the spirit used. If this 

 is not done, some of the lighter mineral oils occasionally 

 used to adulterate rape oil, for instance, may be lost, and 

 for that reason I prefer to use ordinary ether, which can 

 be completely expelled at a very moderate temperature. 



For the determination of resin, Twitchell's process is 

 recommended as yielding the best results, but no process 

 yet exists by which resin can be determined with absolute 

 accuracy. 



" If a correct nuthod of determining accurately the 

 oxygen absorbed were known, it would be possible to 

 class the determination of the drying power, or, as it 

 might be called, the 'oxygen value' amongst the quan- 

 titative reactions." Such an addition to existing methods 

 would be of the greatest value in the examination of the 



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