the Unit-Stere Theory. 347 



R 

 XX. — Table of Determinations of -~ for the four Hydro- 

 carbons under conditions of identically reduced pressures. 



P / P K- 



5 H 12 ; R D =251. 



C H 14 ; H D =29-7. 



C 7 H 16 ; R 



D =34-33. 



C 8 H 1G ; R 



D = 38-95. 



V. 



K D 



y. 



^ 



V. 



^ 



V. 



R D 





| 



V 





v 





V 





V 



•001474 







... 





145-44 



•2360 



165-39 



■2355 



•005898 







130-51 



•2276 



150-94 



•2274 



17173 



•2268 



•011795 



113-20 



•2218 



133-65 



•2222 



154-58 



•2221 



175-83 



•2216 



•022411 



11613 



•2161 



137-19 



•2166 



158-68 



•2164 



180-51 



•2158 



•04232 



! 120-15 



•2089 



141-95 



•2092 



164-02 



•2093 



187-02 



•2083 



•088465 



! 125-62 



•1999 







171-78 



•1999 



195 84 



•1988 



1-00000 



309-2 



•0811 



366-3 



•0811 



425-7 



•0806 



488-9 



•0797 



Since the characteristic relation between carbon and 

 hydrogen has been found under all corresponding conditions, 

 it is concluded that the molecular refractions themselves are 

 subject to similar additive relations. 



XXI. — Table showing the Values of the Ratio —: 

 for the Paraffin Hydrocarbons. 



No. 



Hydrocarbon. 



Pentane, C 5 H 12 



Hexane, C G H 14 



Heptane. C-H 16 



Octane, C 8 H 18 



Decane, C 10 H 22 



w. 



R D . 



w' 



32 



251 



•784 



38 



29-7 



•782 



44 



34-33 



•780 



50 



38-95 



•779 



62 



48-3 



•779 



It is thus seen that the apparent molecular volumes of the 

 (normal) paraffin hydrocarbons under corresponding con- 

 ditions are approximately equal multiples of their molecular 

 refractions and thus also of their real volumes. The appli- 

 cation of the valency rule to the apparent volumes under the 

 above conditions depends on this fact, although the reason 

 for the proportionality between the real and apparent volumes 

 under corresponding conditions remains unexplained. 



Traube has already studied molecular refractions from this 



point of view, that is, he has shown that the ratio ^~ 



