ee 
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590 DR. J. W. CAPSTICK ON THE RATIO OF THE 
The further investigation of the relations of carbon and silicon would be a 
matter of some difficulty, from the readiness with which the silicon compounds are 
decomposed. 
Corresponding oxygen and sulphur compounds are numerous and stable, but most 
of the sulphur compounds have too high boiling-points to give a sufficiently dense 
vapour at the atmospheric pressure. 
The value of y for sulphuretted hydrogen was got for comparison with that found 
by other observers of water. Experiments made on water vapour have given 
the following results :— 
TaBLE XXXVII. 
: ) | 



t. Y: Observer. 
| 78 1274 | Brym (‘Beibl., vol. 9, p. 503) | 
| 94 1:33 | J&cer (‘ Wied. Ann.,’ vol. 36, p. 165) 
| 100 | 1:321 | Neyrenevur (‘Ann. de Chim.,’ vol. 9, p. 535) | 
103 ; 1277 | De Loccur (‘Nuov. Cim.,’ vol. 11, p.11) — | 
144-300 | 1287 | Counen (‘ Wied. Ann.,’ vol. 37, p. 628) | 


These are very discordant, but some of them seem to be of doubtful validity. 
BEYME made only a single experiment, aud measured only three dust figures. 
De Luccut used CLiment and Dersormes’ method, with a receiver so small that, in 
the light of RontGEN’s experiments, his result is probably too low. NryreNeur and 
Coen both assumed that the vapour obeys Boyue’s Law, the latter observer trusting 
to superheating of the gas to justify the assumption. JAGER alone carried out his 
calculations in a manner that seems allowable, and his result is almost the same as I 
have found for sulphuretted hydrogen. 
The two gases CO, and CS, have widely different values of the ratio of the specific 
heats, so that the possibility of interchange of O and 8 without altering y does not at 
least extend to two atoms. 
It is worth noticing that according to Recnautt’s results the molecular heat 
at constant pressure is nearly the same for the members of any one of the groups— 
H.S and H,O ; (C,H;),8 and (C,H;),0 ; SiCl, SnCl, and TiCl, ; so that it seems likely 
that the laws I have found to hold for the halogens will prove to hold for other groups 
of analogous elements. 
Up to this point, only the relations of the y’s of the gases to each other have been 
discussed, though it is from their enabling us to calculate 8 that the values of y are 
likely to prove ultimately most useful. 
If two gases have the same y, they have approximately the same £, that is, for a 
small rise of temperature the quantity of energy absorbed by the internal vibrations 
of the molecules bears the same ratio to the increase of kinetic energy of translation 
of the whole molecule in the two cases. 
