REVIEWS 155 



mended to those who are content with a concise matter-of-fact treatment of the 

 subject. The diagrams are numerous and exceedingly clear ; there is an ample 

 selection of problems (with answers) at the end of each chapter and a complete 

 course of practical work. The paper is good, but the binding over light for so 

 heavy a book. 



D. O. W. 



CHEMISTRY 



Theoretical and Applied Colloid Chemistry. By Dr. Wolfgang Ostwald. 

 Authorised Translation by Dr. Martin H. Fischer. [Pp. xv 4- 232, with 

 45 illustrations.] (New York : John Wiley & Sons. London : Chapman & 

 Hall, 1917. Price us. 6d. net.) 



This book contains a selection from a number of lectures delivered by the 

 author in America during the winter of 191 3-14. The object of these lectures is 

 essentially to claim for colloid chemistry the right to be regarded as an inde- 

 pendent science subject. There can be no question but that the plea is amply 

 justified, although colloid chemistry has not as yet attracted the attention which 

 it deserves. That this is Dr. Ostwald's view likewise is indicated by the sub-title 

 to the book, viz. "the world of neglected dimensions." 



Naturally in a brief survey of a more or less popular nature, the treatment can- 

 not be expected to be profound. Out of a wealth of material the author has made 

 an excellent choice. The most striking thing about these lectures is the experi- 

 mental illustration of many of the points discussed. It is indeed remarkable that 

 so much can be done within the limited range of a lecture demonstration. This 

 aspect of the work will be appreciated by all those who have occasion to lecture 

 upon the subject or who desire to bring colloids into a systematic course of practical 

 chemistry. 



The lectures reproduced are five in number. The first three deal with the 

 fundamental properties of the colloidal state, the concept of disperse systems, the 

 classification of colloids, and the properties of colloids as a function of the degree 

 of dispersion. The fourth lecture deals with "some scientific applications of 

 colloid chemistry," that is, with the application of the science of the colloid state 

 to other sciences, e.g. to physics, analytical chemistry, photochemistry, preparative 

 organic chemistry, mineralogy, geology, soil chemistry, agricultural chemistry, 

 biology, and medicine. The fifth lecture treats of a number of " technical applica- 

 tions of colloid chemistry." How vast the field is here will be gathered by simply 

 enumerating the more important technical operations, processes, and manufactures 

 in which colloid chemistry plays a significant role : the manufacture of lubricants, 

 use of straw infusions in brick-making, incandescent light filaments, coloured 

 glasses, ultramarine, photographic materials, inks, ceramics and hydraulic cements, 

 iron-carbon alloys, dyeing, tanning, cellulose industries, parchment manufacture, 

 mercerisation, artificial silk (viscose), celluloid, varnishes, bakelite, rubber coagula- 

 tion, vulcanisation, manufacture of soap, starch, glue, mucilages, food products 

 such as margarine, etc. This list, though by no means complete, covers the entire 

 round of chemical technology. No stronger argument could be urged for a fuller 

 realisation of the fundamental importance of colloid chemistry. 



The author has succeeded in presenting a well-balanced account of the possi- 

 bilities of colloid chemistry in an exceedingly readable and interesting form. 



W. C. McC. Lewis. 



