Reviews — J. Allen Hoive — Kaolin, China-clay, etc. 371 



REVIEWS. 



I. — Mcseum of Pkactical Geology. 



A Handbook to the Collection of Kaolin, China-clay, and China- 

 stone in the Museum of Practical Geology, Jeemyn Steekt, 

 London, S.W. By J. Allen Howe, B.Sc, F.G.S., Curator. With 

 an Appendix by Allan B. Dick. pp. viii, 271, pis. ix. London: 

 Darling & Son, Ltd., 1914. Price 3s. 6d. 



IT is a curious technological fact that our knowledge of the 

 constitution of many materials which owing to their useful 

 properties have acquired an extended application is decidedly 

 limited. Bleaching powder and Portland cement might be cited as 

 examples among inorganic materials, and india-rubber among organic 

 substances. A large amount of investigation has been directed towards 

 elucidating the constitution of bleaching powder, the chemical changes 

 that occur during the setting and hardening of cement, and to the 

 isolation of the various constituents which collectively form india- 

 rubber, but it can hardly be said that the last word has been uttered 

 on these problems. 



The handbook now under review contains ample evidence that we 

 do not fully comprehend either the mode of origin or the constitution 

 of the essential raw material of what is credited with being the most 

 ancient of the arts. Though nominally a handbook to the collection 

 of Kaolin, China-clay, and China-stone in the Museum of Practical 

 Geology, the volume would be far more accurately described as 

 a valuable guide to the study of Clays, and contains information of 

 service not only to the geologist and clay-worker but to many other 

 classes of inquirers. 



The introduction and chapters iv and v give a brief account of the 

 nature and uses of china-clay and china-stone. The second chapter, 

 describing the discovery, development, and method of mining the 

 famous deposits of Cornwall and Devon, contains matter interesting 

 not only to the general reader but also to those more directly 

 connected with the industry. The inclusion of this chapter is 

 particularly serviceable, since it covers the ground of A Treatise on 

 China Clay, written by David Cock more than thirty years ago, 

 which, unfortunately, is out of print and scarce. Chapter iii has 

 given to English readers an account of the distribution of kaolins 

 all over the world, which certainly has never been easily accessible 

 hitherto. Chapter vi affords a very fairly complete survey of our 

 present knowledge of some of the physical characters and chemical 

 constitution of kaolinite and several minerals allied to it. 



Chapter vii, on the origin of kaolin, will naturally appeal most 

 strongly to the geologist, and certainly affords him an excellent and 

 critical examination of the various theories that have been advanced 

 to account for the existence of china-clay rock. This fascinating 

 problem is by no means as simple as it might at first appear. The 

 simple explanation, found in all textbooks on geology, of the process 



