48o SCIENCE PROGRESS 



group, explaining any abnormal behaviour of organic compounds by a reversal 

 of the ordinary sign of charge of the group. This method of formulation of 

 the benzene derivatives is presented clearly and possesses considerable merit 

 in view of the complexity of the processes of substitution in the benzene ring. 



The physical properties of benzene compounds are taken into considera- 

 tion, particularly those of molecular volume, absorption spectra, fluorescence, 

 etc. The theory of absorption of ultra-violet light, by the benzene nucleus 

 is, however, open to serious criticism. Almost any series of frequencies 

 taken at random would give satisfactory agreement with the theory of 

 keto-enol tautomerism put forward by the author. 



The book does not appear suitable for degree students, but those under- 

 taking research in organic chemistry may find the author's theory suggestive 

 of new lines of work. W, E. G. 



An Introduction to Organic Chemistry. By D. LI. Hammick, M.A., Fellow 

 of Oriel College, Oxford. (Pp. viii+ 258, with diagrams). (London: 

 1921. G. Bell & Sons. Price 6s. net.) 



The present work has been written with a view to enabling beginners in 

 chemistry to become familiar with the elementary notation and technique of 

 organic chemistry earlier than is usually the case, and is not written with a 

 view to covering any special syllabus, but in order that the student may 

 start the organic portion of chemistry on level terms with the inorganic and 

 physical sections. 



The author assumes, of course, that the reader has an acquaintance with 

 elementary chemistry, and with general laboratory operations. After intro- 

 ducing the subject, and discussing the question of valency, structural formulae, 

 and methods of analysis, the book deals with the production and isolation 

 of ethyl alcohol, thence to other alcohols, and so to the discussion of homology, 

 the essential facts of which are very clearly shown in the table on page 25. 



Interspersed in the text aife suitable simple experiments which can be 

 readily carried out in the laboratory. Thence by easy stages the beginner 

 is introduced to the subjects of esters and isomerism. Chapter IV is devoted 

 to the action of sulphuric acid upon alcohol, leading to the formation of ether 

 and ethylene, thus affording an opportunity for discussing saturation and 

 unsaturation. After this the usual derivations are dealt with, such as alde- 

 hydes, fatty acids, ketones, paraffins, amides, etc., the latter half of the book 

 dealing with aromatic compounds. 



The book is essentially readable throughout, and it would be difficult for 

 anyone who has worked carefully through the text, and the experiments, 

 not to have had his interest and even his enthusiasm aroused for the wonders 

 of organic chemistry, which may serve to carry him forward through the 

 occasionally more tedious parts of the subject when he comes to tackle the 

 larger textbooks. 



Mr. Hammick has succeeded in condensing the elements of organic 

 chemistry into small compass with great skill, and those requiring an intro- 

 ductory textbook on the subject will do well to consider the book carefully. 



F. A. M. 



Organic Analysis, Qualitative and Quantitative. By E. de Barry Barnett, 

 B.Sc, F.I.C., and P. C. L. Tkorne, M.A., A.I.C. [Pp. xi + 168, with 

 31 illustrations.] (London : University of London Press, Ltd., 1921. 

 Price 7s. 6d. net.) 



Part I of this book gives the usual tests for the elements and for separating 

 the substances under examination into classes depending on the elements 



