the Umt-Stere Theory. 327 



of CH 2 is thus calculated to be =11-88 + 5*94 = 17*82, while 

 that observed is 17*83 on the average. 



It is however possible, by an independent method, to 

 verify the above numbers for carbon and hydrogen. The 

 volume of hydrogen may conveniently be called the unit 

 stere, and be represented by the symbol S, thus : — 



2S = (V. of C 15 H 32 + V. of C 16 H 34 )-V. of C 3l H 64 = 6. S = 3. 



The average volume of hydrogen obtained in this way 

 confirms that previously found. 



That of carbon is also determined directly as follows : — 



V. of C = 17-83-5*94=ll-89 = 4x2*972 = 4S. 



A similar method based upon the constancy of the volume 

 of CH 2 gives very good results : — 



2S = Vol. of n K 2n+2 -nYoh. of CH 2 ; 

 = Vol. of C 18 H 38 -18x 17*83; 

 = 326*9-320*94 = 5*96. S = 2*98. 

 The conclusion is thus drawn, that the molecular volume V 

 of a normal paraffin of the molecular composition C ?l H 2A+2) 

 in the liquid state, at the melting-point, is given by the 

 formula 



V = (6n + 2)S = WS, 



"W representing the valency number and S the volume of 

 hydrogen. S = 2*970 at the melting-point. 



The above computatiou, which verifies the relation C = 4S, 

 necessarily excludes the following : — C = 2H (Kopp), and 

 C = H (Schroder). Kopp's constant for hydrogen at this 

 point would be 4*398 and that for carbon 8*796 ; so that 

 Vol. of CH 2 = 17*59. Schroder's constant = 5*987 for carbon 

 and hydrogen, and his calculated volume of 

 CH 2 = 3x5*987 = 17*96. 

 Thus, so far as the differences are concerned, it is found 

 that : 



the observed volume of CH 2 17*83 ; 



theoretical C = 4H (Le Bas) .... 17*82,' 



„ C = 2H(Kopp) 17*60, 



C = H (Schroder) .... 17*96. 



In order to further show that the 4 : 1 rule is alone capable 

 of explaining the facts, the following method, which involves 

 no preliminary assumptions, is followed : — 



The volumes are taken just as they stand, and are compared 

 with, say, that of tetradecane. The ratios are then examined 

 in the light of the 4 : 1 rule and of the relations advocated 

 by Kopp and Schroder respectively. a 



