490 



NA TURE 



[September 12, 1907 



joint, such as an ordinary hing^e, and then the points 

 of difference between such a joint and an organic 

 joint. In a hinge the form of the surfaces in con- 

 tact is practically constant, as the joint moves 

 between its extreme positions. This is rarely the 

 case, of course, in a living joint. The variations 

 introduced by these changes are carefully considered, 

 the diagrams aiding very materially in the treatment. 

 The mathematics employed requires some knowledge 

 of differential and integral calculus, and also of 

 coordinate geometry, but presents no very serious 

 difficulties. 



The succeeding part of the book is of great interest, 

 as it contains a description of Prof. Fischer's own 

 methods of showing graphically the movements of 

 single joints and of combinations of joints. There have 

 been many advances in this direction since the Webers, 

 so far back as 1830, investigated the variation in the 

 position of the centre of gravity of the bodv in walking 

 and running. M- Marey introduced photographic 

 methods, somewhat resembling modern kinemato- 

 graph work. The method described in the present 

 work is the best yet devised. A man is clothed from 

 neck to feet in black, and a series of Geissler tubes, 

 eleven in number, are arranged symmetrically on his 

 head and limbs. These are joined to the secondarv of 

 a Ruhmkorff coil, the primary of which is interrupted 

 about twenty-five times per second. The man 's move- 

 ments are then recorded photographically by means 

 of cameras placed on either side and in front and be- 

 hind. In this way records in three directions in space 

 were obtained, and these were coordinated by means 

 of networks of squares photographed at the same time. 

 The phases of movement, either of the whole body or 

 of a single joint-system such as the arm, are thus 

 illustrated. 



Prof. Fischer brings much originality into his treat- 

 ment of a by no means easy subject. The publication of 

 this handbook may well direct the attention of English 

 students to a branch of anatomy which has been 

 somewhat neglected, but in which there remains much 

 to be done. 



GAS AJ^XLYSIS. 

 TraiU pratique de V Analyse des Gaz. By M. Berthelot. 



Pp. ix + 483. (Paris: Gauthier Villar's, 1906.) Price 



1/ francs. 

 T N that branch of chemical analysis dealing with 

 J- gases there is by no means the superabundance 

 of text-books characteristic of other branches of ana- 

 lytical work, and it is noteworthy that such works as 

 we possess are nearly all memoirs of original work 

 by the author, or have been developed from that form. 

 The names of Bunsen, Winkler, Hcmpel, and Travers 

 occur in this connection, and the present work is no 

 exception. In some of his earliest researches, M. 

 Berthelot was met with the necessity of devising 

 methods for the analysis of gases, and many of the 

 methods described in this book were used by him 

 as early as 1858. After an introduction, the work is 

 divided into five sections dealing with the collection 

 and storage of gases, methods of qualitative analysis, 

 NO. 1976, VOL. 76] 



general methods of quantitative analysis, monographs, 

 and the recognition and estimation of single gases 

 and mixtures. 



The whole book is strongly impressed with the 

 author's individuality, and a considerable proportion 

 of the section dealing with qualitative analysis is ori- 

 ginal, especially the chapters on the pyrogenic ana- 

 lysis of gases and spectroscopy. In the latter connec- 

 tion, a simple apparatus is described by means of which 

 a spectroscopic examination of a gas at the ordinary 

 atmospheric pressure can be rapidly made, and in the 

 section dealing with the properties of each gas in 

 detail a table of the chief lines observed by this method 

 is given. The actions of the electric spark and the 

 silent discharge are also special to the author, and his 

 methods are expounded in detail. The remarks on 

 the use of absorbents are worthy of close attention, 

 it being rightly pointed out that the reduction of volume 

 by treating with a given absorbent cannot be taken 

 as a proof that a particular gas is present : a gas 

 must be isolated in a pure state before its presence in 

 a gas mixture can be taken as proved. On the quan- 

 titative side more exception can be taken to the 

 methods expounded, which, indeed, leave much to be 

 desired, both on the score of rapidity and precision. 

 Water jackets are not used for the measuring vessels, 

 the temperature being controlled by immersion in a 

 large mercury trough holding from 16 to 20 litres, 

 and this is described as " the essential instrument 

 in all exact manipulations relating to gases and their 

 analysis." .As this trough requires about 600 lb. of 

 mercury to fill it to its working level, exact gas ana- 

 lysis would of necessity be confined to a very limited 

 number of laboratories if this dictum were to be 

 accepted. The sections on mercury pumps, calibration 

 oT measuring vessels, and determination of gaseous 

 densities are also entirely out of accord with present- 

 day standards of accuracy. References to other 

 workers in the same field are rare, and the description 

 of their apparatus and methods not always accurate. 

 The account given of Hempel's gas burette and its 

 use on p. 26q is an example of this. The commence- 

 ment of the description is that of the Hempel burette, 

 but the figure and manipulation correspond to a modi- 

 fied Winkler gas burette, and Prof. Hempel would 

 hardly recognise the description of his pipette as 

 "formed of two bulbs connected by a fine tube and 

 each furnished with a recurved capillary tube." 



In the fourth section a monograph is given of each 

 gas, and this section will perhaps be found to be the 

 most valuable part of the work. It is a drawback 

 that no references to original memoirs are given in this 

 section, and for this reason it is difficult to make out 

 whether the densities given are experimental or cal- 

 culated, or whether such a figure as —93° C. for the 

 boiling point of propylene is the result of a misprint 

 or an inaccurate observation. 



The book is one which everyone interested in gases 

 should have on their bookshelves, but, like the classical 

 work of Bunsen on the same subject, it cannot be re- 

 garded as of practical service as a text-book at the 

 present day. Its value will be historical and personal 

 as the last published work of a great French chemist. 



