i873«] Notices of Books. 119 



correct in data, terse, practical, and smooth in diction. The 

 author takes a very modest position. He says : — "As treated in 

 the following pages the subject admits of no originality, and the 

 author claims none; his object has been to deal with it in as 

 simple and popular a manner as possible, and to point out the 

 injurious effects produced on health by impure air and water, the 

 sources and origin of their impurities, with the means for their 

 detection, and the several methods by which they may be 

 removed or remedied." Taking the first two pages as a test of 

 the amount of information conveyed, we find, in the course of a 

 brief discussion of the causes of atmospheric impurity, a state- 

 ment of the normal constituents of atmospheric air, their 

 properties and quantitative relation, the preparation and uses of 

 ozone and the method of testing for its presence, and a word or 

 two concerning the suspended impurities of air. The work goes 

 on to consider the causes which render air impure, the effects of 

 respiration, putrefactive emanations, sewer gas (with useful hints 

 for remedying it), the methods of detecting organic impurity in 

 air, the natural laws for the purification of the atmosphere, 

 ventilation, disinfection, and the hygiene of the sick room. 



The second part of the book deals with the impurities of water 

 and their removal. The causes and effects of water contamina- 

 tion, and the relation of typhoid fever and cholera to impure 

 water (a subject on which people will find it greatly to their 

 interest to be enlightened), are well, but briefly, discussed. The 

 description of methods of detecting the impurities of water is 

 succinct, but yet up to the time. Dr. Burdon Sanderson's 

 " zymotic test " is noted, and the methods of detection of nitro- 

 genous matter are simply put. The little volume concludes with 

 hints on the removal of impurities from water. 



We recommend it to all ; to those whose scientific labours, 

 directly or indirectly, tend to advance or to apply the knowledge 

 of hygiene, — they will find it a useful compendium ; to all others 

 whose occupation is in other grooves, but who nevertheless have 

 a personal interest in the preservation of health, — they will find 

 it an easily intelligible and most valuable guide. 



A Manual of Microscopic Mounting ; with Notes on the Collection 

 and Examination of Objects. By John H. Martin, Author 

 of "Microscopic Objects," &c. Illustrations drawn by the 

 Author. 200 pp., 8vo. n plates. London: J. and A. 

 Churchill. 



The subject-matter of this volume is divided into seven chapters 

 and an appendix. 



The first treats on various apparatus employed ; in many in- 

 stances directions are given for construction, and some of the 

 author's own contrivances are described. Chapters 2, 3, 4, 



