3^). 



NATURE 



[September 8, 192 1 



ous coagulants and found acetic acid the most 

 suitable, the planting- industry eventually settled 

 down to the production of rubber of two types : 

 (i) washed coagulum, air-dried in the form com- 

 monly known as pale crepe ; and (2) surface- 

 washed sheet rubber dried in a smoke-house, the 

 so-called smoked sheet. Faced with these alterna- 

 tives, the manufacturers were still unwilling or 

 possibly unable to give the planter advice. Some 

 could use only sheet, others only cr^pe, yet from 

 both varieties very good motor tyres were made 

 and exhibited at the last rubber exhibition in 1914. 

 Any lack of information or advice from the manu- 

 facturers was amply compensated for by the 

 brokers and dealers. These gentlemen supplied 

 abundant criticisms of surface defects and other 

 minor details which have kept planters busy in 

 their factories and the local chemists in their 

 laboratories. 



In spite, however, of the time thus occupied, a 

 very considerable amount of scientific work deal- 

 ing with vulcanisation and the chemical and physi- 

 cal properties of rubber has been accomplished. 

 Prof. Whitby's book is a significant record of the 

 research work carried out on behalf of the plant- 

 ing community. With one or two exceptions, 

 our whole knowledge of the subjects treated rests 

 on the results of such researches. The remainder 

 of the book is concerned with the more purely 

 physical researches on the properties of vulcanised 

 rubber, for which we are indebted to the academic 

 physicists. This is a novel feature, and comprises 

 the first summary of the subject to be published. 



The technical aspect of rubber vulcanisation is 

 dealt with by the author in chap. 16. This is 

 perhaps the one chapter in the book which might 

 with advantage have been extended. It is true 

 that our knowledge in this direction is very 

 limited, for reasons already given, but the sub- 

 ject-matter does not include references to some 

 of the more recently published work. It might 

 with advantage have included an account of work 

 on organic and inorganic " accelerators," or 

 vulcanisation catalysts, and cognate subjects, with 

 particular reference to the fast-curing types of 

 plantation rubber in which the " natural accelera- 

 tors " take the place of the synthetic products 

 which would otherwise have been added by the 

 manufacturer. In this chapter, and indeed 

 throughout the book, the author has suc- 

 ceeded in preserving a detached and impartial 

 attitude when commenting on published results. 

 He has examined each thesis with care, and ex- 

 pressed his reasoned conclusions with moderation. 



The book contains a mass of information — in 

 fact, practically everything of importance that is 

 NO. 2706, VOL. 108] 



known on the subject — and while it is put together 

 systematically, it is no mere catalogue of facts 

 and theories. One occasionally meets with an 

 awkwardly worded sentence, but the meaning is 

 usually clear. A few instances taken at random 

 may be quoted. The word " breaking length " 

 appears to be used in the sense of final length, 

 whereas in other industries the expression has a 

 totally different meaning. Hollow mixing rollers 

 are usually pi-ovided with a single inlet or outlet, 

 which serves for either steam or water ; thev are 

 not provided internally with separate pipes for 

 each. The "thickness " of a ring referred to on 

 p. 288 is more correctly described as the width, 

 for if the ring is considered as a short tube, the 

 thickness would correspond to the thickness of 

 the wall of the tube. 



The author has dealt with a subject which is in 

 a state of rapid development, and considerable 

 skill must have been required to incorporate the 

 new material appearing during compilation. This 

 may account in part for the frequency of footnotes 

 of considerable length, some of which might with 

 advantage have been included in the text. We 

 have noticed a few inaccuracies and misprints ; for 

 instance, "clippings," "modal," " centrifiguat- 

 ing," "Euphoria," and " laticometer. " The 

 book is provided throughout with copious refer- 

 ences and an excellent bibliography which will be 

 found of great value. H. P. S. 



Aeronautics. 



(i) Aviation: Theoretico-Practical Text-hook for 

 Students. By B. M. Carmina. Pp. ix+172. 

 (New York : The Macmillan Co. ; London : 

 Macmillan and Co., Ltd., 1919.) us. net. 



(2) The Theory and Practice of Aeroplane Design. 

 By S. T. G. Andrews and S. F. Benson. (The 

 Directly-Useful Technical Series.) Pp. xii -1-454. 

 (London: Chapman and Hall, Ltd., 1920.) 

 155. 6d. net. 



(3) Aeroplane Structures. By A. J. S. Pippard 

 and Capt. J. L. Pritchard. With an introduc-" 

 tion by L. Bairstow. Pp. xiii-F 359-1-21 plates. 

 (London: Longmans, Green, and Co., 1919.) 

 215. net. 



(i) '"T^HERE is certainly room for a good 

 X elementary treatise on the aeroplane, 

 written for young students who have only a 

 moderate equipment of mathematical knowledge, 

 and whose acquaintance with mechanics is limited 

 to the fundamental principles and their immediate 

 applications. Mr. Carmina had an obvious gap 

 to fill, but one must unhesitatingly declare that 

 he has failed to take advantage of the opportunity) 





