170 SCIENCE PROGRESS 



then be organised, but merely asserts that the existence of property and the 

 struggle for wealth cause the conflict of classes, but that when the economic 

 question disappears, psychic adaptation will be fully realised and man will 

 reproduce the harmony of the natural laws. 



It may be inferred from internal evidence that the translators of Dr. Lluria's 

 book, of whom Mr. Lambert, owing to the death of Miss Challice, is chiefly 

 responsible, were qualified for the task by a knowledge of Spanish rather than by 

 a knowledge of biology. They employ throughout the word neurona instead of the 

 English term neuron : they refer to the zoospore of the Ascaris instead of its 

 spermatozoon; the name of the species of newt Pleurodeles waltlii is perverted 

 into the Pleuro of the Walti. On the whole the general impression left by 

 the book in its English version is that both author and translators have attempted 

 a task beyond their powers. 



J. T. Cunningham. 



Metallography, By Cecil H. Desch, D.Sc, Ph.D. [Pp. .xii + 429.] (London : 

 Longmans, Green & Co., 1910. Price ()s.) 



The valuable series, Text-Books of Physical C/ieinistty, edited by Sir William 

 Ramsay, has been enriched by this volume on metallography. The study of 

 metals and alloys by thermal and microscopical methods has received serious 

 attention during the last twenty years, and has now developed into an important 

 science. The laws and doctrines of physical chemistry form the basis on which 

 investigators have constructed their theories and made additions to our know- 

 ledge ; therefore a book devoted to the study of the structures and properties 

 •of metals and alloys is justly entitled to a place in this series. 



The preparation of a text-book on metallography is not an easy matter, the 

 subject having two sides which need equal attention ; for particulars of the methods 

 of investigation require as much explanation as the physico-chemical phenomena, 

 and the difficulty lies in selecting the place for the introduction of the former. In 

 this work Dr. Desch has combined the theoretical considerations with the 

 practical details of pyrometry and micrography in quite a satisfactory manner. 

 The theory of mixtures is excellently explained ; thermal equilibrium being gone 

 into very clearly and completely. The chapter dealing with ternary systems 

 (Chapter IV.) will be found particularly valuable, for such systems are assuming 

 greater importance, since with industrial alloys advances will undoubtedly be 

 made in the direction of a combination of three or more metals, and as a rule, 

 this branch of the subject is only briefly described in text-books on physical 

 chemistry. 



Following the four chapters on "The Diagram of Thermal Equilibrium" are 

 •others devoted to a thoroughly practical description and sane criticism of 

 instruments and methods used in metallographic work. The chapter on " Practical 

 Pyrometry " finishes with some necessary and sound remarks on pyrometric 

 investigations, among which are the following : " Determinations of freezing-point 

 curves, if undertaken at all, should be perforn\ed with the utmost available 

 accuracy. The knowledge of alloys has now reached a point at which there is no 

 need for more rough preliminary surveys, especially as the points which are of 

 the greatest theoretical importance are precisely those which are most likely to be 

 •overlooked in an incomplete investigation. . . . Metallography, more than most 

 branches of physical chemistry, has suffered in the past from the accumulation of 



