REVIEWS 157 



The chapters deaUng with the effect of alkah on physical conditions and the 

 movements of salts through the soil are well suited to their purpose. 



The book can be recommended, as an account, by a prominent worker in 

 the subject, both of the present position of the alkali problem, and of practical 

 methods of coping with it. B A Keen 



Plantation Rubber and the Testing of Rubber. By G. Stafford Whitby, 

 Ph.D., M.Sc, A.R.C.Sc. [Pp. xviii + 559, with plates and diagrams.] 

 (London : Longmans, Green & Co. Price 28s. net.) 



When, in the early seventies, the first experiments were made on the cultiva- 

 tion of the wild Brazilian rubber trees on plantations in Ceylon, the promoters 

 of the scheme can have little suspected that their enterprise would be so 

 successful as to displace, within a space of forty odd years, the main source 

 of natural rubber from the tropical forests of South America to the plantations 

 of the old world. While so recently as 1906 the production of plantation rubber 

 only amounted to less than i per cent, of the world's total output from Brazil 

 and elsewhere, the percentage had increased to 79'5 in 1917. During this short 

 period the production of Brazilian wild rubber had remained almost steady, 

 while that of wild rubber from other sources had fallen to less than half its 

 original value, and the enormously increased demand for rubber was therefore 

 met almost entirely from the plantations of the Malay Peninsula, Sumatra, 

 Java, and Ceylon. The circumstances of the production of the crude rubber 

 from the two sources being so entirely different, it is not surprising that the 

 methods of treating the material in the two cases are different ; the scientific 

 methods of production and control practised in the plantations cannot, of 

 course, be applied in the case of rubber collected by natives working in more or 

 less inaccessible regions of the forests on the Amazon. As the title states 

 the present volume is concerned with the plantation industry, and a perusal of 

 the book clearly demonstrates the complexity of the problems involved in 

 standardising the methods of production and testing. The book is divided 

 into two parts, devoted respectively to " The Preparation of Plantation 

 Rubber " and " The Testing of Rubber." In the first part are set forth the 

 very large number of factors which enter into the problem of obtaining a 

 uniform material. Rubber is such a sensitive material that at all stages of 

 its production circumstances may arise which will influence its physical 

 properties and may increase the difficulties of its subsequent treatment ; to 

 mention only one example, there is the tendency of the latex to coagulate to 

 "lumps" before it reaches the coagulating station, which means that pre- 

 cautions have to be adopted to check this objectionable property. 



The second part of the book deals with a number of investigations made by 

 physicists and others into the physical properties of rubber and the immensely 

 important subject of vulcanisation and the various factors which influence 

 the rate of vulcanisation, or " cure " as it is technically known. In the opinion 

 of the author some of the physical properties of rubber have not yet received 

 their due amount of exact experimental study. The book contains a great 

 deal of information, and forms a valuable addition to the gradually increasing 

 number of volumes issued under the general heading of Monographs in Indus- 

 trial Chemistry, 



P. H. 

 GEOLOGY 



The Nomenclature of Petrology. By Arthur Holmes. [Pp. 284.] (Lon- 

 don : Thomas Murby & Co. Price 12s. 6d. net.) 



Probably few sciences are burdened with a nomenclature so unsystematic 

 and unscientific as that of petrology. Rock names have been based on 

 mineral characters, texture, mode of formation, colour, locality, and numerous 



