'394 Notices respecting New Books. 
The Polarity of Matter. By Alex. Clark, M.A. 
London: Gall & Inglis. 1907. Pp. viii-f 134. 
" The atmospheric air is a maguetisable substance.'' ....*• When 
iron filings are placed on a sheet of paper over the poles of a 
magnet, each fragment forms a small portion of an elliptic curve. 
These curves do not represent lines of force, as sometimes sup- 
posed, but merely the posture in which the particles are carried 
towards the magnet.'*' . . . . " Electricity, therefore, is merely a 
modified form of the force inherent in the particles of matter, and 
is the same force which in other circumstances we call gravita- 
tion." . . . . " Having arrived at the parting of the ways, Hertz 
unfortunately took the wrong turn. Instead of accepting the 
conclusion that they (Hertzian waves) are heat waves, and 
endeavouring to account for their magnetising effect, he assumed 
the identity of electricity and light, which is impossible." Thus 
our author ; and we are left wondering how this book ever came to 
be published. 
Guide de Preparations Organiques a V Usage des Etudiants.'-'Par 
E. Eischer. Traduction autorisee d'apres la septieme edition 
allemande par H. Decker et Gr. Dusast. Paris : Gauthier- 
Yillars. 1907. Pp. xviii + 110. 
This small laboratory guide should prove of great assistance to all 
students entering on a course of laboratory work in organic 
chemistry. In the selection of the preparations, the author was 
guided partly by the price of the necessary materials and appa- 
ratus, partly by the time required to carry out the various operations 
described, and partly by considerations of safety. The author 
wisely devotes the introductory portion of the w"ork to the precau- 
tions to be observed by the experimenter in order that accidents 
may be avoided. The book is divided into two parts, Parti, being 
devoted to preparations of importance to professional chemists, 
and Part II. to compounds which are of special interest to the 
biologist or medical man. An index of the various compounds 
dealt with completes this excellent little work. 
DieBinoJcidareR Instrumente. Xach Quellen bearbeitet von Moritz 
tox Eohr. Berlin: Julius Springer, 1907. Pp. viii-|-2:24. 
This monograph deals in a thorough manner with the theory and 
history of binocular instruments. Its preparation must have 
involved a great deal of labour and patient study, and the author 
is to be congratulated on having rendered a very valuable service 
to manufacturers of binocular instruments and others interested 
in the subject, by bringing together in a comparatively small 
volume so much useful information, and more especially by placing 
before his readers so thorough a survey of the history of the 
subject. Some idea of the amount of historical research 
embodied in this volume may be gathered from the bibliography of 
