— 108 — 



decomposition by oxidation, with notes on the specific behaviour of 

 the various oxidising agents; reactions of condensation and ring-form- 

 ation; and the rupture, and extension of ring-systems. After an exposition 

 of the origin and behaviour of the most important types of combin- 

 ations which are met with in practice, we have chapters on physical 

 properties, constitutional relations, syntheses, division and nomenclature. 

 An extensive review of all the combinations which have been examined, 

 systematically arranged, and' containing accurate and complete references 

 to the literature of each combination, brings the general part of the 

 work to a close. 



The second, or "special" section contains, in concise form, the 

 vast positive experimental material dealt with in Wallach's public- 

 ations. This is arranged in the 19 principal groups which have, in 

 practice, served as bases of investigation, viz., Pinene, Pinol, Limonene, 

 Terpinolene, Terpine and Terpineol, Cineol, Carvone, Eucarvone, 

 Pulegone, Menthone, Monocyclic Ketones, Terpinene, Phellandrene, 

 Sylvestrene, Sabinene, Thujone, Fenchone, Camphor, and Sesquiterpenes. 

 Each of the principal divisions in this section is preceded by an in- 

 troductory chapter giving a brief general review of the particular field 

 covered. 



Wallach's work affords ocular demonstration of the wideness of 

 the field which this famous investigator has thrown open to scientific 

 research, and also shows how large a share he has had in its deve- 

 lopment. It will be of special interest and great usefulness not only 

 to his pupils, to whom it is dedicated, but to all other workers in 

 this branch of science. 



The third part of the second volume of the third edition of 

 Posts Chemisch-technische Analyse which has been edited by B. Neu- 

 mann, contains a chapter on essential oils by J. Helle. The 

 author first describes briefly the manner of testing the raw materials 

 and then enters in detail into the physical and chemical testing of 

 essential oils, in the course of which, besides dealing with the generally 

 applicable methods, he considers a few special processes, such as, for 

 example, the determination of cineol, hydrocyanic acid, isothiocyan- 

 allyl, etc. The detection of the most common adulterants is also 

 discussed at length. A tabular review of the properties and compos- 

 ition of the principal essential oils brings this little work to a close. 

 The book will no doubt prove a good and reliable guide for technical 

 chemists in the analysis of essential oils. 



A second edition of Ernest J. Parry's well-known work The 

 Chemistry of Essential Oils and Artificial Perfumes has been published 

 (Scott, Greenwood & Son, London, 1908), with the object of recording 



