86 



KNOWLEDGE. 



[ApBn, 1, 1898. 



work. Drs. Colman and Harden have taken part in the 

 sweeping changes which have been necessary to bring the 

 work into harmony with the present condition of chemical 

 science, the systematic description of the metallic elements 

 and their derivatives having been re-arranged in accord- 

 ance with Mendeleeff's — the Eussian chemist — natural 

 classification, which resolves the elements into eight 

 groups, the members of each group showing in most 

 cases a close connection with each other. By thus taking 

 advantage of the hint aiibrded by the natural gamut of 

 the elements, so to speak, the study of chemistry becomes, 

 in a way, comparable to the study of botany or zoology, 

 the eight groups of elements being the equivalents of the 

 chief representatives of the great groups of plants and 

 animals, while the individual members of each group may 

 be likened to the different species — all bearing certain 

 characters in common, but with specific differences. Such 

 a relation between the organic and inorganic is not incon- 

 sistent with the unity which science has shown to exist in 

 the universe, and the sooner this method of conveying a 

 knowledge of the chemical elements becomes general the 

 better it will be for all concerned. Chemistry, however, 

 has in recent years grown to such gigantic proportions 

 in both its main branches, organic and inorganic, 

 as well as in its theoretical and practical aspects, 

 that a book, in order to be of maximum value to 

 a student, must be consistent throughout. If it is a 

 book purporting to deal with the principles of the science 

 it must steer clear of the technical or industrial applica- 

 tions, otherwise there is sure to be a too apparent deficiency 

 somewhere. Special treatises are required, and exist, 

 nowadays, for such purposes as soap and alkali making, 

 the metallurgy of iron, copper, etc., and the extraction of 

 gold and silver from their ores. In the article on gold 

 mining, for example, in this work much space is occupied 

 on such subjects as the capital and labour required in the 

 working of auriferous deposits, which are certainly outside 

 the domain of theory, and yet not full enough to be of 

 practical value to the actual miner. The same remarks 

 would apply in the case of the section on iron smelting 

 and the Bessemer steel process, as well as several other 

 chapters, such as the manufacture of glass, bleaching 

 powder, and so on. A proper division of labour in matters 

 literary as well as industrial has its advantages. In the 

 case under consideration, had the authors confined them- 

 selves to the pure principles of chemistry, and reserved 

 the technical portions for books professedly practical, the 

 book need not have swollen to its present dimensions, and 

 might then, at a lower figure, have been accessible to 

 students in general ; whereas it is now almost entirely con- 

 fined to libraries, where it can only be casually consulted, 

 and its many excellencies are thus buried as far as the 

 great majority of chemical students are concerned. 



Nates on Carpentry and .Joiner ij. By Thomas Jay Evans. 

 Elementary Course. (Chapman ct Hall.) Illustrated. 

 7s. 6d. Students preparing for the technical examinations 

 of the City and GuOds of London Institute, the Technical 

 Education Board of the London County Council, and 

 other examining bodies, will find here a reliable guide. 

 The subjects included are practical geometry, graphic 

 arithmetic and statics, elementary carpentry and joinery, 

 and mensuration — a course of instruction well adapted for 

 apprentices who desire to acquire a thorough knowledge 

 of the principles underlying their craft. The text is lucid, 

 the diagrams large and well drawn, and, where necessary, 

 in the geometrical portion of the book, practical methods of 

 solving problems are given such as the workman would be 

 required to use in the shop. The section dealing with 

 graphic statics and mechanical contrivances is particularly 



good. Drawing, of course, takes the place of calculation 

 in this section, and Mr. Evans has, we think, succeeded in 

 presenting an intelligible exposition of the principles 

 involved in this useful method of computing strains and 

 stresses. Isometric projection, in both its theoretical and 

 practical aspects, comes in here for a fuller and more 

 luminous treatment than we have ever seen before in a 

 book of this kind ; and, considering its value in practice, we 

 are of opinion that the author has acted wisely in making 

 this departure, although it has been somewhat at the 

 expense of other important sections — the resolution of 

 forces for example, the treatment of which is rather meagre, 

 and yet the subject is one difficult to comprehend, espe- 

 cially by students whose groundwork in mathematics is 

 circumscribed — a condition of things which nearly always 

 obtains among the artizan classes. On the whole, how- 

 ever, we have nothing but praise for Mr. Evans's work. 

 He has so subordinated and dovetailed the subjects 

 forming the groundwork of an artizan's education that we 

 venture to think there is no better book available for such 

 a purpose. 



Glimpses into Plant Life. By Mrs. Brightwen, f.e.s. 

 (Fisher Unwin.) Illustrated. Mrs. Brightwen is well 

 known for her writings for young people, and this book is 

 executed in her usual clear and pleasant style. It is written 

 with the intention of preparing the " minds of young 

 people for the study of botany by explaining in the simplest 

 language some of the elementary phenomena of plant 

 life." For this purpose we are sure it will be successful. 

 Some of the many subjects dealt with are roots, tree 

 stems, leaves, flowers, fertilization, fruit, and habit of 

 growth in plants. The illustrations are good and adequate, 

 and a useful glossary of scientific terms is provided. We 

 have no hesitation in heartily recommending the book to 

 young botanists, or, indeed, would-be botanists of any age. 



The Eh'itients of Hypnotism. By Ralph Harry Vincent. 

 Second Edition. (Kegan Paul.) 5s. If the amount of 

 literature published on a subject is a measure of its worth, 

 then hypnotism is insinuating itself more and more into 

 popular favour in spite of the ignominy heaped upon it by 

 the practices of the professional entertainer, the charlatan, 

 the juggler, and the trickster, who have laid their hands 

 on the much-suffering science, for the number of books 

 on the subject is now not only large but also rapidly 

 increasing. The public, which in the main is entirely 

 ignorant of the nature of hypnotism, has always regarded 

 the subject as something akin to the supernatural, and 

 quacks have made their fortunes by availing themselves of 

 this weakness and mesmerising human beings in the 

 presence of large assembUes ; hence, mesmerism has long 

 been a sort of byword for all that is low and contemptible. 

 Hypnotism has also antiquity to recommend it — if age be 

 a virtue in matters intellectual — for it dates back as far as 

 the year 15.52 b.c, when it was practised in Egypt. The 

 early kings of France were credited with curing people by 

 the " royal touch "; and even in Queen Anne's time faith in 

 this mode of cure was still in vogue. Aa to the ultimate 

 value of hypnotic science it is difficult, at this stage, 

 to form any clear notion ; but Mr. Vincent has certainly 

 made the subject attractive, and, by numerous footnotes of 

 reference to literature of this kind, has invested his work 

 with a fund of information which will be specially accept- 

 able to those who wish to pursue their studies further than 

 is possible by the aid of a single volume. A chapter 

 on the use of hypnotism in detecting crime, and the 

 medical treatment of patients by mesmerism, concludes the 

 book — a chapter, by the way, which we think might with 

 advantage be amplified in a subsequent edition. Some 

 noteworthy remarks are advanced on the way in which 



