April 6, 191 1] 



NATURE 



171 



In chapter i. the nitrous and nitric esters are dealt 

 with, while chapters ii. and iii. contain an excellent 

 account of the amines. 



Throughout the book the application of physical 

 methods to the study of the problems of organic 

 chemistry is continually brought to the notice of the 

 reader, and the importance of the study of the 

 mechanism of reactions and the quantitative side of 

 the subject is emphasised : the latter is introduced by 

 an excellent discussion on the strength of the amines 

 as bases. 



The constitution and reactions of the triphenyl- 

 methane dyes are treated very fully, but the account 

 of the stereoisomerism of quinquevalent nitrogen com- 

 pounds is not entirely satisfactory. 



Chapter iv. contains an account of the amides, in- 

 cluding a good discussion of the mechanism of the 

 Hofmann reaction. 



Derivations of hydroxylamine are dealt with in 

 chapter v., in which the transformations of phenyl 

 hydroxylamine are described very fully, and an ad- 

 mirable account of the isomerism of oximes is pre- 

 sented. The evidence for Hantzsch and Werner's 

 hypothesis of stereoisomerism, culminating in the 

 strongest argument yet adduced in its favour, namely, 

 the resolution of oximino-cyclohexane carboxylic acid 

 and into optically active components by Mills and 

 Bain, is clearly expounded, but the statement that 

 this theory is universally accepted is scarcely justified 

 even now. A lucid account of the Beckmann trans- 

 formation and its mechanism is also included in this 

 chapter. 



Chapters vi. and vii, deal with the nitroso- and 

 nitro-compounds, and include a discussion of the con- 

 Ntitution of the nitrophenols and their salts, the bearing 

 •f this on the problem of the relation of colour to 

 r!)nstitution in these and similar substances, and also 

 a very good account of the reduction of nitro-com- 

 pounds and of the oxidation of amines. 



The cyanogen compounds are described in chapter 

 ix., in which the problem of the constitutions of hydro- 

 cyanic and fulminic acids and their salts occupies a 

 prominent place. The evidence brought forward by 

 Nef and other workers in support of the view that 

 fulminic acid is the oxime of carbon monoxide seems 

 now incontrovertible. None of the hypotheses sug- 

 gested to account for the properties and reactions of 

 hydrocyanic acid and the cyanides can be regarded as 

 entirely satisfactory, but few will agree with the state- 

 ment that " prussic acid is tautomeric, and is prob- 

 ably a mixture of two forms," since the same line of 

 reasoning, as shown by Wade, would necessitate a 

 similar assumption in the case of silver cyanide. 



In division iii., chapter xi., which deals with the 

 diazo-compounds, is the most interesting; here, how- 

 ever, we feel that the subject is not presented to the 

 student in a way which makes him understand clearly 

 the difficulties of the problem under discussion. Cer- 

 tain statements are put forward as if they were de- 

 finitely established facts ; whereas, on account of the 

 experimental difficulties with which the problem is 

 ' iset, the evidence on which some of these statements 



re based is not conclusive enough to justify one in 

 iccepting them without question. In the case of the 

 NO. 2162, VOL. 86] 



diazo-compounds, the hypothesis of stereoisomerism 

 does not rest on such a secure basis as in the case of 

 the oximes, and it is still possible that the facts may 

 be explicable on the basis of the structural laws with- 

 out assuming stereoisomerism. 



Uric acid and related compounds are treated briefly 

 in chapter xv. 



In division iv. the fatty diazo-compounds receive 

 due attention, the pyridine and quinoline group are 

 treated briefly, while coniine, piperine, and nicotine 

 are the only alkaloids discussed. 



A few errors, such as formaldehyde for formanilide 

 (p. 82), and minerals instead of mineral acids (p. 209), 

 were noticed, but we regret to find certain colloquial 

 expressions, such as "A readily goes over into B," 

 occurring so frequently ; and the statement that a 

 substance "can be broken, up into two optically active 

 forms," (p. 103), is hardly a correct or conventional 

 description of the process. 



The book contains excellent summaries of the present 

 state of our knowledge on a large number of sub- 

 jects, including many of the most controversial matters 

 that have recently occupied the attention of chemists. 



Usually the account of each subject will be found to 

 include the most recent work of importance, though 

 we notice the omission of the recent work on the 

 mechanism of the transformation of chloroamines into 

 chloroanilines. 



Unfortunately the author often gives the impression 

 that he treats a hypothesis or a theory as. a fact, an 

 attitude which v^e cannot regard as a desirable one 

 for the student to adopt. 



The student, for whom the book is intended, will 

 find it will well repay careful study, and will discover 

 in it much food for thought, while the author is to be 

 congratulated on the production of a very useful work. 



H. O. J. 



SCIENCE AND HISTORY. 

 The Cambridge Modern History. Planned by the late 

 Lord Acton. Vol. xii. : "The Latest Age." Pp. 

 xxxiv+1033. (Cambridge: University Press, igio.) 

 Price lbs. net. 



A COMPREHENSIVE and philosophical history of 

 science in "The Latest Age" would be one of 

 the most valuable and interesting works which it 

 would be possible to produce, but it was not the pur- 

 pose of the volume before us to produce it. Of its 

 thousand pages only fifty have any special interest for 

 students of science, the twenty-six pages of Mr. 

 Whetham's chapter on "The Scientific Age" and the 

 twenty-four pages of Mr. Rogers' " Modern Explora- 

 tions." In so narrow a space it is not to be expected 

 that there will be much that is novel or profound. 

 Mr. Rogers can do little more than record a long list 

 of names and dates ; he cannot describe the effect upon 

 modern civilisation of the discoveries without dupli- 

 cating the work of other authors, to whom the reader 

 is frequently referred. The present reviewer cannot 

 express any judgment as to the accuracy or complete- 

 ness of the list, but for these qualities the author's 

 reputation is a sufficient guarantee. Mr. Whetham 

 has rather more scope for comment, expressed with 



