F. W. Clarke on the Atomic Volumes of the Elements. 317 
pig the same atomic volume as in the liquid state, viz., 5:5. 
f we calculate the specific gravities of cerotene, C,, H,,, and 
upon the basis of this value for hydrogen, 
or 
get for the first the sp. gr. 0°846, and for the second 0-848. 
The specific gravities actually found for these bodies, as given 
in Weltzien’s “ Systematische Zusammenstellung,” are respect- 
ively 0'861, and 0-890, a variation in the first case, of only 
oo and in the second case of 0-042, from the calculated 
valnes, 
Having thus compared the atomic volumes of many elements 
with each other, a question which now naturally arises, is, how 
far are the relations which have been found, significant, and 
how far are they accidental. i 
In work of this kind, great caution is necessary, for a slight 
prejudice in favor of the kinship of two elements might often 
lead one greatly astray. Thus, gold, silver, aluminum, and 
indium, possess almost exactly the same atomic volume, about 
10:2, and yet no. direct chemical relations are known to connect 
them, and they seem to belong to four different metallic groups. 
i Probably of a similar nature is the seeming relation between 
zinc and the platinum metals. Yet in spite of these dangers of 
error, some of the relations which are found between the 
atomic volumes of certain elements, cannot but be considered 
as deeply significant. The series of relations which I regard 
as fully made out, are the following: The multiple series of 
the alkaline metals ; the series formed by oxygen, sulphur, se- 
allotropic forms of an element, we find no distinct relations at 
all | te this be found to hold true, it will be plain that tt 
different properties possessed by the same element in diiteren 
