Notices res pec tin If New Books. 027 



were the same as for air, &c. The largest nuclei produced 

 by the discharge are negative ions. 



* Some rough measurements were made on the comparative 

 values of the potential required to give a discharge in air, 

 hvdrogen, and helium. The following results were obtained 

 with a given platinum point : — 



Air. Hvdrocren. Helium. 



+ 1850 ^750 1200 volts. 



-1600 1500 800 „ 



The electrometer used was not suitable for accurate 

 measurements, but it showed sufficiently plainly that the 

 minimum potential in helium w^as a great deal less than thut 

 for the other gases u^ed, and differed more from values 

 for the diatomic gases than these differed among themselves. 



Mv best thanks are due to Professor Thomson and Mr. 

 C. T. R. Wilson for the generous advice and assistance 

 which they have given me. 



LXXVIIl. Notices respecting New Boohs. 



La Compressihilite des Gaz Reels. Par L. Decombe, Docteur es 

 Sciences. Paris : C. Xaud. 1903. Pp. 99. 

 TN this monograph, 'w hich forms Xo. 21 of the " Scientia " series, 

 the author gives a very full and up-to-date account of what is 

 known regarding the compressibility of gases. We regret to see 

 Chapter 1., which deals with the experiments relating to moderate 

 pressures, headed " La Loi de Mariotte." The author gives refer- 

 ences to the publications of both Boyle and Mariotte, mentioning 

 their respective dates, but throughout the chapter never con- 

 descends to give Boyle the credit of his discovery, and persists in 

 speaking of " la loi de Mariotte." Chapter 11. deals with the 

 behaviour of gases under very high, and Chapter III. under very 

 low, pressures. In Chapter lY. is given a very interesting account 

 of the experimental researches relating to the variation of the 

 curve connecting the product jo . v with p at different temperatures. 

 Chapter Y. deals with the critical point, and Chapter YI. with the 

 characteristic equation of a gas. In Chapter YII. is given an 

 outline of the theory of corresponding states, and the concluding- 

 Chapter YIII. is devoted to gaseous mixtures. Numerous refer- 

 ences to original papers greatly enhance the value of this 

 monograph. 



Principles of rnorganic Chemistry. Bi/ Harky C. Joxes, Associate 

 Professor of PJu/sical Chemistry in the Johns Hophins University, 

 >'e\v York: The Macnillan Company. London : Macmillan & 

 Co., Ltd., 1903. Pp. xx-|-o20. 



Tnn author of fhis work is already well known as one of the mo:it 



