2i8 



NATURE 



[April 22, 1920 



ments, as witness the references to rotary filters, 

 catalytic action, hydrogenation of fats, etc. 



The ordinary business man engaged in dealing 

 with the products of chemical industry will 

 undoubtedly derive considerable benefit from the 

 perusal of this volume. The style is clear enough 

 to be intelligible even to the non-technical 

 reader. 



" (3) Fuel and water are such important subjects 

 industrially that any book dealing with them is 

 bound . to receive serious attention from every 

 works chemist and steam user. The present work 

 (now in its second edition) meets a well-defined 

 want in that it gives trustworthy arid up-to-date 

 technical methods of analysing fuel, water, and 

 gas. ' 



Part i. deals with fuel, fuel sampling, analysis 

 of fuel, thermal values of fuel, etc., and is excel- 

 lent. Part ii. ■ deals with water as applied to 

 technical purposes; methods' of sampling and 

 analysing it, of softening, and of calculating the 

 amount of softening materials to lae added, are 

 given in full. Here, in acbncise form, are the 

 materials upon which a practical opinion can be 

 formed as to the best methods of dealing- with 

 any given type of water. The subject of part iii. 

 is waste gases, their sampling, analysis, and valua- 

 tion. • ■/ 



'The work is written by an authority who is in 

 practical touch 'With the numerous and difficult 

 problem^! relating to fuel and water which every 

 wo»ks>Ghemiist has to handle. It can be recom- 

 inended *to' every industrial chemist. 



(4). The author has achieved his aim of produc- 

 ing z. "popular" dictionary of chemistry, and the 

 work; so far as it goes, is Very complete, almost 

 every well-known chemical or piece of chemical 

 apparatus being briefly mentioried. It is very 

 difficult to see, however, for what class of reader 

 Such a work is intended. For purposes of strict 

 reference the volume is far too "popular." For 

 e>i:ample, on looking up the woi*d "pyridine," 

 we- are informed that it is' "a nitrogenous base 

 present in bone oil, and in tar obtained from 

 Shale arid coal." No m^htiori' iS riiade of its boil- 

 Frig-: poirit, specific gravity, constitutional formula, 

 solubilities, etc., which' the average reader would 

 i-fequire.' This is typical of the work. In the 

 reviewer's experience, no one looks up chemical 

 ferfns" - for ' amuserhent. Definite quantitative 

 ihformation ' is wh^t the usef of a dictionary 

 recJUires in hinety-riine cases ' oiit of a hundred, 

 arid it is these quantitative data 'which are so con- 

 !^ifcuo>usty lacking in the present volume. ■ The 

 Qt5?»staTifs of rriost^ of the materials should haVfi 

 b^eiv gfiveh in a "work of this kind. G. M. • 



NO. 2634, VOL. 105] 



Our Bookshelf. 



The Theory of Heat. By Prof. Thomas Preston. 



Third edition. Edited by J. Rogerson Cotter. 



Pp. xix + 840. (Macmillan and Co., Ltd., 1919.) 



Price 255. net. 

 It is pleasant to meet an old friend still going 

 strong in spite of years and changing fashions. 

 In these days of rapid progress a quarter of a 

 century is a long period in the life of a book 

 dealing with a living science. The secret of the 

 continued popularity of Preston's work is no 

 doubt to be found in the fact that the book was 

 written as a labour of love in the interests of true 

 scientific education, instead of being merely com- 

 piled to suit an arbitrary standard or syllabus, 

 adapted to a particular type of student, or a 

 special limit of mathematical attainment. The 

 object has been to give a comprehensive survey 

 of the development of the theory of heat from an 

 historical point of view, which possesses many, 

 advantages in the exposition of a scientific 

 subject. 



The historical order of evolution, iDoth in 

 theory and in experiment, generally fallows the 

 natural processes of reasoning of the human mind, 

 and introduces fresh ideas in a regular sequence 

 in which they are readily assimilated. The de- 

 ductive method, starting with a general law or 

 formula, may frequently provide a more direct 

 means of arriving at any particular result or 

 practical application, but it tends to obscure the 

 essential foundation on experiment, and to rob 

 the subject of human interest. From the point 

 of view of the general reader, as distinguished 

 frorh the special student, there can be no com- 

 parison between the two methods. There is an 

 illusion of finality in the deductive method which 

 appeals to the mathematical mind, but the his- 

 torical method, when illustrated, as in Preston, 

 by a critical discussion of typical experiments, is 

 the more sug-gestive, inspiring the student to 

 think for himself and to make further advances. 



The book is so well known that it only remains 

 to add that Mr, Cotter has shown 'himself to be 

 a most sympathetic arid capable editor in both 

 pruning and .grafting. The important additions, 

 on recent advances in the theory of radiation and 

 specific heat,, and on the kinetic theory of gases, 

 are admirable summaries, conceived and carried 

 out in the spirit of the original. H. L. C. 



Royal Botanic Gardens, Kew : Bulletin of Mis- 

 cellaneous Information, 1919. Pp. iv + 459-1-39. 

 (London: H.M.S.O., 1919.) Price 45. 6d. net. 

 This volume contains the ten numbers of the 

 Kew Bulletin which were published at in- 

 tervals from April to December, 1919. The thirty- 

 three articles include .papers and miscellaneovis 

 notes of both economic and . strictly. - botanical 

 interest. .Mr. J. H. Holland contributes a useful 

 list 'of food apd iodder plants arranged under their 

 res^ecftive'f lilies, with- notes on- their' origin, 

 tises;'-popi^f names, etc; - There are • alsb papers 



