602 Mr. E. Vanstone on the 



It will be noticed that the specific volumes fall as we pass 

 down the series; the differences, however, are exceedingly 

 small, being for the most part in the third place of decimals. 



M 



The values of the ratio ^ , however, rise as we pass down 



the series, the differences being exceedingly small also. 



It is evident then that the stere of Le Bas must be con- 

 stant, since it is the product of two factors which are them- 

 selves nearly constant, but in which one rises and the other 

 falls. 



Le Bas deduces the value of the unit-stere in a second 

 manner : thus, if S represents the stere 



2S = (V of C 15 H 32 + V of C 16 H 34 )-V of C 31 H 64 

 = 6 .-. S = 3. 



If we take 



2V of C 16 H 34 -V of 32 H 66 = 2S = 582-4-576-2 



= 6-2 



•"■ s== 21: 



Again, for carbon Le Bas gives 4 X 2*97 — 11*88, 

 and by the second method 11*89. 

 but 



V of U 35 H 72 -2 (V of Ci 7 H 36 ) = 629-5 -618 = stere for carbon 



= 11-5. 



Hence the value of the stere for H and C depends on what 

 members are taken. 



From what has been said at the outset it will be obvious 

 that the value for the Le Bas' stere for low members of 

 any homologous series will be widely different, since n is 

 small, and therefore the values of a and a' in the quantity 

 (a + 14n)/(a' + 6n) are not negligible. Also we should expect 

 the introduction of CH 2 to cause a more profound change 

 in volume in a small molecule than in a large one. This is 

 shown in the following table. 



The value of the Le Bas' stere is dependent on the relative 

 amounts of increase or decrease of the factors specific volume 



and w . 



In this connexion Le Bas states " The above table shows 

 V 

 that the value for v , r (the stere) for CH 4 is quite discordant 



with the rest of the series. The fact is, however, not of great 

 significance, since the boiling-point of CH 4 is hardly likely 

 to be even an approximately corresponding temperature." 



