( 779 ) 



which follows ^r=0.0036618 T, TVc. =273\09and 7'„ M) e C .=373°.09. 

 For the reduction of the data given in Comra. N". 97" to the 



y j 



theoretical normal volume the value -- = 0.99939 was taken, borrowed 



v 



from the determinations of isotherms of Comm. N°. 70 (Schai-kwijk). 



The values of B\ and />" 10l , have been derived from the same 



determinations of isotherms 1 ) by the aid of the pressure-coêfficienl 



0.0036629 (see XV at the end of this Communication), neglecting 



the correction to the absolute scale for 20°. These values are: 1 ) 



B\ = 0.000607 B\ 00 = 0.0006G4 



The values of B't were found from the VII. H 3 . 1 already 

 more fully discussed in § 1, which gives in a reduced form 3 ) 



10 s $ = + 173.247 r - 4G2.95C — 706.416- 4- 384.2458 - — 4.2530- 



t t s t 5 



whereas VII. 1 gives: 



10 s $ = 157.9500 t — 305.7713 — 231.8247 97.5686 - — 4.2530 - 



r t' t 6 



From this the values of B't have been calculated for the standard 

 temperatures of the isotherms. 



The subjoined table contains in the first column these standard 

 temperatures t s measured on the scale of our hydrogen thermometer, 4 ) 



the limiting value 0.0036608. The same value as was found above from nitrogen, 

 was derived by Berthelot (loc. cit.) from Chappuis' results for nitrogen and those 

 for hydrogen obtained with a thermometer-reservoir of hard glass. In the same 

 paper be derives the value 273°.08 for the absolute zero-point for the case that 

 also the less concordant results found by Chappuis for hydrogen with a platinum- 

 thermometer are taken into account. Afterwards (see Zeitschrift für Elektrochemie 

 N°. 34, 1904) the first mentioned value 273°.09 is again found by taking the 

 mean of the above values for nitrogen and hydrogen, and those which may be 

 derived by means of the experiments of Kelvin and Joule. 

 x ) Compare the conclusion of § 10 of Comm. N°. 97". 



2 ) The values found by Chappuis are resp. 0.000579 and 0.000606. 

 Those of Witkowski are 0.000616 and 0.000688. 

 Those derived in Comm. N°. 71 from the 



observations of Amagat are 0.000669 and 0.000774. 



3 ) According to Dewar, pK= 15 atms. and Ta'=29° are used for the calcula- 

 tion, which also served for the derivation of VII. 1. 



Further have been put Aao = 0.99939 and A A~ Aao (1+0.0036618*:). 



4 ) The slight differences with the value of table XII of Comm N°. 97« are 

 due to a correction (sec XV) in consequence of the application of' the improved 

 pressure-coefficient 0.0036629 and the influence of the dead space on the deter- 

 minations of the temperature, which will' be more fully discussed in the last part 

 of this communication. 



53 



Proceedings Royal Acad. Amsterdam. Vol. IX. 



