October 20, 1923J 



NA TURE 



581 



hydroxide " means a calculation and therefore extra 

 work. 



(3) Looked at from the point of view of a research 

 chemist of some thirty years' standing, the first feeling 

 produced on reading Prof. MuUiken's volume is one 

 of doubt as to whether the immense labour and skill 

 expended in its compilation were really worth while ; 

 the second is a sense of disappointment that, by the 

 exclusion of all references, an opportunity has been 

 lost of making the treatise of real value to research 

 workers ; for it can scarcely be doubted that the 

 work is intended for the research chemist, because 

 who else would be interested in the vast number of 

 compounds tabulated } 



The author's " method " may, and probably does, 

 do all that he claims, but it is scarcely conceivable 

 that any organic chemist would use it, even if he 

 had sufficient time at his disposal to enable him to 

 do so. The vast majority of organic chemists, when 

 they isolate a new compound, subject it first to an 

 elementary analysis and then determine its empirical 

 formula by the usual methods. They then look up 

 the formula in Richter or in one of the many annual 

 or decennial indexes based on empirical formulae, as 

 indeed they all are, and then refer to the literature. 

 Even then identification can never be regarded as 

 certain until direct comparison has been made. Physical 

 properties and chemical reactions are interesting, but 

 often misleading, and the lack of any reference to the 

 literature prevents the chemist from doing the one 

 thing he ought" to do, that is, to prepare some of the 

 material and compare it with that which he has 

 obtained. In the event of the substance being too 

 difficult or too expensive to prepare, there is another, 

 though less satisfactory, method for establishing 

 identity, and that is by preparing some crystalline 

 derivative and comparing this with the same deriva- 

 tive prepared from the standard. But here again the 

 author does not help, because he mentions no deriva- 

 tives. If he had given references and had described 

 one or two typical derivatives, the book would doubt- 

 less have been larger, but it would have been infinitely 

 more useful. 



(4) The book before us is the third edition of a 

 work which evidently finds a considerable sale on the 

 Continent. It is, as the author says, " un cours " 

 and not " un traitd," and does not, therefore, pretend 

 to cover the whole field of the special subject with 

 which it deals. Nevertheless the book contains 674 

 pages, and it should be possible to deal with most of 

 the more important aspects of the science in this 

 space. On the whole, the author has succeeded in 

 compiling a readable book, and one which should be 

 of great use to the student, provided he has facilities 

 NO. 2816, VOL. I 12] 



for acquiring help in the initial stages to fill the gaps 

 which the author has left. It is, for example, unlikely 

 that the student would obtain a working knowledge 

 of stereoisomerism or of tautomerism from the rather 

 meagre descriptions given in this book. Indeed the 

 basic theoretical parts are too short and too difficult 

 to follow. Otherwise the book is a valuable one and 

 is well printed and set up. J. F. T. 



The Composition and Examination of 

 Volatile Oils. 



The Volatile Oils. By E. Gildemeister and Fr. Hoff- 

 mann. Second edition, by E. Gildemeister. Written 

 under the auspices of the firm of Schimmel and Co., 

 Miltitz, near Leipzig. Authorised translation by 

 Edward Kremers. Third volume. Pp. xx + 777. 

 (London : Longmans, Green and Co., 1922.) 325. net. 



WITH the volume before us the English transla- 

 tion of the second edition of Gildemeister and 

 Hoffmann's " Volatile Oils " is now completed. The 

 publication of the book has unfortunately been very 

 materially delayed by the War, so that a period of no 

 less than nine years has elapsed since the appearance 

 of the first volume in 1913, and there are but few 

 references to the results of investigations published 

 since 191 5. In the second volume the oils derived 

 from plants belonging to a number of families were 

 dealt with in detail ; in the present work those ob- 

 tained from the Rutaceae (including, therefore, lemon, 

 orange, and other Citrus oils), Burseracese (myrrh and 

 elemi), Dipterocarpese (Borneo camphor oil), Myrtacese 

 (myrtle, pimento, bay, clove, eucalyptus, cajuput), 

 Umbelliferae (caraway, dill, anise, celery, ajowan, 

 asafetida), Ericaceae (wintergreen), Labiatae (lavender, 

 sage, thyme, mint), Compositae (chamomile, worm- 

 wood), and many other families, are considered. 



The thoroughness with which the task has been 

 attacked may be well exemplified by the monograph 

 on lemon oil. Tables of statistics are followed by a 

 map showing the districts of production of lemon, 

 orange, and bergamot oils in Sicily and Calabria. The 

 various methods of extracting the oil are then carefully 

 described and the descriptions illustrated by a number 

 of photographic reproductions. The properties and 

 constituents of the oil are next exhaustively dealt 

 with. Details of the chemical examination of the oil 

 occupy 24 pages. No fewer than eleven methods of 

 determining the citral present are described, and, which 

 is most important, the objections to their use, and the 

 results of the methods when tested in Messrs. Schimmel's 

 laboratory, are appended. 



Here and there in the work statements may be met 

 with that are now no longer correct ; thus on: p. 492 



