82 



NATURE 



[March 27, igi, 



He shows amongst other things that variation in 

 the colour of certain areas, especially of the 

 ventral surface and of the tail, is discontinuous 

 and that not infrequently several individuals 

 differ from the ordinary run of rats in a particular 

 district by a combination of characters similar 

 to those used by systematists for discriminating 

 species or subspecies of Murida?. In the case of 

 Mus rattus it is tolerably evident that these in- 

 dividuals are members of a family party ; yet, as 

 Dr. Lloyd insists, if a similar series of individuals 

 were to emanate from a " field " species of Mus 

 and were to fall into the hands of a systematist, 

 they would probably be regarded as representa- 

 tives of an undescribed form and be named accord- 

 ingly ; and in that case they might for ever remain 

 the sole examples of the species or subspecies, 

 so-called. On the other hand, such a series might 

 by isolation in their locality give rise to a persistent 

 type. Dr. Lloyd discusses the question of the 

 origin of "species" from mutants, and expresses 

 the opinion that species have arisen in that way, 

 irrespective of natural selection ; and it seems that 

 he would lessen, to that extent at all events, the 

 belief in natural selection as a creative — one would 

 have preferred "guiding" or "fostering"- — 

 agency. He also supports his case by citing 

 Tower's records and statistics touching the 

 potato beetle. His views are clearly and modestly 

 put forward, and his book is worth careful atten- 

 tion, although the omission of an index, of a 

 table of contents, and even of headlines to the 

 chapters makes the reading more difficult than 

 it need have been. R. I. P. 



MET A LLURGICAL IND USTRIES. 



(1) A Text-book of Rami Metallurgical Practice. 

 Designed as a "Working Tool" and Practical 

 Guide for Metallurgists upon the Witwaters- 

 rand and other Similar Fields. By Ralph Stokes, 

 [as. E. Thomas, G. O. Smart, W. R. Dowling, 

 H. A. White, E. H. Johnson, W. A. Caldecott, 

 A. McA. Johnston, and C. O. Schmitt. Vol. ii. 

 Pp. xxii + 438. (London: C. Griffin and Co., 

 Ltd., 1912.) Price 21s. net. 



(2) The Technology of Iron Enamelling and 

 Tinning. Being Collected Papers. By J. Griin- 

 wald. Translated from the German by Dr. H. 

 H. Hodgson. Pp. viii+139. (London: C. 

 Griffin and Co., Ltd., 1912.) Price 6s. net. 



(3) Notes on Foundry Practice. By J. J. Morgan. 

 Pp. ix+108. (London: C. Griffin and Co., 

 Ltd., 1912.) Price 2s. hd. net. 



(1) r I "HE second volume of this work is by 



J_ Mr. C. O. Schmitt, and consists of two 



sections — "The Design and Construction of 



Reduction Plant" and "The Transport of 



NO. 2265, VOL. 91] 



Material " — the latter naturally being' the smaller, 

 occupying the last hundred pages of the book. 



The first section deals in a systematic manner 

 with the reduction plant used on the Rand, taking 

 in order the breaking plant, stamp mill, tube mill, 

 sand plant, slime plant, and precipitation plant, 

 and the author has covered this ground very 

 thoroughly, giving much useful information ; for 

 instance, when considering the design of a 

 reduction plant, the value of a volume diagram 

 and a flow sheet, in addition to the plan and 

 elevation of the plant, is pointed out. The 

 chapter on " Sorting and Breaking Plant " is good, 

 the subject being fully discussed, while under 

 "Crushing Plant" there is a comprehensive 

 description of the stamp mill found on the Rand, 

 all various parts of the battery being considered. 



The section on the modern foundations for 

 mortar boxes is particularly instructive and is 

 well illustrated. The " Nissen " stamp mill, which 

 has recently been run experimentally at the City 

 Deep, is briefly described. A most adequate 

 account of the Rand cyanide plant is given, and 

 it should be of use to all engaged in the cyaniding 

 of gold ores, for the cyanide process has proved 

 a most satisfactory means for the further treat- 

 ment of the Rand ore, with the result that there 

 have been great developments in the plant. An 

 important chapter on " Estimating " is included, 

 and the author of this volume rightly insists that a 

 detailed estimate of the cost of a plant which 

 has been designed is essential, and for this purpose 

 gives a set of useful schedules. 



In the second section of the book the plant for 

 the transport of material is fully described, the 

 methods of handling ore, dry sand, dry slime, 

 pulp and sand residue being given. This section 

 should be of general interest to mining and metal- 

 lurgical engineers, for the lack of labour on the 

 Rand has made mechanical handling of material 

 a necessity ; consequently a large number of 

 appliances is considered. 



The volume is copiously illustrated, and con- 

 tains many useful tables and valuable diagrams 

 as well as a good bibliography. 



The work is, as the authors claim, a "practical 

 book for practical men," and, although dealing 

 with the metallurgical practice upon the Wit- 

 watersrand, will be of value to those engaged on 

 goldfields where some of the conditions are 

 similar. The advanced student who is studying 

 the metallurgy of gold will find it a useful book, 

 lor it will broaden his outlook, give him an 

 insight into industrial problems, and will put 

 before him information gained by practical ex- 

 perience. The book can be thoroughly recom- 

 mended. 



