THE ANALYST. 119 REVIEW. CHEMICAL ANALYSIS OF OILS, FATS, AND WAXES, AND OF THE COMMERCIAL PRODUCTS DERIVED THEREFROM. From the German of Professor Dr. R. BENEDIKT. Revised and enlarged by J. LEWHOWITSCH. (Macmillan and C o . , 1895. $1 Is.) Before entering into a discussion of the contents of this valuable work, we must take exception to the English editor’s opening sentence in the preface, that I L there has not hitherto been any English work deFling especially with the chemical analysis of oils, fats, and waxes.” One of the volumes of Mr. Allen’s great work on I L Com- mercial Organic Analysis ” deals most “ especially ” with the subject. Dr. Alder Wright’s work, which, by the way, has the right of priority to the title chosen by Dr. Lewkowitsch, and which was published only last year, also deals ( ( especially ” with it, to say nothing of the numerous fairly complete monographs inserted in several chemical encyclopedias and dictionaries.The English editor of the work under review might have given credit where credit was due. To Mr. Allen in particular we owe so much of our knowledge of the composition, knd what is the same, of the analysis of oils, that no writer for years to come can afford even to appear to overlook his work. The reader cannot fail to be struck with the fact that of late years by far the greater part of the advance which has been made in the knowledge of the chemistry of oils is due to the analytical chemist, and not to the academical investigator, With the exception of the work of Hazura and his coadju’tors (a work which stands in urgent need of confirmation and development), no very important addition has been made to the broad theoretical foundations laid long since by Chevreul and Liebig and their pupils, while, on the other hand, the analyst has most industriously multiplied and developed his methods.The measure of the proportions of free fatty acids, and of the amount of alkali requisite for neutralizing the total fatty acids, the measure of the proportions of the glycerides, volatile fatty acidg, the insoluble fatty acids, hydroxyacids, and of the unsaturated fatty acids, with the isolation and determination of the alcohols, and other unsaponifiable matters, are all advances made during the last twenty years, and most of them are of still more recent origin.These now supply analytical data of infinitely higher scientific value than the old colour reactions and physical differences with which the last generation of chemists contented themselves. The work deals most fully and clearly with the determination of these ‘ 6 constants ” of fatty and allied bodies, and with their interpretation. From the general part of the work, the intelligent student will at once realize that there is still need for a vast amount of further investigation. Essentials, like the separation of unsaturated from saturated acidg, the determination of one saturated fatty acid in the presence of others, the quantitative estimation of the various groups of the unsaturated fatty acids, are even now almost in embryo, and until these and other allied problems are fully solved, accurate fat analysis will remain an impossibility.Indirect methods, it is true, exist in plenty, but none of these are beyond criticism, and many involve assumptions which are unwarranted. Thus120 THE ANALYST. the indirect determination of palmitic and stearic acids from the molecular weight, as deduced from the titration of a mixture, presupposes that only the two acids named are present, and the proof of this is hardly ever obtainable. More complex still is the problem when unsaturated acids are present. The iodine number is often translated into percentages of oleic acid ; but this is obviously wrong, unless there are no acids with less hydrogen than oleic present, yet no adequate means are at hand to prove their absence.The special parts of the work, dealing with the constants and properties of individual oils, fats, and waxes, are very complete, and contain an immense amount of information. The tabular statements interspersed throughout this part are particularly valuable, and in this respect the work is an improvement on the original edition of Benedikt. Never before has so large a mass of similar material, for the most part trustworthy, been collected together. Had the authors done no other work than thus to collect data, they would have laid chemists under a great obligation; but when the whole scope of the work is considered, it can safely be said that no chemist who is called on to analyse fatty bodies can afford to be without the book. We must specially mention its value to the public analyst, though we are sorry to see that THE ANALYST is a journal apparently little known either to the author or his translator.Several important contributions, especially on the subjects of butter and lard, which were originally published in THE ANALYST, are attributed to other journals, erroneously described, or wholly ignored. As regards butter, the reference to adulteration with clay, chalk, gypsum, and fiour, might with advantage have been omitted. The conversion of Reichert numbers into Reichert-Wollny figures by multiplication of the former by 2 is unjustifiable, the factor being more nearly 2.2. There are a few errors in the book, taken over by the English editor from the German author. Thus, in Herbig’s modification of the Benedikt-Zigmondy method for the determination of glycerin (p.163), the amount of permanganate requisite is not clearly given-6.87 parts for one of glycerin are insufficient, half as much again being absolutely necessary, or the results will be found too low in almost all cases. The method for the analysis of beeswax, depending upon the determination of the acid value and the ether value, is erroneously attributed to Hiibl; and it is further stated that ‘‘ Hehner adopts Hiibl’s method, with the only difference that he substitutes methyl alcohol for ethyl alcohol,” etc. Hiibl’s paper on wax analysis was published in the September number of Dingler’s Polytechnisches Journal, 1883, the date of the writing of the paper being July, 1883. Hehner’s paper was read before the January meeting of the Society of Public Analysts, and was published in the February number of THE ANALYST, 1883, six months before the appearance of Hiibl’s paper. It is quite possible that Hiibl’s work on the subject was quite independent, but it was certainly not antecedent. Benedikt, like most other German authors, not understanding the mysteries of methylated spirit-a product peculiar to England, and a curse to English chemists-translates inethylated spirit as “methyl alcohol.” But the English editor might have known better than to repeat the error, which a glancg at the original paper would have prevented. But these mistakes and omissions are trifles compared with the mass of sound information contained in the book, which we cordially recommend to the readers of THE ANALYST, partly on account of its intrinsic value, but more strongly still on account oE the help and stimulus it must prove to investigators of B particularly difficult and importrtnt division of chemistry. 0. H.