514 



NATURE 



[June 15, 191 1 



Ijestive essay is his applicution to the peoples of this 

 far-eastern island of terms such as "Alpine," 

 "Adriatic," "Iberian," "Cro-Magnon," and others, 

 which are not without objections even when applied 

 to the population of Europe, but become doubly mis- 

 leading when applied to Filipinos, who are partially 

 hybridised with real Iberians. 



G. Elliot Smith. 



?RO¥. GROTH'S CHEMICAL 

 CRYSTALLOGRAPHY. 

 Chcmischc Krystallographie. By P. Groth. Dritter 

 Teil, Aliphatische und hydroaromatische Kohlen- 

 stofTverbindungen. Pp. iv + 804. (Leipzig: W. 

 Enj^elmann, 1910.) 



DESPITE the duties appertaining to a professorial 

 chair and the unremitting labour attaching to 

 the editorship of his flourishing Zcitschrift fiir Krys- 

 tallographie und Mincralogie, Prof, von Groth pro- 

 ceeds steadily and rapidly to the completion of the 

 great task he has set before him. The successive 

 volumes have appeared at intervals of two years, and 

 now, four years since the publication of the first, we 

 welcome the issue of the third and penultimate volume. 

 It includes the various aliphatic and aromatic com- 

 pounds that have been obtained in crystallised form, 

 and meets a widely and long-felt want. Putting aside 

 a few oxalates which occur in nature, it has hitherto 

 been impossible to turn up readily the crystal char- 

 acter of any of these substances ; even the most com- 

 prehensive text-books on organic chemistry rarely de- 

 fine the forms more exactly than as being plates or 

 needles. 



The volume is composed of two parts, of which 

 the first is by far the longer. In it the paraffins and 

 the corresponding olefines are grouped together accord- 

 ing to the number of carbon atoms in the molecule, 

 the concluding chapter being devoted to the ureas 

 and the derivatives of uric acid. In the second part 

 the hydrobenzol derivatives and the terpenes and 

 camphors are considered. For each substance the 

 physical characters are stated tersely, but as com- 

 pletely as possible, the information including the melt- 

 ing point, the specific gravity, the morphological 

 characters — the axial ratios, the indices of the obser\-ed 

 forms, the values of the principal interfacial angles, 

 and the directions of cleavage, if any, illustrations of 

 crystals possessing features of exceptional interest 

 being given — and the optical characters — the principal 

 refractive indices for light of various standard wave- 

 lengths, the nature of the refraction, the relation of 

 the optical indicatrix to the crystalline symmetry, and 

 the optic axial angle; the authority for the data is 

 recorded, and references to the original papers are 

 given in footnotes. Each section is prefaced by a 

 brief but interesting discussion of the substances dealt 

 with and the relations subsisting between them. The 

 book closes with two complete indices; in one the 

 substances are arranged alphabetically by their names, 

 and in the other by their formulae in ascending order 

 of the number of carbon atoms in the molecule. Little 

 difficulty should therefore be experienced in tracing 

 any particular compound. It is abundantly clear that 

 NO. 2172, VOL. 86] 



every effort has been made to keep the book as frt* 

 from errors as possible ; in a work of this kind 

 racy is everything. 



The name of the publisher is sufficient guarantee Jo; 

 the excellence of the printing, which is, in fact, beyond 

 criticism. 



APPLICATIONS OF PHYSICAL CHEMISTRY, 

 (i) Themen der physikalischen Chemie. By Prof. 



E. Baur. Pp. iv+113. (Leipzig: Akademische 



V'erlagsgesellschaft, m.b.H., 1910,) Price 4 marks. 

 (2) Das chemische Glcichgewicht auf Grand mechan- 



ischer Vorstelltingen. By Prof. H. v. Juptner. 



Pp. v + 367. (Leipzig and Berlin: B. G. Teubner, 



1910.) Price II marks. --• 



THE two volumes here noticed are not text-books 

 of physical chemistry in the ordinary sense. 

 They deal with selected parts of the subject, and are 

 distinguished by the prominence given to its technical 

 application. 



Prof. Baur's book contains the substance of a series 

 of vacation lectures delivered in the Brunswick Poly- 

 technicum at the instance of the Society of German 

 Engineers. The lectures are models of clear exposi- 

 tion, and are invariably terse and to the point. The 

 experimental illustrations, directions for the repetition 

 of which are included in the text, are well chosen, and 

 calculated to stimulate inquiry. After a preliminary 

 lecture on the principles of modern physical chemistry, 

 the author proceeds to discuss such varied matters as 

 voltaic cells, the blast-furnace. Deacon's process, the 

 contact process for sulphuric acid, the production of 

 atmospheric nitrate, catalysis, gas explosions, explo- 

 sives in general, metallography, and colloidal chem- 

 istrv. Students, both of industrial and of pure chem- 

 istry will find much to interest them in the little 

 volume. 



Prof, von Jiiptner's work on chemical equilibrium 

 is based on the following conceptions. The maximum 

 external work which a chemical process is capable of 

 performing is a measure of the chemical affinity of 

 the process. This work can be measured by the gas 

 pressures of the substances concerned. Hence 

 chemical processes may be treated as mechanical, one 

 substance being pumped into another (production of 

 a compound) or being pumped out of another (do- 

 composition of a compound). Thus dissociation 

 phenomena may be considered as being at the root 

 of all chemical processes. If the dissociation-pressure 

 curves of all compounds are known, the behaviour o; 

 the compounds when they are brought together ma> 

 be predicted ; those with greater dissociation pressures 

 will be decomposed, those with smaller dissociation 

 pressures will be formed. The process will come to 

 an end when the partial dissociation pressures of the 

 common product {e.g. oxygen pressures of oxides) 

 become equal. 



Proceeding on these principles, the author considers 

 the equilibrium conditions in systems with solid, 

 liquid, and gaseous phases. As the book is intended 

 in the first instance for practical men engaged in 

 chemical industry, it is characterised by a wealth of 



