592 ON THE RATIO OF THE SPECIFIC HEATS OF SOME COMPOUND GASES. 
column of Table XXXVI. It will be seen that in many cases B/n shows a rough 
approximation to ‘33, but no more. Even allowing for the exaggeration of the 
experimental error by the nature of the equation connecting and y, it cannot be 
said that the intramolecular energy is proportional to the number of atoms in the 
molecule. The paraffins themselves and their monohalogen derivatives show the 
closest approximation, but even in their case the quotient appears to increase as 7 
increases. 
This last fact and the extract below from an article by Professor J. J. THomson 
(Warts, ‘ Dictionary of Chemistry,’ vol. 1, p. 89), suggest another relation among the 
B's that looks more promising. The extract in question is as follows :—‘ Though 
there is strong evidence against the truth of the theorem (7.e., Bourzmann’s Theorem) 
in this form, and the mathematical proof of it is unsatisfactory, yet a very special 
case of it is probably true, viz., that if we have a molecule consisting of 7 atoms 
approximately symmetrically arranged (that is, if the distance between a particular 
pair of atoms is not always very much less than the distances between the other 
pairs), then the ratio of the mean total kinetic energy of the molecule to the energy 
due to the translatory motion of the centre of gravity is proportional to n, the number 
of atoms in the molecule.” 
Tf then the molecules of the gases I have investigated are symmetrical in the above 
sense, we ought to find (8 + 1)/n constant. Looking down the last column of the 
table it will be seen that, though this is by no means the case throughout, yet if we 
confine ourselves to the paraftins and their derivatives that have not more than one 
halogen atom in the molecule, there is a very striking agreement. . 
The mean of the eleven quotients so defined is 493. Methane, as we have already 
seen, falls out of the series, and here it diverges to the extent of 13 per cent., which 
is equivalent to a divergence of about 3 per cent. in y. The y of ethane would have 
to be about 1 per cent. lower to give complete agreement. In the case of all the rest 
the divergence is well within the probable experimental error. 
