Chemistry and Physics. 397 



disappeared, but there is no difficulty in finding them here. For 

 instance, the reaction of hydrogen sulphide upon heated copper 

 is given as H 2 S 4- Cu = CuS 4- H 2 , whereas it is very well known 

 that Cu a S would be formed ; it is stated that lead tetra-acetate is 

 a yellow salt, instead of a colorless one ; and there are several 

 errors in connection with metallurgical topics. h. l. w. 



6. A Manual of Qualitative Chemical Analysis / by J. F. 

 McGeegory. 8vo, pp. xiv, 133. Boston, 1903 (Ginn & Com- 

 pany). — This text-book has been prepared to meet the wants of 

 the author's own classes, as has usually been the case with the 

 great number of books on this subject that have already appeared. 

 Their number shows the existence of much diversity of opinion 

 in regard to the best methods of teaching this branch of chemis- 

 try. The book under consideration gives a rather extensive 

 course in the reactions of the radicals, and it seems that all of 

 these are expected to be mastered before their analytical applica- 

 tion is taken up. The learning of all these details without apply- 

 ing the knowledge and thus connecting it with analytical pro- 

 cesses, is an exceedingly difficult matter, and it appears to the 

 reviewer that this feature is objectionable. The attempt to 

 avoid purely mechanical work on the part of the student by 

 omitting tabular outlines of methods is praiseworthy. The fol- 

 lowing sweeping statement in the introduction leaves no place 

 for the elements themselves, nor for the many "simple" inor- 

 ganic substances which are neither acids, bases, nor salts : "Every 

 simple inorganic substance consists of two parts. The first, 

 which is a metal or positive radical, is chemically combined with 

 the second, which is a non-metal or negative radical." The book 

 is marred by the so-called reformed chemical spelling, which 

 leads to incorrect pronunciation and is not in harmony with the 

 rest of the English language as it is now written. h. l. w. 



1. Influence of Temperature and Pressure on the Absorption 

 and Diffusion of Hydrogen by Palladium. — The following con- 

 clusions have been reached by Gr. N. St. Schmidt : The absorp- 

 tion of hydrogen by palladium follows the phenomena of most 

 absorbing substances above 140° C. That is, it increases with the 

 pressure and diminishes with the temperature. The diffusion 

 increases with the temperature and with the pressure. 



This is not true under 140° C. Here enters an irregularity. 

 We are accustomed to consider that in the course of diffusion of 

 a gas through a solid body that first adsorption takes place, then 

 absorption, then diffusion. Diffusion then can only take place if 

 the gas is in the first place adsorbed by the solid body ; and this 

 happens only when a certain affinity exists. We must, therefore, 

 assume that under 140° C. no affinity exists between hydrogen 

 and palladium. This enters first at higher temperatures and with 

 it adsorption. There are analogies in chemistry : for instance, 

 carbon and nitrogen do not combine at ordinary temperatures ; 

 but at high temperature form CN. 



Am. Jour. Scl— Fourth Series, Vol. XVII, No. 101.— Mat, 1904. 

 27 



