May 7, 1896] 



NA TURE 



cessful performance of any given separation. The analysis 

 of these conditions is one of the most admirable features 

 of the book, complete explanations bein^i given in all cases 

 where the theory of the reactions is known (as in the 

 separation of nickel and cobalt) ; conditions found to be 

 necessar)' by experience, for which no theoretical reason 

 can be given, are definitely stated to be empirical. One 

 point emphasised here, to which no reference is made in 

 our current text-books, has reference to the composition 

 of the metallic sulphides obtained in the wet way. It is 

 pointed out that the anhydrous sulpliides as obtained in 

 ([uantitative analysis differ considerably in their proper- 

 ties (colour, rate of oxidation) from the precipitates 

 obtained in the ordinary course of qualitative work, and 

 these differences of behaviour correspond to differences 

 in composition. Thus the precipitates obtained with 

 hydrogen and ammonium sulphides are in many cases 

 hydrated sulphides (R(SH)(OH) rather than RS). The 

 anhydrous sulphides are occasionally formed in solution, 

 and might give rise to confusion in certain cases. Thus, 

 whilst the ordinarj- hydrated sulphide of manganese is 

 yellow or flesh-coloured, in presence of an excess of 

 ammonia and ammonium sulphide a green precipitate of 

 anhydrous manganous sulphide is sometimes formed, 

 especially from hot solutions. Again, the black precipitate 

 obtained by treating cupric solutions with hydrogen 

 sulphide is CU4S3, and not CuS, as usually stated, the 

 latter substance, according to Prof. Menschutkin, being 

 unknown. 



The analytical properties of the rarer metals are briefly 

 treated in separate chapters. It would have added much 

 to the scientific value of the book if this artificial distinc- 

 tion between ordinary and so-called "rare" metals could 

 liave been dispensed with. The present stereotyped 

 mode of treatment is the chief cause of the want of 

 knowledge by the average student of the properties and 

 reactions of nretals such as gold, platinum, cerium, 

 uranium, and others that can only be conventionally con- 

 sidered as "rare.' 



The second half of the book deals with quantitative 

 analysis. The descriptions are concise and the methods 

 well chosen, but are hardly sufficiently detailed for the 

 Ijeginner, 



OUR BOOK SHELF. 

 Gruiuiriss der Krystallogniphie fur Sttidireiide iiiid ztciii 



Selbstunterricht. By Gottlob Linck. Pp. vi + 252, 



482 figures, and 2 plates. (Jena : Gustav Fischer, 



1896.^ 

 This book makes no pretence at supplanting such well- 

 known works as those of Groth and Liebisch, but is 

 intended for the less advanced student, and more 

 especially for the chemist, to whom the necessity of 

 some knowledge of crystallography is becoming increas- 

 ingly felt. Except in one important particular, little 

 attempt is made to break away from old methods of 

 treatment. The thirty-two classes of symmetry are not 

 treated as independent, but crystal symmetry is distri- 

 buted in the usual way into the six systems, and under 

 each system are described the holohedral, hemihedral 

 and tetartohedral forms. Both the Naumann and the 

 Millcrian symbols for the faces are used, but greater 

 prominence is given to the former. 



An important innovation, howe\er, is made in the 

 chapter on the optical characters of crystals. Here, we 



NO. 1384. VOL. 54] 



are glad to see, the author has followed the example 

 of Prof Groth and adopted the purely geometrical treat- 

 ment involving the use of the " Optical Indicatri.x," as 

 devised by Mr. Fletcher. 



The book is fairly evenly divided between the two 

 sections dealing respectively with the geometrical and 

 the physical characters of crystals, about a hundred 

 pages being^ devoted to each. As it is not written for 

 the advanced student, the subject of the calculation and 

 graphic representation of crystals is not touched upon. 



The book appears to be well adapted to the purpose 

 for which it is intended. G. T. P. 



Cyanide Processes. By E. B. Wilson, E.M. Pp. 116 

 (New York : John Wiley and Sons. London : Chap- 

 man and Hall, Ltd., 1896.) 

 It is difficult to say with what object this little book has 

 been written, and so it would perhaps be rash to assert 

 that its object has not been attained. It is, at any rate, 

 to be regretted that -Mr. Wilson's work ever saw the 

 light, as it is distinctly inferior to each of the half-dozen 

 accounts which have already appeared of the cyanide 

 process for the extraction of gold from its ores, and can 

 only mislead and confuse those who expect to learn 

 something from it. It is evident, from his own statements 

 in the preface and elsewhere, that the author has derived 

 much of his acquaintance with the subject from Patent 

 Office literature, although he also claims to have read 

 extracts from technical journals and other periodicals. 

 He has not touched on mechanical details, but has con- 

 fined himself to expounding the chemical principles of 

 the process, which he appears to understand very imper- 

 fectly. The book is full of mistakes, such, for example, 

 as that " the standard solution of cyanide contains from 

 o'5 to Tj per cent.," and that mercury oxidises quickly in 

 the air at ordinary temperatures. On p. 74 it is stated 

 that " the gold positive dissolves to the cyanide solution 

 negative, with the result that the gold cyanide solution 

 is positive. . . . Whether this electrolyte becomes con- 

 verted into an electrode by absorbing the gold we are 

 unable to say, but when they become ' cations ' the gold 

 is in the metallic state and the potassium cyanide is im- 

 mediately set free." The book is well supplied with 

 such statements as this. T. K. Rose. 



The Treatment pf Phthisis. By Dr. Arthur Ransome, 

 M.A., F.R.S. Pp. viii -|- 237- (London : Smith, Elder, 

 and Co., 1896.) 

 Medical men will be grateful for this treatise on the 

 treatment of phthisical patients. The first part of the 

 work comprises a general statement on the etiology 

 pathology of phthisis, and the limits of infection; while 

 the second part deals with the special and medicinal 

 treatment of the malady. The contents are largely con- 

 fined to descriptions of methods of treatment which have 

 been personally used by the author, and results which 

 have come under his own experience ; but they, neverthe- 

 less, constitute a broad account of the nature arid means 

 of combating phthisis, and one which will give physicians 

 brighter views as to the possibility of cure in the disease. 

 A Text-book of Applied Mechanics. Vol.1. By Alexander 

 Jamieson, M.I.'C.E., Professor of Electric Engineering 

 in the Glasgow and West of Scotland Technical Col- 

 lege, &c. Pp. 416. (London : Charles Griffin and Co., 



1895-) 

 The influence of Rankme is apparent here ; the ground 

 covered is much the same as in Rankine's " .'Applied 

 Mechanics," but the treatment is more elementary, and 

 the illustrative e.xercises and diagrams of a modern 

 character. 



If our writers of elementary school books on Mechanics, 

 all copied from each other and almost exactly alike, could 

 be persuaded to lift their eyes from their own pages and 

 look elsewhere for novelty and reality, they would derive 

 some profit from a treatise such as this. G. 



