y^oth'es respectiwf JSeio Books. 379 



systems devised by Popoft', Mnrcoui, Lodge aud Muirhe:id, 13 rami, 

 and Slaby aud Arco. Part IV. deals with systems based on photo- 

 electric effects. 



The book is one which slionld prove of interest to the gener;il 

 reader as well as the serious worker in science 



L'e. 



Mechanicfty Molecular Physics and Heat : A Twelve Weehs'' College 

 Course. By R. A. Millika?^, Ph. I)., Assistant Professor of 

 rhysics in the University of Chicago. Chicago : Scott, Foresman 

 and Co. 1902. Pp. vii+242. 



Althougk there are numerous laboratory manuals of physics in 

 existence, we welcome this additioji to the literature of the subject, 

 both because it will render English teachers familiar with the 

 methods employed at the L^niversity of Chicago, and also on 

 account of its being unlike the ordinary laboratory manual. This 

 latter it is, indeed, nor. wholly intended to be, as the author informs 

 us in his preface. One of the chief characteristics of the book is 

 the large amount of space devoted to the elucidation of \\iQ prin- 

 ciples involved in the experiments selected. The number of experi- 

 ments dealt with is not large, but they are all typical of important 

 classes of accurate measurements, and the apparatus employed, 

 most uf which is of modern design, is such as to admit of a high 

 degree of accuracy. The illustrations and descriptions of the 

 apparatus should prove of great interest to teachers in England, 

 and the book as a whole reaches the highest standard of excellence. 



Der SticTcstoff unci seine Wichtigsten Verhindungen. Von Dr. 



Leopold ISpiegel, Pnvatdocent an der Universitcit Berlin. Mit 



Eingedruckten Abbildungen. Braunschweig : E. Yieweg und 

 Sohn. 1903. Pp. xii-F912. 



This elaborate and comprehensive treatise on nitrogen and its com- 

 pounds will form an extremely useful book of reference for chemists, 

 chemical physicists, and physiologists. Important as is the part 

 played by carbon in the chemistry of living tissues, nitrogen is 

 hardly less important. The author has compiled a treatise in which 

 all but the most recent researches relating to nitrogen compounds 

 are dealt with, and has supplied numerous references to original 

 papers. A mere glance at the long list of references occurring at the 

 foot of almost every page gives some idea of the enormous amount of 

 labour vvhich must have been bestowed on the preparation of the 

 book. It is a most thorough and exhaustive account of the subject. 

 As regards the general plan of the book, the author seems to 

 have adopted the principle of proceeding from the less to the more 

 complicated portions of ths subject. After a full account of the 

 occurrence, properties, and preparation of nitrogen, he deals with 

 the halogen compounds, the oxides, the sulphur and hydrogen 

 compounds, the nitrides of the metals, phosphorus and arsenic 



