298 SCIENCE PROGRESS 



made of the simple compounds which have not yet been 

 touched. 1 



Finally, it is to be confidently hoped that a study of the 

 dispersion both of the elements of compounds and their 

 relation to the dispersion of their constituents would be of 

 the highest value. 



The necessary apparatus could be obtained for ^"20 or ^30, 

 and no student who devotes sufficient time to the subject need 

 fear to be disappointed in obtaining results which will certainly 

 be interesting and possibly important. 



1 The following compounds have not been attacked : HF, H,Se, H 2 Te, AsH a , 

 SbH 3 , C n H 2n + 2 , SiH 4 , SiF„ SiCl„ SiBr„ BH 3 , BF S , BCL, BBr 3 ", B(C 2 H 5 ) 3 , CF„ 

 CHF 3 , CH 2 F 2 , CH 2 C1 2 , N0 2 , (N 2 3 ), HN0 3 , NaNH 2 , KNH 2 , NH 3 0, PF 3 , PF 6 , 

 PCU, PBr 3 , PI 3 , P 2 6 , POCl 3) PSC1 3 , H 2 S0 4 . The following ought certainly to 

 be redetermined: SeCl 4 , VOCl 3) SbCU, SnCl 4 , TiCl 4 , HC1, HBr, HI, H 2 0, H 2 S, 

 C 6 H 12 , CH.C1, CHCls, PCL, CS 2 . 



