BOOK REVIEWS. 



133 



" Soil Biology : Laboratory Manual." By A. L. Whiting, Ph.D. 8vo. 

 ix -+- 143 pp. (Chapman & Hall, London, 1917.) 6s. net. 



Soil Chemistry and, to a certain extent, Soil Physics have long since found 

 their place in school and college courses in Agriculture ; but the equally 

 important biological aspect of soil conditions has not only been less studied, 

 but even those parts that are most intimately known have been more or less 

 neglected as subjects of practical study in such courses. This is not as it should 

 be, and it is to be hoped that this little book of practical exercises and questions 

 will help to introduce this side of soil science more to the notice of the teacher 

 and bring it more prominently before those framing courses of instruction for 

 agricultural and horticultural students. The proof of the pudding is in the 

 eating, and until the exercises contained in this little book have been worked 

 through practically and their practicability determined, it is too soon to speak 

 of the merits of the exercises in detail, but at any rate it is plain that the plan 

 of the book is good, and to follow out its exercises cannot fail to be of value 

 to the student. 



" The Natural Organic Colouring Matters." By A. G. Perkin and A. E. Everest. 

 8vo. xxii -f- 655 pp. (Longmans, Green & Co. London, 1918.) 28s. net. 



This volume forms one of the series of Monographs on Industrial Chemistry 

 edited by Sir E. Thorpe. It deals with the natural organic dyestuffs and takes 

 no account of those colouring matters such as chlorophyll, haemoglobin, and 

 the carotinoids, which possess no real tinctorial properties. It is quite rational 

 to exclude pigments of the latter type, which form a class apart, the inclusion of 

 which in a monograph on Industrial Chemistry would be unwarrantable; but 

 the title of the book is slightly misleading if read literally. The natural organic 

 dyestuffs themselves form a sufficiently big subject, and it is not surprising 

 that the book runs to nearly seven hundred pages. 



As is to be expected from authors so well qualified to deal with this subject, 

 a most comprehensive and detailed account of the occurrence, extraction, con- 

 stitution, properties, and uses of the natural organic dyestuffs is given. Indeed, 

 it is doubtful whether so exhaustive a treatise can truly be described as a mono- 

 graph in the usually accepted sense of the term at the present time, as applied 

 to members of series of books devoted to special groups of subjects, namely a 

 short, concise (and therefore moderately priced) volume giving the essentials 

 of a subject, and capable of being readily brought up to date and reissued from 

 time to time. A book of the size and price of that under review scarcely answers 

 this description. However, it must not be thought that we quarrel with the 

 subject matter or with its presentation : both are excellent. 



The dyestuffs are classified according to the chemical constitution of their 

 main tinctorial constituents. As examples of the scope of the book it may be 

 mentioned that seventy-eight pages are devoted to the anthraquinone group, 

 including madder, cochineal, and kermes 1 one hundred and ten pages to the y 

 pyran group of anthocyanin dyestuffs ; and fifty-four pages to the indole 

 group, including indigo, woad, and Tyrian purple. A chapter is included on 

 the tannins, which, although not strictly dyestuffs, are of importance in dyeing 

 operations, and a short account is also given of lakes formed from vegetable 

 colouring matters. A list of natural dyestuffs classified according to their botanical 

 origin forms a useful Appendix. A valuable feature is the wealth of scientific 

 and historical references to the original literature. 



The text is on the whole clearly written, though the style is awkward at 

 times, and there are a few evidences of inadequate proof correction, such as 

 " exiccator," " unusual great solubility," and " to invariably accompany." 

 These are minor blemishes, and the book can be unhesitatingly recommended 

 as a valuable work of reference to all interested in the chemistry of the natural 

 organic dyestuffs. 



" Recent Advances in Organic Chemistry." By Alfred W. Stewart, with 

 an Introduction by J. Norman Collie. Third edition. 8vo, xix + 350 pp. 

 (Longmans, Green & Co. London, 1918.) 14s. net. 



The previous editions of Dr. Stewart's well-known book were outstanding 

 examples of his happy faculty of combining lucid exposition with shrewd criti- 

 cism, in an eminently readable form. This new edition is certainly not inferior 

 to its predecessors in these respects, and is sure of a hearty welcome from all 

 organic and bio-chemists. Research workers will find it most useful in keeping 

 abreast of progress in fields other than their own, while for advanced students 

 its influence in encouraging their critical faculty and in suggesting subjects 

 for research should be invaluable. 



It is significant of the healthy reaction in favour of the study of the organic 



