NA TURE 



2 [ I 



THURSDAY, AUGUST 19, 1909. 



OILS, FATS. AND WAXES. 

 Chemical Technology and Analysis of Oils. Fats, and 

 Waxes. By Dr. j. Lewkowitsch. Fourth edition, 

 entirelv re-written and enlarged. 3 vols. Vol. i., 

 pp. xx+542 ; vol. ii., pp. xi+Si6; vol. iii., pp. viii 

 + 406. (London : Macmillan and Co., Ltd., 1909.) 

 Price 2/. los. 



THE third edition of this work was reviewed in 

 these columns about five years ago (vol. Ixx., 

 p. 502). It is therefore unnecessary again to describe 

 the plan of the book in any detail. In the broad 

 outlines it remains unaltered, though there are 

 changes in the arrangement, and considerable addi- 

 tions. 



Much has been done, and much written, in this 

 branch of technology since 1904 ; wherefore the 

 author has found it necessary to expand the work 

 into three volumes. Broadly speaking, the first 

 volume describes the general chemical constitution of 

 oils, fats, and waxes, and the usual physical and 

 chemical methods adopted in examining them ; 

 vol. ii. treats of the individual natural products; 

 and the third volume is devoted to the various groups 

 of manufactured articles, such as edible oils, oxid- 

 ised oils, candles, soaps, and gl\-cerin. Some new 

 sections, dealing with emulsified oils, the fatty-acid 

 industrv, and_ wax technology, have been added to 

 this part of the work ; and more space than formerly 

 has been allotted to the description of manufacturing 

 operations. 



Apparentlv no pains have been spared in making 

 the book as complete and as modern as possible. So 

 far as the reviewer can judge by testing the in- 

 formation here and there, no recent work of import- 

 ance on the theoretical and scientific side has been 

 overlooked. Thus Bomer's process for the identifi- 

 cation of pure glycerides is summarised, and a de- 

 scription is given of the " direct " method for 

 isolating and determining glycerol recently proposed 

 by Shukofif and Schestakoff. Valenta's suggested 

 method of quantitatively separating aromatic hydro- 

 carbon oils from those of the aliphatic series by 

 extraction with dimethylsulphate is dealt with at 

 some length ; and an account is also given of the 

 criticisms of the process by subsequent workers. 



On the technological side an interesting develop- 

 ment is mentioned which may prove of some im- 

 portance in the candle industry. A large quantity 

 of liquid oleic acid occurs as a by-product, and one 

 of the standing problems of the industry has been 

 to find some mode of converting this liquid acid into 

 its solid homologue, stearic acid, thereby rendering 

 it available as a material for candle-making. Many 

 suggestions have been made, and many patents ob- 

 tained, with this object in view ; but no great success 

 has hitherto attended these efforts — at least, on a 

 manufacturing scale. It seems, however, that an 

 application of Sabatier and Senderens' classical re- 

 searches upon the " reduction " of organic compounds 

 by means of finely-divided nickel mav mark a new 

 XO. 2077, VOL. 81] 



stage in the matter. Several investigators have pro- 

 posed such an application, and Dr. Lewkowitsch 

 states that, by a systematic study of the Sabatier and 

 Senderens reaction, he has recently succeeded in 

 converting oleic acid mto practically the full quantity 

 of stearic acid theoretically obtainable from it. 

 What, however, is not quite clear is whether the 

 translation from laboratory experiments to factory 

 practice has been successfully accomplished. Details 

 are withheld. 



The author gives a tabulation of oils, fats, and 

 waxes based upon the magnitude of the iodine values. 

 He looks upon this as the most convenient classifi- 

 cation for practical purposes. Probably it is; but 

 there are, as would be expected, some inconsistencies 

 and overlapping of groups in this arrangement. 

 Thus certain of the non-drying oils have a greater 

 iodine value than some of the drying and semi-drying 

 oils. But as every chemist dealing with diverse 

 varieties of oils and fats probably constructs some 

 such table for himself, it will be useful to have a 

 fairly complete tabulation of critically-selected values 

 for general reference, even though it is not an ideal 

 basis of classification. 



Turning for a moment to commercial matters, 

 most people know that we import large quantities of 

 butter into this country, but many may be surprised 

 to learn that lard is imported to the value, roughly, 

 of five millions annually, and another million pounds' 

 worth, our author calculates, is made at home. The 

 section of the book devoted to this important fat has 

 been increased considerably. Some of the statements 

 made in the earlier editions have had to be modified 

 — notably as regards the range of iodine values — but 

 this was only to be expected, in view of altered cir- 

 cumstances of production. The author discusses at 

 some length the difficult problem of detecting small 

 admixtures of beef-fat with lard. Tables are quoted 

 showing the melting-points of the crystals which 

 deposit from solutions in ether of lard and beef-fat, 

 respectively. The beef-fat crystals have much the 

 lower melting-point. It seems, however, to have 

 escaped the author's notice that the crystals obtained 

 from a mixture of beef-fat and lard have also a lower 

 melting-point than those from lard alone. LTsed with 

 discretion, such as the author wisely inculcates in 

 other matters, the importance of this fact in solving 

 the problem is obvious. 



In dealing with the adulteration of butter the 

 author stigmatises as futile the attempt to prove 

 " that an admixture of beef-fat or lard has taken 

 place if only low titration-numbers for the insoluble 

 volatile acids are found." Undoubtedly such an 

 attempt is futile. It is so obviously futile as to raise 

 a shrewd suspicion that there has been a misunder- 

 standing somewhere. 



In some minor matters we do not always see eye 

 to eye with the author. For example, he unduly 

 minimises the value of the specific gravity indications 

 in the examination of butter-fat. His objection is 

 that the test " would hardly lead to the detection of 

 smaller quantities of an adulterant than 30 per cent." 

 In a sense, that is true; but it is also true, in a 



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