188 EF. W. Clarke on Atomic volumes of Liquids. 
0-8, and the third by 1-0 from multiples of the same. Now 
since Kopp does not claim rigid accuracy for his numbers, per- 
haps we may be justified in altering these to multiples of 5°. 
Then for chlorine, bromine, and iodine we shall have the atomic 
volumes 22, 27-5, and 38:5. The last of these, it will be seen, 
is the same number which I deduced from the vapor volumes of 
nine compounds of iodine. The lower number was deduced 
from only three compounds,—the iodids of methyl, ethyl, and 
amyl, whose atomic volumes were determined by actual experi- 
ment. The atomic volume of iodid of methyl, according to 
Kopp, is from 65:4 to 68:3, that of iodid of ethyl from 85:9 to 
86-4, and that of the amyl compound from 152°5 to 1588. If 
now we calculate the atomic volumes of these three compounds, 
we shall find that if we regard iodine as having the atomic vol- 
ume 37'5, we shall get a better agreement with the numbers 
found for the second of these compounds than if we ascribe to 
this element the value 38-5; but in the first and third cases, 
although the lower value for iodine agrees best with the lower 
of the two numbers between which the atomic volume of each 
compound varies, the value 38:5 agrees more nearly with them 
than between those numbers. In other words, we shall get a 
closer agreement with the results of experiment, if we ascribe 
to iodine the atomic volume 38:5, than if we give it the lower 
number obtained by Kopp. 7 
The atomic volumes of seventeen organic liquids containing 
chlorine, have been determined by Kopp. When two values 
Let us now examine some other groups of elements in a sur 
lar manner, 
Since hyponitric acid, replacing as it does, hydrogen atom 
for atom, Se: an atomic volume an exact multiple of a 
e nitrogen group. According to Kopp, nitrogen has 
three atomic volumes ; in eae 23° in Ses sonstiik acid 8'6, 
and in cyanogen, 17-0, | . i 
_ If now we alter the first to 2-15, and the third to 17°2, lea 
ing the second (our starti point) as it is, then the second be 
comes exactly four times the first, and the third just twice the 
gen, let us take this compound as our starti9g =f 
