CAPILLARY ATTRACTION IN RELATION TO CHEMICAL COMPOSITION. 261 



element chlorine, whose lower value applies to the cases where two 

 or more atoms of chlorine nre closely united together. Of the 

 remaining two abnormal cases, ethylenedibromide and capronitrile, I 

 have no remark to offer. They must be looked upon as genuine ex- 

 ceptions. In the second table the discrepancies are much smaller 

 except in the case of bromine, but the remark made above about this 

 element applies here also. The acids form an important group of 

 exceptions in both tables as well as in Schiffs paper; this is probably 

 owing to the abnormality of their molecular magnitude at the boiling 

 points, and it would be strange indeed if the capillary phenomena 

 did not show an analogous abnormality. 



The atomic capillary constants above given must be regarded as 

 only rough approximations. The values for carbon, hydrogen, chlorine, 



bromine, iodine, etc in the first table may be higher or lower 



than the true values by 50 units, while the difference may be greater 

 in other elements. The values of atomic capillary constants used in 

 the calculation of the second table seem to be much closer to the true 

 values, and may be assumed to be correct within 5 units. A better 

 determination of these constants, or :i better choice of the coefficient of 

 I', may give much better results than have been obtained from the 

 calculations given above. 



The first formula can be applied to the approximate determination of 

 the molecular magnitude of a liquid compound, provided its percentage 

 composition as well as the probable nature of its atomic concatenation, 

 the capillary height (//) for a tube of known internal perimeter at the 

 boiling point, and the specific gravity (/?) at the same temperature 

 are known. Suppose the empirical formula of the liquid to be 



A m B n C p where m', ri, p' may be integral or 



fractional : put this mass .1/ and divide it by p. and designate the 

 quotient by V. Further, suppose the true molecular mass=»M. 



