244 



NA TURE 



[January i i, 1906 



mean complete chemical changes, whilst often enough 

 they only express part of the chemical change that is 

 going on. Statistical data, the most useful inform- 

 ation to a merchant, are very imperfectly given. 

 Whilst, e.g., the statistics of ammonium sulphate 

 refer to the years 1902 and 1903, other more important 

 branches of chemical technology hark back as far as 

 the 'eighties of last century. 



If the question be asked whether this book would 

 prove useful to a chemist, a much more favourable 

 •opinion can be pronounced. The work will be found 

 very helpful, as a kind of " Repetitorium," to a 

 chemist who is reading up for examination. Re- 

 garded in this light, the book may be said to have been 

 written concisely and to contain an enormous amount 

 ;if information, put together in a clear and transparent 

 form. Naturally, the attempt of one single author 

 •to press the wide range of chemical technology into 

 • one small volume carries with it the germ of defect. 

 For in the present state of chemical technology it is 

 clearly impossible for any single person to write on 

 ever) hianch with the necessary authority or even 

 necessary knowledge. The inevitable consequence of 

 such an ambitious endeavour is that books of this 

 kind bear too patently the stamp of writing-desk 

 work. Only in the case of the electrolytical processes 

 dealing with alkali chlorides the author has called in 

 the assistance of an expert. He would have done 

 well to have extended this invitation to other 

 specialists. We therefore find throughout the book 

 many statements which could have been put right by 

 an expert, and we also notice some important 

 omissions. Moreover, some of the weakest chapters, 

 such as those on " leather industry " and " fats and 

 nils," would have been brought into line with the 

 iforementioned chapter on electrolysis. The least 

 satisfactory part of the book are the illustrations. 

 Some of lh. 111 have done service for half a century, 

 and might have been given their well-earned rest. 

 Others are more in the nature of pictures which 

 convej no information. Others, again, such as the 

 illustration of a native indigo plant, can only provoke 

 1 smile. 1 1 



OUR BOOK SHELF. 

 Future Forest Trees. By A. H. Unwin Pp. 108. 



(London : T. Fisher Unwin, 1905.) Price 7s. 6d. 



net. 

 Within recent years our forestry literature has been 

 rapidly and steadily on the increase, which may be 

 taken as a sign that more attention is now being 

 given to matters sylvicultural than formerly. The 

 above work is one of the most recent additions, and 

 its thoroughly sound, practical, and scientific character 

 should secure it a wide circulation, not only in this 

 country, but also in America, to which it equally 

 refers. 



rin' title chosen by the author, " Future Forest 

 Trees," refers to those exotic, deciduous, and coni- 

 ferous species of East, West, and North American 

 trees which might with advantage be introduced into 

 our forests. The work embodies the author's own 

 personal experience, as well as the results gained by 

 more than 100 years of extended experiments which 

 have been carried out in Germany. 



NO. 1889, VOL 73l 



i he selection of exotic species as future forest trees 

 is not by any means so easy a task as one might at 

 first sight suppose. To justify its introduction and 

 cultivation the new species must have some distinct 

 advantageous characteristics which are not possessed 

 by our indigenous trees, such as greater rapidity in 

 growth, greater resistance to adverse climatic condi- 

 tions (tor example, wind, heat, cold, rain, and snow), 

 greater adaptability to the poorer classes of soil, and 

 such like. 



It is to Prof. H. Mayr, of Munich, to whom this 

 book is dedicated, that we are indebted for so much 

 valuable information on this very important question, 

 especially as regards the geographical distribution of 

 forest trees. 



The first part of the book deals with the imports of 

 American timber to the German market. Importing 

 timber to Germany, the home of forestry, sounds a 

 little like carting coals to Newcastle; nevertheless, 

 tin re air at least two sufficient reasons, firstly, be- 

 cause some of these timbers are at present not culti- 

 vated in that country, and, secondly, it is a will- 

 known fact that the world's supply of timber is not 

 inexhaustible, and is, in fact, rapidly on the decrease. 

 Hence, while Germany can obtain timber at a reason- 

 able price from abroad, she is conserving her own 

 forest reserves with the full knowledge that at no 

 very remote date the price of timber will have risen 

 to a figure which will amply justify this policy of 

 conservation. Part ii. gives the general results of 

 planting experiments with American trees in 

 Germany. Austria, Gnat Britain, and Switzerland; 

 and part iii. deals with the sylvicultural characteristics 

 and treatment Of the various American species of 

 trees. 



We heartily commend this book to all those who 

 ire interested in or connected with forestry, as it 

 forms an excellent guide to the cultivation of species 

 which are likely in the course of time fully to justify 

 their introduction. 



Elements of Quantitative Analysis. By Dr. G. H. 



Bailev. Pp. x + 246. (London : Macmillan and 



Co., Ltd., 1905.) Price 4s. 6d. 

 After the consideration of some preliminary matters, 

 the author, within the compass of less than two 

 hundred small pages, treats of almost every branch 

 of quantitative chemical analysis, including minerals 

 of many sorts, water, fuel, the products of alkali 

 factories, manures, organic substances, soap, oils 

 and fats, and gases. It follows that the space devoted 

 to each section is very small, and in many cases it 

 would be more correct to say that the methods are 

 indicated rather than described. This economy of 

 words and space sometimes leads to instructions that 

 might cause accidents, as in the description of 

 Kjeldahl's method of estimating nitrogen, where the 

 student is instructed to boil the substance with fuming 

 sulphuric acid, &c, then to " allow to cool and add 

 a tolerable excess, about 50 grams will suffice, of 

 caustic soda. . . . Distill off the ammonia," &c. In 

 other cases the desire to be brief leaves the student 

 without instructions, as in the analysis of water, in 

 which he is told to determine the free and albumenoid 

 ammonia, and referred for the method to a simple 

 description of the estimation of ammonia by Nessler's 

 solution. On the other hand, it is a pleasure to notice 

 that some methods an 1 given that are not generally- 

 known, such as the colorimetric estimation of 

 titanium by means of hydrogen peroxide. 



The educational value of the work suggested (to 

 which the author refers in his preface) would have 

 been enhanced if the chemistry of the operations and 

 the specific aims of the advisable manipulative pre- 



