November i6, 1899] 



NA rURE 



53 



cited. " Heat a few pieces of zinc with a strong solution 

 of sodium hydroxide. What gas escapes ? What is 

 there in the solution ? From your previous experience, 

 what acids will dissolve zinc?" Or again, "To i c.c. of 

 silver nitrate solution add a little ammonium chloride 

 solution, and then a solution of some of the salt made 

 above [sodium thiosulphate]. Describe the phenomena, 

 and explain, using equations." 



It is obvious that each of these experiments opens up 

 a large subject, and will necessitate reference to a de- 

 scriptive text-book, and probably to a demonstrator as 

 well. This is, of course, eminently desirable, and there 

 can be little doubt that Dr. Hillyer's book, if properly 

 used, will prove a helpful laboratory manual. It ranges 

 over inorganic chemistry, and the selection of experi- 

 ments has been carefully directed to bring out the most 

 important facts and principles. . 



LItidusirie des Maiihes Coloranies Azoiques. Par 

 George F. Jaubert. Pp. 167, (Paris : Gauthier-Villars.) 

 It is over forty years since the late Dr. Peter Griess 

 placed at the disposal of chemists a reaction which has 

 since proved of such importance, both scieritifically and 

 technically, that a large literature is now in existence 

 dealing with the class of compounds known as azo- and 

 diazo-compounds. From the industrial side, -the most 

 important development has been the manufacture of a 

 group of colouring-matters which are now turned out on 

 a colossal scale, and which are so numerous in individual 

 members, that in the last edition of the " Tabellarische 

 Cbersicht " of Schultz and Julius (1897) no less than two 

 hundred and seventy-three distinct technical products of 

 this class were catalogued. The present little work is 

 one of the useful " Aide-Memoire " series from the 

 *' Encyclopedie Scientifique," published under the direc- 

 tion of M. Leaute of the Institute. It is fairly brought 

 down to date, and contains in a handy and portable form 

 a tabular list of the colouring-matters in question, in- 

 cluding also the nitro- and azoxy-compounds which find 

 place in technology. The little volume will be found 

 valuable by all engaged in this department of chemical 

 industry. R- M. 



Elemetitary Practical Mathematics. By Frank Castle, 

 M.I.M.E. Pp. x -V 401. (London : Macmillan and 

 Co., Ltd., 1899.) 

 In this book the student is carried rapidly through a 

 course of arithmetic, algebra, geometry and trigonometry 

 to some of the simpler problems of mensuration and 

 dynamics. The idea is to bring the desk and paper 

 work of the pupil into closer touch than heretofore with 

 the work of the shop or factory— in other words, to 

 indicate from the very beginning the practical value of 

 mathematical methods. 



The purely academic theorem or problem is to be 

 "taboo," or, in the words of the preface, "abstract 

 reasoning is to be relegated to the background, and 

 concrete facts are to form the basis of the student's 

 work." The principle is probably a sound one, but it 

 may be carried too far ; and experience alone will decide 

 as to the efficiency of the system embodied in Mr. 

 Castle's book. The student, if not otherwise instructed, 

 will find certain parts very hard to follow. Thus on 

 p. 341, in the discussion on maxima and minima, a 

 differential coefficient is suddenly introduced without a 

 word of explanation or apology. The great brevity, 

 which the limits of the book impose on many of the 

 sections, will also be a serious barrier to their ready in- 

 telligibility. As a general rule, the explanations and de- 

 scriptions are clear and accurate ; but we have noticed two 

 statements which, if not absolutely mcorrect, are, at any 

 rate, misleading. On p. 23 we read that "the invariable 

 interval of time between two consecutive southings of a 

 star is divided into 24 equal parts, each called an hour." 



NO. 1568, VOL. 61] 



True, but this is not the hour as usually understood and 

 practically used ; yet there is nothing in the context to 

 indicate the distinction between the sidereal and mean 

 solar hour. The other doubtful statement is on p. 290, 

 where we read : " Any change in the direction or speed 

 of a moving body is produced by force. When a force 

 acts in either of these ways it is said to do work." The 

 "direction of a moving body" is a curious truncated 

 phrase ; but the implication that a force always does 

 work when it alters the direction of motion of a moving 

 body is still more curious. Here truly are sinks of waste 

 of solar energy that were never dreamed of in the philo- 

 sophy of Helmholtz and Kelvin 1 These blemishes apart, 

 however, there is much to commend in the book. Con- 

 tracted arithmetical operations are strongly insisted upon. 

 The chapters on logarithms, the slide-rule, orthographic 

 projection and graphical methods, are particularly de- 

 serving of praise. The book is beautifully printed, the 

 illustrations are clear and well conceived, and the examples 

 — both in the text and in the exercises— are all of a 

 distinctly practical character. 

 The New Education. Manual Training : Woodwork. Hy 



Richard Wake. Pp. viii 4- 360. ( London : Chapman 



and Hall, Ltd., 1899.) 

 Manual training, or instruction in the use of tools, may 

 be made of great educational value if care is taken to 

 develop the rational and constructive faculties rather 

 than to produce dexterity in tool manipulation. The 

 author of this volume deals with the subject upon the 

 right lines, and the course described by him will en- 

 courage pupils to measure accurately, observe minutely, 

 and work with close attention to details— all of which are 

 desirable attributes to cultivate. A special feature of the 

 course is the effort made to develop the creative faculty 

 in children by inducing them to design for themselves the 

 simple models to be constructed in wood. No attempt is 

 made to describe woodwork of the ornamental character 

 which is often seen in school workshops ; each exercise 

 has a purpose, and that purpose is to educate. 



The book covers the requirements in manual training 

 for Standards V., VI. and VII. of public elementary 

 schools. It is well illustrated with working drawings and 

 reproductions from photographs showing pupils perform- 

 ing the various operations of woodwork. Teachers of 

 the subject will find the volume helpful and suggestive. 



The Naval Pioneers of Australia. By Louis Becke and 

 Walter Jeffery. VVith illustrations. Pp. xii 4- 314- 

 (London : John Murray, 1899.) 

 This is a pleasant and accurate compilation for popular 

 reading, based largely on the authoritative documents 

 now being published by the Government of New South 

 Wales. It is, in fact, a short history of the connection of 

 the British navy with Australia. The standpoint is that 

 of political rather than natural history ; but many 

 references are made to the large interest taken by Sir 

 Joseph Banks in the beginnings of Australian colonis- 

 ation. The problems of the first discovery of Australia 

 are scarcely touched on, and the book is in no sense 

 concerned with controversial questions. 



Arithmetical Exercises in Chemistry. By Leonard 

 Dobbin, Ph.D. Third Edition. Pp. vi 4- 52. (Edin- 

 burgh : James Thin, 1899.) 

 Prof. Crum Brown, who contributes a preface to this 

 book, points out that it contains clear descriptions of 

 "the principles involved in the calculations required in 

 dealing with chemical changes, and such physical changes 

 as are of special importance to junior students of chem- 

 istry." The exercises should be of value in fixing ideas 

 in the minds of students and illustrating the operations 

 of arithmetical chemistry. The ability to make such 

 simple calculations as are here given is essential to a 

 clear understanding of the laws of chemistry. 



