Notices respecting New Books, 189 



remain unrealized. But the large amount of experimental work 

 done in eouuection with selenium has greatly added to our know- 

 ledge of this interesting element. As many of the researches 

 have up to now remained in a form not readily accessible, the author 

 of the present monograph on the subject, which forms the latest 

 addition to the Attualitd Seientificlie, has performed a very useful 

 service by bringing together the results of the various investigations, 

 and supplying a comprehensive bibliography relating to the subject. 

 In Chapter I. we are introduced to the principal physical pro- 

 perties of selenium, its density, specific heat, behaviour with regard 

 to temperature, coefficient of expansion, &c. Chapter II. deals with 

 the variation of its resistivity, Chapter III. with the effect of light 

 on itscontact-E.M.F., Chapter IV. with selenium cells, Chapter V. 

 with the causes of the photo-electric behaviour of selenium, while 

 the closing Chapter VI. contains an account of the more important 

 practical applications of the element. 



Die RiecJistoffe. Von Dr. Georg Cohn. Braunschweig : F. Vieweg 

 uud Sohn. 1904. Pp. vi+220. 



The rapid development of organic chemistry has necessitated 

 a considerable amount of specialization, and the present work 

 deals with one of the specialized branches of the subject — that of 

 aromatic compounds. Although the use of aromatic substances 

 is as old as history itself, the scientific investigation of these 

 interesting bodies is of very recent date, and may, in fact, be 

 almost regarded as still in its infancy. The monograph under 

 review contains a systematic account of the present state of our 

 knowledge regarding aromatic compounds. Their chemical, 

 physical, and physiological properties are duly considered, and 

 special attention is given to the methods of isolating and preparing 

 them. A very full bibliography and list of German patents 

 relating to the subject are giveu in the introductory portion of 

 the book. 



Materialien der Stereochemie in Form von Jaliresbericliten. Bearbeitet 

 von C. A. Bischoef. Erster Band, 1894-1898 ; Zweiter 

 Band, 1890-1902. Braunschweig: F. Vieweg und Sohn. 

 1904. Vol. I. pp. cxxxvi + 840 ; Vol. II. pp. 1138. 



This monumental work should prove of exceptional value to the 

 many workers in the domain of stereo-chemistry, and may be 

 regarded as a sequel to the Haiulbuch der Stereochemie by C. A. 

 Bischolf and P. AV^alden. It covers the period 1894-1902, and 

 contains an account of the advances made in stereo-chemistry 

 during that period, in the form of abstracts of all the 

 more important memoirs published either in periodicals or in book 

 form. Such abstracts are accompanied by critical remarks, and 

 full references are given in each case in the form of footnotes. 



