November 28, 1907] 



NATURE 



75 



begun at school and carried to the end of part i. 

 slowly and methodically, it would form an excellent 

 groundwork for a subsi^quent college course. 



There is little to criticise. Attention should be 

 directed to one omission which is not uncommon in 

 elementary text-books. It states on p. 40 that " you 

 have found out that hydrogen is contained in acids." 

 It is quite true that hydrogen is described as being 

 obtained by the action of acids on metals, but there 

 is no suggestion as to where the gas comes from, and, 

 so far as any information to the contrary goes, it 

 might just as well come from the metal. Some 

 explanation or comment is called for, because a few 

 pages further on the action of acids on carbonates is 

 described, and in this case the process appears to be 

 reversed, the gas coming from the solid and not from 

 the acid. 



. W'r should like to see electrolysis entirely banished 

 from elementary books. The decomposition of water 

 by tile current is a mysterious and unconvincing ex- 

 periment. It is difficult to understand why the gases 

 appear at the ends of two different platinum wires, 

 and why the volumes which collect should represent 

 the true composition of the liquid. The union of the 

 two gases to form water by means of the electric 

 sparl< only serves to heighten the mystery. A careful 

 drilling in these two operations gives the schoolboy 

 an agent which in his imagination w'ill produce or 

 decompose every compound gas that ever existed, and 

 he uses this knowledge, as we all know, with a reck- 

 less facility. It is a satisfaction to find that Lavoisier 

 did not, as we are generally told, institute experiments 

 to prove the conservation of matter, but, as the author 

 states, did several experiments which showed it. 

 Lavoisier simply took the principle for granted, as 

 most chemists had done before him, from Boyle 

 onward. Dalton, by the war, was not exactly a 

 schoolmaster in Manchester, though he served in that 

 capacify at Kendal. 



The attractive appearance, substantial get-up, and 

 exquisitely drawn diagrams of Dr. Martin's book 

 command at once a careful perusal. It differs essen- 

 tially from the foregoing in confining itself to the 

 practical, or, perhaps more strictly, to the manipula- 

 tive side of chemistry. Each experiment stands alone, 

 and has no necessary connection with the one that pre- 

 cedes or follows it, minute directions being given for 

 its performance. It is also for Army and matricula- 

 tion candidates, and will no doubt prove very useful 

 to both candidate and teacher as a laboratory vadc 

 inncum. 



Mr. G. M. Norman's " Systematic Practical Organic 

 Chemistry " is one of the organised science series, and 

 is intended to meet the requirements of stages i. and ii. 

 of the Board of Education examination. It contains a 

 description of a series of simple preparations and a 

 varic ty of useful tests. It is satisfactory to find that 

 the Board of Education now requires evidence that 

 the candidate has carried out a number of preparations 

 before presenting himself. It is to be hoped that 

 before long the Board of Education will take the 

 further step of requiring the evidence without the 

 candidate. No kind of chemistry lends itself to a 

 two or three hours' practical examination, organic 

 NO. 1987, VOL. 77J 



chemistry perhaps least of all, and the evidence of 

 knowledge elicited by the sort of experiment set at 

 these examinations has very little value. That, how- 

 ever, does not impair the usefulness of the book under 

 review, which may be safely commended both for the 

 purpose it is intended to fulfil and also as an intro- 

 duction to practical organic chemistry. 



Messrs. Price and Twiss's " Practical Organic 

 Chemistry," like the preceding volume, owes its 

 origin to the new syllabus of the Board of Education, 

 and is intended to meet to some extent the require- 

 ments of stage iii. (theoretical organic), as well as 

 to prepare for stages i. and ii. (practical organic) 

 of the Board's examinati.on. The treatment of the 

 subject is full and comprehensive. It contains the 

 usual series of simple preparations, an account of the 

 qualitative and quantitative examination of organic 

 compounds, molecular-weight estimations, and useful 

 schemes of analysis. Without introducing any 

 specially novel features, it presents a fairly complete 

 programme of practical study which if carefully 

 carried out should form a sound basis for subsequent 

 research in organic chemistry. The descriptions are 

 clear and concise, and the illustrations, though not 

 numerous, are probably sufficient for the purpose. It 

 may be recommended as a thoroughly safe book for 

 the laboratory. 



Mr. Weston's book on the detection of organic 

 compounds deals, as it states, with qualitative methods 

 only. That such a book should have reached a second 

 edition and should serve the needs of the final B.Sc. 

 of the London University and of the honours stage of 

 the Board of Education is a hopeful sign of the times, 

 if we must have this kind of test. Such defects as the 

 book possesses, and they are not numerous, are to be 

 attributed to the fact that it is written to meet the 

 requirements of a practical examination where time 

 is an important factor. 



The author confines his attention to the study of 

 pure organic substances only, giving directions which, 

 if carefully followed, should lead to their detection, and 

 at the same time to the acquisition of much useful 

 information and manipulative skill on the part of the 

 student. 



This is all thoroughly sound and satisfactory so 

 long as it is recognised that it is an introduction to 

 analysis, and that the real laboratory problems involve 

 such things as the separation of mixtures and the 

 purification of impure products. It appears from a 

 general perusal of the book that some of the direc- 

 tions need amplifying. This refers more particularly 

 to the means of ascertaining the presence of oxygen, 

 upon which the grouping of the compounds is based, 

 to the identification of aromatic hydrocarbons (p. 12), 

 to Fenton's oxidation method for detecting keto- 

 hexoses (p. 47), and to Fischer's benzaldehyde green 

 reaction for aldehydes (p. 40). We^ would also sug- 

 gest the following additions or modifications in a 

 future edition : — the use of bromo- and nitro-phenyl- 

 hydrazine, methyl sulphate and semicarbazide as use- 

 ful reagents and of Tollens' reagent (the name, by the 

 way, is spelt with an " s ") for pentoses, also the 

 consistent use of the modern system of nomenclature 

 and a good index. J. B. C. 



