332 



NATURE 



[May 20, 1909 



has produced its useful effect. From this point of 

 view, organic chemistry, with its innumerable com- 

 pounds, offers precious opportunities, but inorganic 

 chemists also, though less favourably situated, are too 

 often led into this artificial adding to the number of 

 real substances. Taking a large general treatise on 

 chemistry, M. le Chatelier hazards the opinion that 

 at least half the substances described have never 

 had any existence. It is, therefore, of great import- 

 ance to give young chemists a timely respect for ex- 

 actitude, to accustom them, not only to make measure- 

 ments, but to discuss their degree of precision and 

 to criticise systematically every experimental result. 

 With regard to the use of hypotheses, M. le 

 Chatelier is no less decisive. He dispenses with all 

 hypotheses relating to the constitution of matter. 

 These hypotheses, he says, can render great service 

 to a trained mind that will use them as tools, to be 

 cast aside when they are no longer useful; in the 

 instruction of young minds they are dangerous, as 

 tending to imprecision, which is the most redoubtable 

 enemy of science. Too often one comes to believe 

 firmly in these products of imagination, to bandage 

 one's eyes and blind oneself to the most evident ex- 

 perimental facts. When we see what has become 

 of the two fluids of electricity, of the projectiles of 

 the emission theory of light, of the india-rubber mole- 

 cules of Berthollet, of the indivisible atoms of Dalton, 

 we have a right to entertain some anxiety about the 

 future in store for ions and electrons. 



The text of M. le Chatelier's book is a verbatim 

 report of his first course of lectures on general 

 chemistry in 1907-8, given at the Sorbonne, where he 

 occupies the place of Moissan. Probably few chemists 

 would care to have their wisdom offered to the world 

 in this way, and it is to be hoped that few will do 

 so. But it is not too much to say of this particular 

 case that one can only rejoice in the author's lack 

 of time to give the book the revision which he con- 

 templated, for its supreme value lies in the reflection 

 it gives of the living teacher. It is a good deal 

 to say of a book on chemistry that it is human, at 

 least in any other respect than in being tinged with 

 error, but M. le Chatelier's book is human in ex- 

 hibiting, not only the mind, but something of the 

 personality of one of the greatest contemporary 

 chemists, and assuredly of a very exceptional and 

 inspiring teacher. 



The aim of the book is to use carbon and some of 

 its inorganic compounds as a vehicle for imparting 

 the essence of modern chemistry. The chapters bear 

 the following headings :— Henri .Sainte-Claire Deville— 

 Moissan ; propriet(^>s physiques et chimiques ; com- 

 bustibles ; chauffage, pouvoir absorbant, allotropie; 

 carbures m^talliques; acide carbonique ; carbonates 

 metalliques; oxyde de carbone ; combustion des 

 melanges gazeux; origines de la chimie ; resumed des 

 lois de la mecanique ; lois de la mecanique chimique ; 

 lois pond^rales de la chimie; poids mol^culaires et 

 pcids atomiques ; d(5termination exptVimentale des 

 poids mol^culaires. 



The treatment of these topics is in accordance with 

 NO. 2064, VOL. 80] 



the general principles which have already been in- 

 dicated. The choice of carbon as the central subject 

 is, of course, arbitrary. It may be defended on 

 several grounds, and doubtless it may be criticised 

 on others, but it must be remembered that M. 

 le Chatelier lays down no law about such choice. 

 It is the method and spirit of the treatment that are 

 all-important, and in choosing carbon the author 

 brings himself into the region where his own re- 

 searches have given him quite exceptional knowledge 

 and authority. We feel that we are reading some- 

 thing altogether different from the compilations to 

 which we are so inured, and that the author is im- 

 parting what he has made his own. It is for this 

 reason that it is impossible in the present notice to give 

 any adequate idea of the quality of the book. 



No doubt there is much left out in the way of facts 

 that many people would consider very important, but 

 M. le Chatelier has boldly faced a problem that con- 

 fronts everv teacher, and has refused to carry on the 

 burden of teaching all that convention sanctioned a 

 generation ago along with the vast accumulation of 

 new things that have since come to light. Much of 

 the old matter of chemical books and chemical lec- 

 tures has become relatively unimportant, and may well 

 be left to take care of itself. Nowadays a man may 

 be an excellent chemist, and withal profoundly ig- 

 norant of cadmium and its compounds, of the various 

 formulae proposed for bleaching powder, of the 

 methods of analysis of German silver, and of a 

 thousand other things which were the common stock 

 of his immediate scientific ancestors. 



The criticism, exhortation, and censure to be found 

 in M. le Chatelier's book are no doubt primarily 

 addressed to his own countrymen, but they are ap- 

 plicable elsewhere. Perhaps more has been" done than 

 M. le Chatelier implies to alter the form and sub- 

 stance of introductory university courses of chemistry. 

 Prof. Ostwald's " Inorganic Chemistry " and Prof. 

 Alexander Smith's recent work are, perhaps, the most 

 notable books indicative of a movement that is prob- 

 ably existent in many university centres, but to judge 

 from examination papers the old order still largely 

 prevails. 



There is no doubt a national genius which 

 exhibits itself in science as in other domains of 

 thought and action. M. le Chatelier's book displays 

 this scientific genius of his country in its classic form. 



" Les ims," he says, " ne trouvent h la v^rit6 toute 

 sa grace que lorsqu'elle est paree d'orn^ments k la 

 mode du jour, d'autres pr^ferent admirer sa fifere 

 beauts degagee de tous voiles. A chacun la liberty 

 de prendre sa joie ou il la trouve." 



The Frenchman, with a language incomparable for 

 expository uses, can tell us the plain truth without 

 the chill that is associated with our own "dry light." 

 He is apt, perhaps, to lay a little disproportionate 

 weight on the achievements of his own countrymen, 

 and this tendency appears in M. le Chatelier's book 

 to an extent that may provoke some readers. But 

 in all other respects there can be no question that 

 a strict fidelity to facts characterises the book from 

 cover to cover. Arthur Smithf.li.s. 



