Saag eae 
7 ‘tas 7 
Ef. A. Hill—WNotes on Argon and Helium. 371 
The refraction equivalent of nitrogen as given by Mr. 
Deeley is 4:1 and on the theory (which has many who seem to 
favor it) that argon is an allotropic form of nitrogen with 
formula N*, the corresponding value of the equivalent would be 
about 2°2 as against 4:1 required, so that this theory does 
not seem to be sustained. Assuming that the ratio 1°65 
has been correctly determined, notwithstanding the criticism 
of Dr. Stoney, then the anomalous value of the rotational 
energy (disregarding the questions raised by Col. Basevi) seems 
to be associated in argon with an equally anomalous value 
of its refraction equivalent, and the question at once arises 
whether there is any connection between them. 
Nature (July 18, 1895, p. 278), in discussing Mr. C. J. 
Reed’s classification of the elements, makes a somewhat plausi- 
ble suggestion worthy of consideration should the theory of 
monatomicity be sustained. ‘It is remarkable,” says the 
editor, “‘that if helium has the atomic weight 4 it falls natu- 
ae gt? ee er bles? Vasey Ades ee Ro 
rally in this group” (viz: Be gl oe 20 cae 28 gg 29 io 28 
ae , all of which elements, if existent, can be classed as belong- 
ing in Family VIII), “and that its atomic weight deduced 
from the observed density, is somewhat greater than this num- 
ber. If this difference should be due to the presence of some 
small quantity of element 84, then the spectroscopic evidence 
leading to the conclusion that argon and helium contain a com- 
mon constituent would be explained.” This theory assumes 
the monatomicity of both gases but places A = 36 between 
Cl = 35°5 and K = 39, which position is in no way inconsistent 
with the periodic law. 
Thus density of helium = 2°13 and X2 = 4:26 instead of 4. 
'- Peareome— 19") “and 2 —='39°S8 cg 36. 
The excessive densities being due to presence of the heavier 
element 84.* 
I also have worked for some years on a classification of the 
elements, but like many others who have worked along similar 
lines I have been withheld from publication owing to the 
uncertainty surrounding the atomic weight determinations, 
the evidences that there were yet many undiscovered elements 
unknown to science, and the feeling that in such work, where 
the tendency to stray away into mere numerical speculation 
was very great, and where error was so likely to occur from 
the use of unreliable and imperfect data, the time was not 
yet fully ripe, and that the case was one where it was best to 
make haste very slowly. 
* That helium is a mixture of several gases is now pretty well settled, and 
there is some evidence that argon is a mixture also, but not as conclusive. 
