August i8, 1910J 



NATURE 



199 



after that of the Rand, for those who know both 

 deposits regard them as of the same origin, though 

 the iron ores of the West African banket still mainly 

 occur as magnetite. It seems difficult to regard the 

 West African banket as a modified placer, and the 

 South African as an ore due to infiltration. 



The feature in Prof. Beck's arrangement of ores 

 which seems most iinprobable is his reference of so 

 many metalliferous sandstones and conglomerates to 

 the epigenetic group. He includes there, for example, 

 the Katanga quartzite, which contains small nuggets 

 of gold and platinum. In fact, the only pre-Cainozoic 

 alluvial gold deposits which are included in the chapter 

 on detrital ores are those of the Cambrian of the Black 

 Hills of Dakota, a few occurrences of no economic 

 value in the Carboniferous rocks of Australia, Nova 

 Scotia, and France, and in the Mesozoic of California, 

 New Zealand, and Saxony. Alluvial gold must have 

 been deposited in pre-Cainozoic times, but whenever 

 ancient gravels are of much economic value their gold 

 is attributed to infiltration. While in some cases 

 Prof. Beck may be disposed to underrate the extent 

 of ancient alluvial ores, he includes the tin deposits 

 of Mt. Bischoff in Tasmania as alluvial, having appa- 

 rently overlooked a short note upon that mine, ex- 

 plaining its tin-bearing sands as decomposed gossan 

 in which a pseudo-stratification has been produced bj' 

 the settling of the decaying rock. 



Prof. Beck's work shows remarkably thorough ac- 

 quaintance with recent literature on economic geology, 

 and his statement of rival hypotheses is always given 

 with scrupulous fairness. This greatly enlarged 

 edition will become even more indispensable as a work 

 of reference than its predecessors, and is worthy of 

 the high traditions of the Freiburg Mining School. 



J. W. G. 



THE SUGAR-CASE J.VD ITS PRODUCTS. 

 The Manitjacturc of Cane Sugar. By Llewellyn Jones 

 and F. I. Scard. Pp. xix + 454. (London: Edward 

 .Stanford, 1909.) Price 12.';. 6d. net. 



A NOTEWORTHY feature in tropical agriculture 

 is the new lease of life taken recently by the 

 cane-sugar industry. A few years ago it appeared not 

 improbable, to say the least, that the sugar-cane was 

 doomed to be forced into a position permanently infe- 

 rior to that of the beet as a source of the world's supply 

 of sugar. Originallv possessed of a practical mono- 

 poly, the cane had lost so much ground that in the 

 opening years of this century the beet supplied about 

 two-thirds of the sugar which came into the world's 

 markets. It is true that a great deal of cane- 

 sugar is consumed in countries where it is 

 produced and escapes record; so far as the world's 

 commerce was concerned beet was the chief contributor. 

 Within, however, the last five years, the output of 

 cane-sugar has markedly increased, whilst that of beet 

 has slightly diminished, and a little more than one- 

 half of the sugar of commerce is now derived from 

 the sugar-cane. 



This period of activity in the industrv has been 

 marked by the issue of various books. One of the 

 most useful is that now under review. The authors 

 NO. 2129, VOL. 84] 



have wide practical experience of sugar-making, as 

 engineer and chemist respectively ; with the aid of 

 numerous illustrations they present the results of their 

 experience in an exceedinglv simple manner. 



.V marked feature of the book is the explanation of 

 practical matters in clear, non-technical language, and 

 a reader with no special engineering knowledge and 

 no experience of sugar-making should easily under- 

 stand and be able to follow the whole chain of pro- 

 cesses by which the ripe sugar-cane is converted into 

 sugar and the various by-products. 



No pretence is made to deal with cultivation. There 

 is in chapter i. an illustrated account of the structure 

 of the cane (the references on pp. 3 and 4 to the 

 figures are not accurate), and notes on the chief 

 varieties, diseases, chemical composition, &c. ; but 

 the subject-matter proper of the book opens with 

 crushing, in the next chapter. Whilst the novice will 

 read this easilv, the mature planter will find much 

 worthy of consideration, as, for example, in the excel, 

 lent presentment of the pros and cons of improved 

 methods of extraction. In dealing w'ith the boiling 

 or concentration, the evolution of the modern vacuum 

 pan, capable of yielding 40 tons of sugar at a single 

 operation, is traced from the simple open pan still 

 in use in many parts of the w-orld. Equally here, 

 whether dealing with the simplest or the most com- 

 plicated processes, the authors have contrived to pre- 

 serve a conspicuous^ clear and direct style. 



The volume is one w'hich should be of great value 

 to non-technical readers who wish to obtain informa- 

 tion regarding one of the best-organised and most 

 scientific of the great industries of the tropics. The 

 practical sugar-maker will appreciate the exposition 

 of the theory underlying various processes, the clear 

 description of methods, and also doubtless derive 

 assistance from the useful practical hints with which 

 the book abounds. W. G. F. 



THE PSYCHOLOGY OF THE WILL. 

 Ueber den Willeiisakt :ind das Temperament : einc 

 experimentellc Untersuchitng. By Prof. Narziss 

 .•\ch. Pp. xii4-324. (Leipzig: Quelle and Meyer, 

 1910.) Price 6.50 marks. 



I'^O the layman an act of volition is one of those 

 obvious things, such as gravity or growth, 

 which present no difficulty and suggest no problem. 

 Their mechanism is so smooth in its working that 

 the mind never dreams of the presence of a mystery. 

 Add to which the fact that it is impossible to go 

 through the process of willing and at the same time 

 to contemplate and observe the process. Yet at least 

 one difficulty has been noted by the crudest philosophy 

 for ages past — the' power of choice, the so-called 

 freedom of the will. This, however, as Prof. Ach 

 observes, is a function not of the will but of reason. 

 He also well insists that the judgment " 1 can do that 

 which I will," has two distinct meanings, which have 

 often been confused. The one meaning is positive, 

 '■ I have the capacity to carry out w-hat I will " ; 

 "can" being equivalent to posse, pouvoir, vermogcn. 

 The other is negative, " It is my wish to do what I 

 will." Psvchologists are onlv too well aware that "In 



