<>lQO 



NATURE 



[November 24, 1910 



five of the languages under one alphabet, and the 

 Russian under another. The general arrangement, 

 .and the ground covered by each volume, leave nothing 

 • to be desired, and this dictionary will prove invaluable 

 to all those who are engaged in technical work. 

 Repeated tests of both volumes show that practically 

 nothing has been omitted, and the long lists of con- 

 tributors and revisers for the two volumes, embracing 

 -men eminent in the railway world in Europe and 

 ^America, are a sufficient guarantee of the accuracy of 

 the work. The great difficulty which often arises of 

 finding a definition in one language which should have 

 its exact equivalent in another has been very satis- 

 factorily overcome, and the sketches render misunder- 

 standings almost impossible. ., 



In the volume dealing with railway construction 

 and operation, only those terms are included which 

 are of general importance in such work ; such details 

 as earthworks, bridge-construction, &c., could only 

 be exhaustively treated in volumes specially re- 

 served for them. Nevertheless, the railway expert will 

 •find that such subjects have been quite adequately 

 treated so far as he is concerned in this volume. In 

 preparing this volume, the subject has been divided 

 into sections to facilitate reference ; these sections in- 

 clude track, permanent-way, connections between 

 tracks, stations, signalling, and safety appliances, 

 railway service, &c., and one special section has been 

 given to electric railway installations. Each section 

 is again divided into a large number of subsections, 

 and, as these are given fully in the table of contents, 

 •it will bfe realised how much care has been taken to 

 facilitate reference. It is essential to those who are 

 engaged in the work of translating or making ex- 

 tracts from foreign technical books and journals that 

 any technical dictionary should be so arranged that 

 no time should be lost in ascertaining the ordinary 

 English equivalents to any unknown foreign words 

 or expressions ; the alphabetical index at the end of 

 each volume ensures this, and the division of the 

 whole subject into sections and subsections still fur- 

 ther makes for simplicity and saving of time. 



The sixth volume is given up entirely to the impor- 

 .tant subject of railway rolling stock. Here, again, 

 the. subject is divided up into a series of sections, 

 such as common equipment for locomotives and car- 

 riages, including such details as wheels, axles, draw- 

 .bar and buffer gear, brakes, &c. ; locomotives and 

 motor coaches ; carriages ; systems of lighting trains ; 

 rolling stock for electric railways; and, lastly, rail- 

 way workshops. This latter section is not, of course, 

 intended to cover the subject of machine tools gener- 

 ally, but only in so far as special methods and work- 

 ing are employed in railway workshops. 



With the help of these two volumes, the railway 

 engineer, and all those who are concerned with the 

 various industries which are devoted to the manu- 

 facture of the machinery and plant required 

 for the working and upkeep of the railways of the 

 world, will find that the task of keeping abreast of 

 what is being done in other countries will be greatly 

 facilitated. It is essential that every manufacturing 

 firm should endeavour to learn from the technical 

 NO. 2143, VOL. 85] 



Press what is being done in other lands, and a 

 thoroughly trustworthy technical dictionary, such as 

 this series now in course of publication, is indispens- 

 able for this purpose. These volumes should be found 

 in the head office of every firm which aspires to keep 

 itself up to date in business methods. T. H. B. 



PHYSICAL CHEMISTRY IN ITS GEOLOGICAL 

 APPLICATIONS. 



Principles of Chemical Geology : a Review of the 

 Application of the Equilibrium Theory to Geological 

 Problems. By Dr. J. V. Elsden. Pp. viii + 222. 

 (London : Whittaker and Co., 1910.) Price 55. net. 



ALTHOUGH it is generally recognised that the 

 new physical chemistry has far-reaching appli- 

 cations in geology, no less than in other branches of 

 science, little has yet been done to bring this home 

 directly, either to the working geologist or to the 

 student. In Van 't HofT's lectures on "Physical 

 Chemistry in the Service of the Sciences," the only 

 geological application discussed is that relating to the 

 crystallisation of salts from sea water. The results 

 of the chemist's beautiful investigation of this one 

 problem are the first-fruits of work on these lines, 

 and thev serve to show how wide a field still remains 

 to be harvested. Vogt and others have essayed to 

 apply the laws of solutions to igneous rock-magmas, 

 but in this much more difficult problem no more than 

 a beginning can yet be recorded. Meanwhile, we 

 suffer from that want of touch between workers in 

 different branches of science which is one of the less 

 happy consequences of specialisation. The chemist 

 has, in most cases, little acquaintance with geological 

 questions, while the geologist, of the older generation 

 at least, has not usually a working knowledge of 

 physical chemistry, or at best is unfamiliar with the 

 specific results, which have been obtained. 



This gap Dr. Elsden has now endeavoured to fill. 

 The book before us is a compendium of physico- 

 chemical principles as applied to the more important 

 questions of chemical geology and petrology. In 

 accordance with this plan, the arrangement adopted 

 is primarily a chemical one, thus differing from the 

 older method of Bischof and others. Successive chap- 

 ters deal with the crystalline and amorphous states, 

 viscosity, diffusion, solution, surface-tension, vapour- 

 pressure, polvmorphism, and mix-crystals. Through- 

 out the author insists that the key to the many 

 problems here touched "lies in the determination of 

 the conditions of equilibrium," and indeed this last 

 word occurs in the heading of almost every chapter. 

 Unfortunately, as is duly recognised, many geological 

 phenomena (such, e.g. as the glass in volcanic rocks) 

 prove that the adjustment of equilibrium maj'' be 

 indefinitely delayed. 



A surprising amount of matter is brought together 

 in the compass of these two hundred pages, and the 

 numerous references given in footnotes will be very 

 useful to the student. Sometimes, perhaps, this ful- 

 ness is gained rather at the expense of clearness of 

 treatment ; or it may be merely a wholesome caution 

 which makes the author content to cite conflicting 

 opinions and leave the question at issue open. Iq 



