318 F. W. Clarke on the Atomic Volumes of the Elements, 
compounds cannot be accounted for upon the supposition that 
in one compound the element exists in one allotropic form, and 
in another compound in another, 
One of the most important points to which I have been led, 
By 
solid state, values just half those which they possess as liquids, 
and carbon seems to follow the same rule. 
The exceptions found under zinc and mercury, however, must 
be borne in mind, showing as they do, that the law is not a 
general one. But how far these relations between solids and 
liquids holds true, seems to me a matter of great interest, as 
possibly affording a clue to some general law connecting the dif 
ferent states of aggregation. Ug 
One more point and lamdone. In many cases, even when the 
relations between the elements have been plainest, it has been 
necessary to slightly alter the atomic volumes actually found, 10 
order to bring them in accordance with theory. Some of these 
alterations have been wholly within the limits of experimental 
found for elements, it would be wholly unjustifiable for me 
ascribe the variations from theory to experimental error. An 
late, were determined under dissimilar conditions. Concerning 
the cause of these relations between different elements, I shall 
hazard no conjectures. Not only are our data too incomplete, 
and unfit to form the basis of any theory, but it seems 0 td 
