330 SCIENCE PROGRESS 



The illustrations are clear and concise and will be recognised by many who 

 are familiar with the subject : at the same time one cannot altogether agree with 

 Dr. Cain when he says (p. vi) that it is " superfluous to reproduce figures of ordinary 

 plant . . . which are illustrated in the advertisement columns of periodicals." 

 It would undoubtedly be of great interest, particularly to the student, to see 

 photographs or diagrams of the actual standardised plant made by various 

 manufacturers, and which cannot always be found in the advertisement columns 

 just when wanted ; these, however, are minor points. 



The book should prove of great value as a time saver at the present moment, 

 and one may look forward with confidence to seeing it run through many editions. 



F. A. Mason. 



Chemical Combination among Metals. By Dr. Michele Giua, Professor of 

 Chemistry in the Royal University of Sassari, and Dr. Clara Giua- 

 Lollini ; translated by Gilbert W. Robinson, University College, 

 Bangor. [Pp. xiv + 341, with 207 figures in the text.] (London : 

 J. and A. Churchill, 1918. Price 21;. net.) 



Until recently, the ability of the metallic elements to combine with each other 

 was hardly considered seriously, and, indeed, their inability to do so was looked 

 upon as one of the most obvious characteristics of this class. 



Since the beginning of the present century, however, many advances, both on 

 the scientific and technical sides of the question, have been made, largely due to 

 the introduction of Tammann's thermal method, and, above all, to the application 

 of W. Gibbs' Phase Rule to the examination of metallic systems. 



The present volume, translated from the Italian original, which was awarded 

 the prize of the Cagnola Foundation by the Royal Lombardy Institute of Science 

 and Literature, affords a useful summary of the present state of our knowledge of 

 the subject. 



Chapters are given on equilibrium diagrams, thermal analysis, and the nature 

 and physical properties of inter-metallic compounds, the latter part of the book 

 being devoted to the individual homopolar and heteropolar compounds, many 

 useful diagrams illustrative of their properties being included. 



In view of the ever-increasing demand for new alloys for special purposes, this 

 book should prove to be of considerable value to those interested as showing, on 

 the one hand, what is already known, and indicating, on the other, possible new 

 lines of research. 



F. A. M. 



AGRICULTURE 



The Potato. By Arthur W. Gilbert, Ph.D., Professor of Plant Breeding, 

 New York State College of Agriculture at Cornell University. Assisted by 

 Mortier F. Barrus, Ph.D., Professor of Plant Pathology, New York State 

 College of Agriculture at Cornell University, and Daniel Dean, formerly 

 President of the New York State Potato Association. (Rural Science Series.) 

 [Pp. xii + 318, with 29 text-figures and 16 plates.] (New York: The 

 Macmillan Company, 1917. Price $1.50.) 



In the decade immediately preceding the war the potato was the world's largest 

 crop, and the effect of the food shortage produced by the war has been, as every 

 one is aware, to increase the importance of the potato, for, as is pointed out on the 

 first page of this book, " a greater weight of potatoes can be produced to a unit 



