Chemistry and Physics. 



67 



chemistry rests. Only in the final chapter of this part is the 

 notion of the atom introduced. Part II is arranged in accord- 

 ance with a modification of Mendeleeff's Periodic System. 

 Graphic symbols are freely used, and ionic terminology has been 

 employed, although the extreme developments of the idea of free 

 ions have not been made use of. Careful introductions to group 

 characteristics, and full summaries covering the relations in 

 detail, are given in this part of the book. h. l. w. 



6. Spectroscopic Analysis of Gas Mixtures. — Many investi- 

 gators have endeavored to use the sensitive portion of the positive 

 discharge in a G-eissler tube as a qualitative means of determin- 

 ing proportions of gases in mixtures. Secchi, however, found 

 that oxygen of air could not be detected in this way. E. Wiede- 

 mann has shown that mercury vapor masks the hydrogen and 

 nitrogen spectra even when a large proportion of these gases are 

 present. Collie and Ramsay found the method inoperative in the 

 case of some gases. J. E. Lilienfeld, by suitable forms of tubes 

 and proper arrangement of electrical circuit, finds that the method 

 can be made extraordinarily sensitive, and gives the following 

 table : 



Smallest visible 

 quantities. 



Collie 

 and Bamsay. 



E. Wiedemann. 



Lilienfield. 



He in N 

 Ar in N 



1ST in Hg 

 H in Hg 



10$ 



37$ 



approx. 30 </ 

 " 30 <f 



O'lfo 



0.932 i 

 (in air) 



0-7$ 

 7$ 



The author shows that the theory of ionization explains the 

 masking of the spectra of gases in a mixture. The presence of 

 one gas prevents the dissociation of another gas. — Ann. der Phys., 

 No. 5, 1905, pp. 931-942. J. t. 



7. The Fitz Gerald- Lor entz Effect. — FitzGerald and Lorentz, in 

 reference to Michelson and Morley's experiments on the drift of 

 the ether, suggested that the dimensions of the apparatus might 

 be modified by its motion through the ether. Professors Morlet 

 and Miller have, therefore, taken up the experiment anew and 

 conclude their paper as follows : " We may declare, therefore, 

 that the experiment shows that if there is any effect of the nature 

 expected, it is less than the hundredth part of the computed 

 value. If pine is affected at all, as has been suggested, it is 

 affected to the same amount as sandstone, If the ether near the 

 apparatus did not move with it, the difference in velocity was 

 less than 3*5 kilometers per second, unless the effect on the mate- 

 rials annulled the effect sought. Some have thought that the 

 former experiment only proved that the ether in a certain base- 

 ment room was carried along with it. We desire to place the 

 apparatus on a hill covered only with a transparent covering, to 

 see if an effect could be there detected." The authors propose to 

 make this experiment. — Phil. 3fag., May, 1905, pp. 680-685. j. t. 



