240 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
34°67 ; 84:06 ; 34:27 ; 34:39; 34:00; 34:00; 34:13; 34:20; 34°20; 34:33; 34°33. 
1252 110022 TOSSOXs LO Sis eOsOrelIsOy seW ese elie ele AS arn Gn mmleicca 
With argon the mean is also that of 11 readings, of which the highest is 31°83, 
and the lowest, 31°5. They are :— 
Biles 3 Biles SG g silleyay Bsilesys) S sleg¢ Ss shilesh 3 Ghltsiess Biles s Bileso) 2 Bil-eC- 
HIPS TIS ANS a Oe lly GMs eS 8 Files? 3 TilewH? 2 Wi -wl®, 
If the atomic weight of argon is identical with its molecular weight, it must closely 
approximate to 39°9. But if there were some molecules of A, present, mixed with a 
much larger number of molecules of A,, then the atomic weight would be corres- 
pondingly reduced. Taking an imaginary case, the question may be put :—What 
percentage of molecules of A, would raise the density of A, from 19:0 to 19°99? A 
density of 19°0 would imply an atomic weight of 38°0, and argon would fall into the 
gap between chlorine and potassium. Calculation shows that in 10,000 molecules, 
474 molecules of A, would have this result, the remaining 9526 molecules being 
those of Aj. 
Now if molecules of A, be present, it is reasonable to suppose that their number 
would be increased by lowering the temperature, and diminished by heating the gas. 
A larger change;of density should ensue on lowering than on raising the temperature, 
however, as on the above supposition, there is not a large proportion of molecules of 
A, present. 
But it must be acknowledged that the constancy of the found value of R is not 
favourable to this supposition. 
A similar calculation is possible for the ratio of specific heats. Assuming the gas 
to contain 5 per cent. of molecules of A,, and 95 per cent. of molecules of A, the 
value of y, the ratio of specific heats, would be 1°648. All that can be said on this 
point is, that the found ratio approximates to this number ; but whether the results 
are to be trusted to indicate a unit in the second decimal appears to me doubtful. 
The question must therefore for the present remain open. 
ADDENDUM. 
April 9. 
It appears worth while to chronicle an experiment of which an accident prevented 
the completion. It may be legitimately asked, Does magnesium not absorb any 
argon, or any part of what we term argon? To decide this question, about 
500 grms. of magnesium nitride, mixed with metallic magnesium which had 
? 
remained unacted on, during extraction of nitrogen from “ air-nitrogen,” was placed 
in a flask, to which a reservoir full of dilute hydrochloric acid was connected. The 
