January 29, 1915] 



SCIENCE 



167 



jeet-matter in eleven chapters, of whicli the 

 titles are as follows : Historical — The Measure- 

 ment of Light Quantities — The Energetics of 

 Radiation — Economic and Energetic Relations 

 of Actual Light Sources — The Absorption of 

 Light — Statics and Kinetics of Photo-chemical 

 Change — ^Dynamics of Photo-chemical Change 

 — Special Photo-chemistry — Radiant Matter 

 and Photo-chemical Change — The Genesis of 

 Light in Chemical Change — Organic Photo- 

 synthesis. 



The first four chapters do not carry us 

 much beyond photo-physics, but give a very 

 satisfactory resume of those divisions of 

 optical physics vehich are of primary impor- 

 tance in photo-chemistry. Beginning with 

 Chapter V., the subject-matter becomes in- 

 creasingly chemical in character, and the book 

 ends with an excellent account of the more 

 recent investigations into the character of the 

 chlorophyll reactions. 



To the reviewer the author's method of 

 treatment seems most commendable. Such 

 principles as may be considered thoroughly 

 established are treated with scientific concise- 

 ness and brevity, not in general, however, 

 without the presentation of sufiicient numer- 

 ical data for illustration. In dealing with 

 matters which are still in the formative stage, 

 a condition true of so much of photo-chemistry, 

 the author does not dogmatize, but usually 

 leaves the reader with quite the impression 

 that the state of knowledge concerning the 

 subject warrants. This makes the book valu- 

 able not only for the knowledge which it im- 

 parts, but also for its stimulus to critical 

 thinking. 



The book is made up quite directly from the 

 original literature of the subject and is amply 

 provided with citations and references. The 

 author's personality shows itself not only in 

 the thoroughness with which the material has 

 been digested and assimilated, and later organ- 

 ized for the purpose of clear presentation, but 

 also in not infrequent elucidating discussions 

 and in occasional flashes of imaginative ex- 

 planation. The reviewer's impression is that 

 we have here the work of one thoroughly im- 

 bued with his subject, and at the same time 



entirely competent to handle it. The book 

 should prove valuable not only to those desir- 

 ing admittance to the charming mysteries of 

 photo-chemistry, but should also be welcome 

 as an additional weapon in the armory of the 

 initiated. 



S. W. Young 

 Stanfoed University 



The Hydrogenation of Oils; Gaialyzers and 

 Catalysis and the Generation of Hydrogen. 

 By Carlton Ellis. New York, D. Van 

 Nostrand Co., 1914. Price $4.00 net. 

 The book considers very fully the methods 

 of hydrogenation, the various catalyzers, both 

 the base and rare metals, and the mechanism 

 of hydrogen addition. Besides this, the sub- 

 jects of the analytical constants of the oils 

 and their uses both for culinary purposes and 

 soap making are thoroughly dealt with. About 

 one third of the book is devoted to the methods 

 for the generation of hydrogen, which is of 

 prime importance: these include water gas, 

 decomposition of hydrocarbons, steam on 

 heated metals, acids on metals, the electrolysis 

 of water, and the safety devices for handling 

 the gas. 



A feature of the book is the very complete 

 citation of references and patents from the 

 three principal languages. 



The volume satisfactorily fills a decided want 

 and may be unreservedly recommended to all 

 interested. 



A. H. Gill 



A Text-looh of Medical Entomology. By 

 Walter Scott Patton, M.B. (Edin.), 

 I.M.S., King Institute of Preventive Medi- 

 cine, Madras, and Francis Willm.m Cragcj, 

 M.D. (Edin.), LM.S., Central Research 

 Institute, Kasauli, Punjab. Christian Liter- 

 ature Society for India, London, Madras 

 and Calcutta. 1913. Pp. xxxiv + Y68. 

 84 pis. £1-1-0. 



The protozoologist, parasitologist or physi- 

 cian who has occasion to deal with the arthro- 

 podan carriers of diseases produced by bac- 

 teria. Protozoa, or nematodes, has long been 

 hampered in his investigation by reason of 



