May 19, 1904] 



NA TURE 



51 



assumed as a basis of method, but in his preface 

 M. Moissan says : — 



" Nous apportons, sur ce sujet, des id^es eclectiques, 

 et la raison, ^clair^e par Texperience, sera toujours 

 notre seul guide." 



The geological and mineralogical sources of sub- 

 stances are considered, but the details of physical and 

 analytical chemistry are not touched. Industrial 

 operations are sonietimes chosen to illustrate chemical 

 change, and, where thought desirable, the prices and 

 tables of production of different countries are intro- 

 duced. The work is primarily intended for those 

 engaged in research, in industry, and in teaching. 

 Among the thirty-two contributors may be mentioned 

 the names of Charpy, ittard, Le Chatelier, Lemoine, 

 Sabatier, and Vogt, besides many others of good 

 reputation. 



The introduction by the editor gives a historical 

 sketch of the classification of the elements. In the 

 present state of our knowledge of elementary bodies 

 it is interesting to meet with the unprejudiced words 

 of Lavoisier : — 



" If, by the word element, we mean the simple and 

 indivisible molecules of which bodies are composed, it 

 is probable that we do not know them ; but if, on the 

 other hand, we apply the name element or principle 

 to the last term at which chemical analysis arrives, 

 all substances which have not hitherto been decom- 

 posed are for us elements." 



The bearing of spectrum analysis on the question 

 of the unitv of matter is. briefly touched on, and 

 Moissan says that in his own high temperature work 

 no sign of transmutation has ever been observed. He 

 inclines, however, to the supposition of the unity of 

 matter, and in alluding to the recent work connected 

 with radio-activity, he believes that " we are witness- 

 ing the dawn of inorganic chemistry, a subject not 

 long ago regarded as exhausted." 



Various attempts at classification are next con- 

 sidered, but not even the periodic table is adopted. 

 The reviewer cannot agree that the method followed 

 presents anv adv-antage whatever. The first family 

 comprises hydrogen and helium, and the reason given 

 for this curious collocation of elements is that helium 

 is not well known ! Carbon is separated from silicon, 

 because the latter element forms no large number of 

 " organic " compounds, and because the halides of 

 silicon, like those of titanium and zirconium, are de- 

 composed by water. While in most groups the element 

 of lowest atomic -weight is discussed first, caesium 

 begins the metals of the alkali group, because of its 

 chemical activity ; for the same reason the nitrogen 

 group should begin with phosphorus. The final state- 

 ment that the author thought it better to group the 

 elements in accordance with their known properties 

 rather than to give them to the reader in the disorder 

 of alphabetical order seems hardly a happy way of 

 determining which method of classification is the best, 

 seeing that no particular properties are chosen, the 

 criterion of resemblance sometimes being the appear- 

 ance of the element, sometimes its melting-point, some- 

 NO. 1 803, VOL. 70] 



times the stability of its salts in presence of water, 

 and sometimes none of these, as where cobalt is placed 

 in the same group as uranium, and lead and tin are 

 separated from each other. 



The result is, that without an index, w-hich has not 

 3'et appeared in any one of the published parts, it is 

 an almost hopeless task to find any desired compound. 

 Gmelin's plan, perhaps, may serve as guide, that is, 

 to find out the elements which have been treated of 

 already, and to take the last in the formula of the 

 compound as an index. But this leads to such an 

 anomaly as having to look up bismuth thiocarbonate 

 under " carbon," while potassium thiocarbonate coines 

 under the heading " potassium." The amido- 

 derivatives, too, are to be found after the salts from 

 which they are prepared, and do not form a group by 

 themselves, similar as they all are to each other. 



Subject to these criticisms, however, the work is 

 very complete, and is a most valuable compilation. It 

 is unfortunately not free from omissions ; for example, 

 in discussing the determinations of the density of 

 hydrogen, the work of Lord Rayleigh has been over- 

 looked. Again, it is stated on the authority of Lunge 

 (1879) that the greatest amount of chlorine in the world 

 is made at the St. Rollox Works in Glasgow, a state- 

 ment which is now unfortunately inaccurate. The 

 spelling of proper names, also, leaves room for correc- 

 tion ; Brareton-Bakor, Tadeusz Estreicher, and Stass 

 are among those which have caught the reviewer's 

 eye. But, as before remarked, the index of literature 

 is very large, and the number of facts given is greater 

 than what is ordinarily to be found in a text-book, 

 while the information is generally up to date, and these 

 are advantages which cannot be overloolied. 



ELECTRIC TRAMS. 

 Electric Traction. By J. H. Rider. Pp. xvi + 453. 

 (London : Whittaker and Co., 1903.) 



THE name of the author and his position as chief 

 electrical engineer to the London County 

 Council Tramways are sufficient to recommend this 

 book to anyone interested in electric traction. Nor 

 do we think that anyone who takes it up in the hope 

 of gleaning some useful or suggestive information is 

 likely to put it down with the slightest feeling of dis- 

 appointment. The style is terse, but eminently read- 

 able; the opinions expressed by the author are often, 

 no doubt, open to argument, but they have the great 

 merit of conveying the impression that they are the 

 opinions of a man who knows practically all that there 

 is to be known about his subject, and who does not 

 hesitate to state his own convictions, whether they are 

 likely to be in agreement with those of other people 

 or not. For example, we may refer to the little out- 

 burst of evident irritation at the need for the objection- 

 able but compulsory guard-wires. These, the author 

 holds, " do not strike at the root of the matter, which 

 is to proliibit entirely uninsulated wires of any kind 

 crossing above the trolley wires." Here speaks not 

 the expert, but the tramway engineer; perhaps if fate 

 had destined Mr. Rider to be a telegraph engineer, we 



