360 EL. A. Hill— Notes on Argon and Helium. 
questioned by C. E. Basevi (Nature, July 4, 1895, p. 291), who 
endeavors to show that the equation P= Por of Clanusius 
should be written § = 3k (y—1), where 8= the number of 
atoms in the gaseous molecule. This latter equation he shows 
gives 2 for the value of § in argon, leading to the conclusion 
that argon is diatomic; the mathematical proof being given in 
full. 
3d. The conclusion also depends upon the correctness of the 
method for calculating the ratio of the two specific heats. 
This ratio, it will be remembered, was obtained indirectly from 
the velocity of sound in argon gas, as determined by the 
“Kundt” dust figures. Dr. G. Johnstone Stoney,* in a paper 
read before the Royal Society, May 20, 1895, doubts the cor- 
rectness of the method employed in this determination, and 
advances proof in support of the position that the ratio 1°65, 
thus determined, is not the true ratio of specific heats; and if 
so it is of course not yet shown that argon gas has no rotational 
energy, and the argument for its monatomicity fails. 
4th. Moreover Prof. B. Brauner remarks:+ “It has been 
shown most ably by Mendeleeff, that the argument derived 
from the relation of specific heats = 1°66 is not absolutely con- 
clusive in favor of the monatomicity of the gases in question 
(argon and helium).t Practically the same point was made 
independently by myself in my previous article (1. ¢., pp. 409- 
410) and also foot note quoting Mendeleeff, whose remarks came 
to my notice after that article was in press. 
Now all of these points may be well taken, or some may be 
sustained and others not, but af any one of them is sustained 
the argument for monatomicity fails. The fact is that mon- 
atomicity seems to most careful thinkers utterly inconsistent 
with the classification of Mendeleeff, as well as all the various 
modifications of it which have appeared from time to time. 
There seems to be a deep-seated feeling that something remains 
to be explained; that the general principles upon which New- 
lands, De Chancourtois, Mendeléeff, Meyer, and the host of 
others have based their classifications, are in the main correct ; 
and that argon fails to find its place in these classifications 
because some of our preconceived notions of the molecule 
need to be modified; and hence the foregoing attempts. At 
any rate, such are the views which impelled me to publish my 
own article on argon and the periodic law. 
* Nature, July 18, 1895, p. 286, and Proc. Roy. Soc., vol. lviii, p. 177. Nature 
gives an abstract only. 
+ Chemical News, June 7, 1895, p. 271. 
t See Proc. Russian Chem. and Phys. Soc., March 2 (14), 1895; Nature, vol. li, 
p. 543, and Chemical News, July 12, 1895, p. 14. 
