November 3, i 



NA TURE 



proper relation to the accuracy attainable, even with per 

 feet manipulation, in any given process. It is the com 

 monest thing to find a pretension to accuracy of i part j 

 in 1000 where i in 50 would hardly be justified. 



Mr. Xewth does not introduce the ionic theory into his 

 explanations of analytical reactions. It is not difficult to 

 understand reluctance to embrace a theory which is still 

 young and still the object of adverse criticism. At the 

 same time it seems a great pity that a writer on analysis 

 should leave the student in ignorance of what, according 

 to a large number of eminent chemists, is the real key to 

 the chemistry of analysis. The ionic theory need not 

 have been woven into the fabric of the book ; but it, at 

 least, deserved a chapter and a fair hearing. 



Whilst a few defects are to be noticed in the book, it 

 is right to add that the merits are much more conspicuous ; 

 and it may be said, on the whole, that Mr. Newth's account 

 of analysis is wide in scope, exact in detail, and particu- 

 larly luminous in exposition. If it is used conscientiously 

 by duly prepared students, it will teach them a great deal 

 of chemistry. 



Prof.Wells's book is written on somewhat difl^erent lines, 

 Vet is characterised, like Mr. Newth's, by the attention 

 paid to the explanation rather than the mere description 

 of reactions. Prof. Wells, who has charge of the teaching 

 bf analytical chemistry and metallurgy in the Sheffield 

 'Scientific School of the Yale University, is evidently 

 'deeply impressed with the feeling that students tend to 

 ido their analytical work in a mechanical way, taking 

 'merely marching orders from their text-books. Instead, 

 therefore, of telling the student anything about the 

 Inetallic chlorides, the author contrives that the facts shall 

 be discovered by such instructions as : 



" Find by experiment which of the twenty-seven 

 (Solutions give precipitates when a few drops of hydro- 

 chloric acid, HCl, are added to i or 2 cc. in a test-tube. 

 Write the equations of the reactions and remember the 

 facts observed in this experiment as well as in those that 

 follow. Why are no precipitates produced in the solutions 

 tontaining chlorides ?" 



I The directions continue in the same strain. It must be 

 .observed that the student does not proceed on a natural 

 Voyage of discovery. At every port he opens another 

 (Sealed order, and takes the directed course wherever 

 t may lead. The value of this method of teaching 

 nalysis is open to serious doubt. The student is asked to 

 jperform twenty-seven experiments, of which all but three 

 are, practically speaking, blanks. The present writer's 

 experience is that operations of this kind pall intolerably 

 jupon a self-respecting student. We surely have here a 

 tase where a wrong sacrifice is made to pedagogic theory. 

 •In the early stages of education it is no doubt hardly 

 {possible to pay too much attention to method. Whilst 

 (habits of mind are being formed, and pupils are young 

 and docile, much may be permitted in the name of 

 imethod ; but a period arrives when the leading strings 

 jmust be rela.xed. As soon as a system of teaching is felt 

 by the pupil to be a system, it is apt to lose its value, and 

 to engender the resentment which every one feels on dis- 

 covering that he is being manoeuvred. The present 

 Avriter has had experience of the unintelligent student of 

 jpractical chemistry, and has tried Prof. Wells's device, 

 j NO. I 5 14, VOL. 59] 



among others. The result has not been at all encourag- 

 ing. The fact is, that by the time a student is fit to begin 

 the study of analytical chemistry he should be fit to avail 

 himself of straightforward explanations. If he is not fit, 

 strategy will do but little to mend matters. Prof Wells, 

 however, thinks differently after fourteen years' teaching 

 and it may be that things are different in America. 



Whilst offering this general criticism of Prof Wells's 

 system, it is right to add that the book is wholly good in 

 its scientific tendency, and that it contains abundant 

 evidence of the writer's experience and grasp of analytical 

 chemistry. The injunction that the student is to con- 

 struct his own tables of separations is much to be com- 

 mended. The second part of the book deals with theory ; 

 it embraces the ionic theory, and explains the phenomena 

 of analysis from that point of view. The explanations 

 are, it is to be feared, too brief and sketchy to be of much 

 use. They have a somewhat high-sounding logical form, 

 but do not always convey much substance. 



"There is a direct connection between the formation 

 of precipitates and insolubility. A compound which is 

 readily soluble in the liquid that is present cannot form a 

 precipitate in the presence of a sufficient amount of that 

 liquid." 



This surely was unnecessary. 



The chapter on equations is clear and useful. The 

 third part of the book gives an account of the properties 

 of the inorganic radicals in alphabetical order, and does 

 not purport to be more than a condensation of Fresenius. 

 It contains a summarised statement of what the student 

 is meant to have learned for himself by working through 

 Part i. 



Two " appendixes " to the book, consisting of eighteen 

 pages of labels, seem very unnecessary.; 



The third book before us is also of American origin. 

 It is intended for engineering students, though there is 

 no evidence of this special destination in the text. In 

 so far as the reactions are explained with fair complete- 

 ness, it is in advance of the customary analysis book. 

 The distinctive feature is to be found in a number of 

 large tables plotting an outline of reactions which occur 

 in the separation of the members of a group. By refer- 

 ence to the tables it is possible to see what is the maxi- 

 mum number of substances in any particular precipitate 

 or filtrate. Thus precipitate 35 may contain BaC03, SrC03, 

 CaCOj, whilst filtrate 35 maycontain MgCL NH^Cl, NaCl, 

 KCl, BaCl^ and CaCl., in traces, NH4OH, (NHJXOs. 

 The author states that these tables have been found of 

 much benefit to the student. 



In the beginning of the book we find the statement 

 that " in inorganic chemistry the bases comprise the 

 metals, and the acids the non-metallic elements (with a 

 few exceptions) " ; a little later — " all acids contain 

 hydrogen, which hydrogen is replaceable by a base " ; 

 and lastly — "bases have properties just the reverse of 

 acids. Among the inorganic compounds they usually 

 consist of hydroxyl in combination with a metal. Their 

 chief characteristic is their power of uniting with acids 

 to form neutral compounds." Could any better justifica- 

 tion be found for the remark, made early in this article 

 in reference to the dire effects of lingering dualistic 

 terminology? ARTHUR Smithells. 



