3G ARGOX, A NEW CONSTITUENT OF THE AT.MOSl'llERE. 



The ai'ciiiacy uf this iiistiuiiieiit has fi't'ijueiitly been tested ; but fresh expei-i- 

 ineiits were made with air, carbon dioxide, and hydrogen, so as to make certain that 

 reasonably reliable I'esults were obtainable. Of these an account is here given. 



To compare these results with those of {)revious observei"s, the follow iiiu: numbers 

 were obtained for carbon dioxide : Cazin, 1.291 ; Rontgen, 1.305 ; De Lucohi, 1.292 ; 

 Muller, 1.205; Wiillner, 1.811 ; Dulong, 1.339; Masson, 1.274; Regnault, 1.268; 

 Amagat, 1.299; and Jamin and Richard, 1.29. It appeals just to reject Dulong's 

 nund)er, which deviates so markedly from the rest ; the mean of those remaining is 

 1.288, which is in sufficient agreement with that given above. For the ratio of the 

 specific heats of hydi-ogen, we have : Cazin. 1.410; Rontgen. 1.385 ; Dulong, 1.407 ; 

 Masson, 1.401; Regnault, 1.400; and Jamin and Richard, 1.410. The mean of 

 these numbers is 1.402. This number apjjears to differ considerably from the one 

 given above. But it must be noted, first, that hydrogen is difficult to obtain per- 

 fectly jMire ; second, that the wave-length w Inch should have been found is 74.5, a 

 numbei" differing but little from that actiiallv found ; tliiid. that the waves were 

 long and that the nodes were somewhat difficult to place exactly ; and fourth, that 

 the atomic weight of hydrogen has been taken as unity, whereas it is more likely to 

 be 1.01, if oxygen, as was done, be taken as 16. The atomic weight 1.01 raises the 

 found value of the ratio to 1.391, a number differing but little fr(.)m the mean value 

 found I)}' other ohservers. 



Having thus established the trustworthiness of the method wc pioceed to de- 

 scribe our exi)eriments with aigon. 



Five series of measurements weic made with the saiiii)le of gas of density 

 19.943. It will be rcmendicred that a previous detci'mination with the same gas 

 gave as its density 19.904. The mean of these two nundieis was therefore taken as 

 correct, viz., 19.923. 



The individual measurements are: 



for the half wavelength. Calculating the ratio of the specific heats, the number 

 1.653 is obtained. 



