370 LOlil) 1JAYLKIGI1 ON THE COM POSSIBILITY OF CASKS 



Secondly from CO., and : 



CO 2 = 44-014 



O, = 32-000 



C = 12-014 



Thirdly from CO 2 and CO. This method is independent of the density and 



compressibility of oxygen : 



2CO = 56-006 



CO., = 44-014 



C = 11-992 



It will be seen that the number for C0 3 is too high to give the best agreement. 

 Were we to suppose that the true number for C0 3 was 44'004, instead of 44'014, we 

 should get by the second method 12 '004 and by the third 12'002, in agreement with 

 one another and with the result of the first method. The alteration required is less 

 than one part in 4000, and is probably within the limits of error for the compressi- 

 bility (as reduced to C.), and perhaps even for the density. The truth is that the 

 second and third methods are not very advantageous for the calculation of the 

 atomic weight of carbon, and would perhaps be best used conversely. 



Finally the molecular weight of N 2 O allows of another estimate of that of nitrogen. 

 Thus 



N 3 O = 43-996 



O = 16-000 



N 2 = 27-996, 

 whence N = 13'998. 



It should be remarked that these results relative to CO 2 and N 2 O depend very 

 sensibly upon the correction of a from about 13 C. to C., and that this depends 

 upon the discussion of M. D. BERTHELOT. M. BERTHELOT has himself deduced 

 molecular weights in a similar manner, founded upon LEDUC'S measures of densities. 



It remains to refer to some memoirs which have appeared since the greater part of 

 the present work was finished. Foremost among these is that of M. CHAPPUIS,* who 

 has investigated in a very thorough manner the compressibilities of hydrogen, 

 nitrogen, and carbonic anhydride at various temperatures and at pressures in the 

 neighbourhood of the atmospheric. For hydrogen M. CHAPPUIS finds at C. 

 a = + -00057 per atmosphere, and for nitrogen a = '00043. In the case of 

 carbonic anhydride po departs sensibly from a linear function of p. M. BERTHELOT 



gives as a more accurate expression 



00670 

 po = 1 , 



* " Nouvelles Etudes sur lea Thermomfetres a gaz," ' Extrait du tome XIII. des Travaux et M^moires 

 du Bureau International des Poids et Mesures.' 



