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NATURE 



[January 12, 191 1 



PRINCIPLES OF ANALYTICAL CHEMISTRY. 



Theoretical Principles of the Methods of Analytical 

 Chemistry based upon Chemical Reactions. By 

 Prof. M. G. Chesneau. Authorised translation by 

 Prof. Azariah Thomas Lincoln and Prof. David 

 Hobart Carnahan. Pp. x+184. (New York: The 

 Macmillan Co. ; London : Macmillan and Co., 

 Ltd., 19 10.) Price 7s. 6d. net. 



IN the introduction it is stated that this book re- 

 presents the reproduction of a series of lectures 

 delivered in the College de France on the principles 

 involved in the methods of analytical chemistry. The 

 reversible and irreversible reactions which are in- 

 volved in analytical processes are discussed, on the 

 one hand, from the point of view of the theory of 

 electrolytic association, and, on the other, from that 

 of the heat changes which accompany these reactions. 



It is obvious that the comparative examination of 

 the facts of analytical chemistry from these two 

 points of view represents a theme to which consider- 

 able interest would attach if the comparison were 

 made by a chemist thoroughly familiar with both 

 aspects of the question, and yet untrammelled by 

 adhesion to any particular doctrine. Unfortunately 

 this is not the case, and it is perhaps partly due to 

 the author's lack of familiarity with the present posi- 

 tion of the ionic theory that his verdict is given in 

 favour of the so-called calorimetric theory. The 

 evidence which leads to this result is very far from 

 convincing, for whereas great stress is laid on the 

 difficulties, real and apparent, which are involved in 

 the adoption of the ionic theory, the improbable con- 

 sequences which attach to the application of the 

 calorimetric hypothesis are accepted without criticism 



Only a brief reference can be made to a few of the 

 many points which call for comment. In terms of 

 the calorimetric theory we find that acids are classified 

 as strong, medium, and weak according to the quan- 

 tities of heat liberated in the process of neutralisation. 

 The decrease in the activity of a weak base, such as 

 ammonia, on the addition of a corresponding salt, is 

 attributed to the production of acid by hydrolytic de- 

 composition of the salt. An attempt is made to 

 refute the ionic explanation of the similar influence 

 of salts on weak acids by reference to experiments on 

 the rate of solution of zinc in solutions of acetic acid 

 to which various metallic acetates were added. Such 

 experiments are in reality of far too complicated a 

 nature to allow of the results being interpreted in 

 favour of or against any particular theory. 



In the discussion of osmotic pressure, the early 

 measurements of Pfeffer and Ponsot are cited, but no 

 reference whatever is made to the work of Morse 

 and his collaborators, or to that of Hartley and the 

 Earl of Berkeley. 



Certain generalisations, drawn by Ponsot from 

 transport measurements by Chassy, are brought for- 

 ward as being more important than all the excellent 

 experimental work done on the subject from the time 

 of Hittorf onwards. Here, as in so many other in- 

 stances, the lack of the author's knowledge of recent 

 work on the nature of solutions of salts is lamentably 

 apparent. 



NO. 2150, VOL. 85] 



In the treatment of indicators, Ostwald's long- 

 discarded ionic explanation is the only one which the 

 author sees fit to compare with that based upon the 

 calorimetric theor)'. 



These references suffice to indicate that the author 

 has failed to do justice to his subject, but this review 

 would be incomplete if attention were not directed 

 to the unsatisfactory character of the translation. In 

 view of the fact that the academic title of the second 

 translator is that of associate professor of Romance 

 languages, a rendering of the original into tolerable 

 English might have been reasonably expected. To 

 show that this anticipation is not fulfilled, the first 

 paragraph on p. 4 may be quoted : — 



"The processes of analytical chemistry consist, in 

 general, in bringing each element successively to the 

 state of a definite compound in a final system, formed 

 of distinct phases, whose nature lends itself easily to 

 a separation by purely mechanical processes." 



This conglomeration would appear to be the result 

 of a too literal translation. 



Apart from the publisher's share in the production 

 of the work, the reviewer can find nothing to recom- 

 mend it, and the translation represents a good deal of 

 misspent time and energy. H. M. Dawson. 



MORE MOSQUITOES. 

 A Monograph of the Culicidae or Mosquitoes. Mainly 

 Compiled from Collections Received at the British 

 Museum. By Fred V. Theobald. Vol. v. Pp. xv + 

 646 + 6 plates. (London : British Museum (Natural 

 History), Longmans and Co., B. Quaritch, and 

 Dulau and Co., 1910.) Price il. 55. 



SOME few years ago a critic observed that, owing 

 to the system of classification adopted for the 

 Culicidae, to describe a new species " and call it a 

 genus " was far easier than to determine its true 

 systematic position. Since then, such has been the 

 activity of genus-makers, the condition of affairs as 

 regards the nomenclature and taxonomy of the known 

 mosquitoes has become infinitely worse. No ento- 

 mologist of repute will deny that, were characters so 

 trivial as those now employed for the distinction of 

 most of the so-called "genera" amonp^ Culicidae made 

 use of in other orders of insects, or in other families 

 of Diptera, the result would be little short of chaos. 

 Sooner or later the whole question of mosquito classi- 

 fication will have to be reconsidered ; meanwhile the 

 subject awaits the advent of a properly qualified 

 systematist, gifted with breadth of view and possess- 

 ing a sound knowledge of fundamental principles. 



The book before us, which is a continuation, and, 

 in some respects, a rdsumd of the previously published 

 volumes of Mr. Theobald's well-known work, is con- 

 structed upon the same lines as its predecessors, and 

 certainly bears witness to the industry of its author. 

 We are told in the " Introduction " that, since the 

 appearance of vol. iv. in 1907, the genera of Culicidae 

 have been increased by twenty-one and the recognised 

 species by no fewer than three hundred and ninety- 

 two, though it would seem that not all of the latter 

 are actually new; thirteen of the genera, however, 

 and eighty of the species are now described for the 



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