( 761 ) 



formula of comm. N". 95 § G, but they were based on the separate 



readings of the hydrogen-thermometer, because the latter must also 



serve as points of the isotherms. From the above mentioned formula 



dt 



— was determined, and bv the aid of this factor the reduction was 



aw 



effected . 



The difference of temperature for which the reduction was made 

 amounting to less than (). C :J, this method of calculation is perfectly 

 sufficient; only for the temperature of — 135\71, where the difference 

 amounts to 4°, another correction of 0.°01 was required. 



In the subjoined table 1 ) the method of calculation has been repre- 

 sented for one determination of the temperature. The first column con* 

 tains the observed resistance W } in the following column ^represents 

 the resistance at which the resistance-thermometer has been compared 

 with the hydrogen-thermometer (of comm. N°. 95'' Table I §6), and 

 T represents the corresponding reading of the hydrogen-thermometer. 



From the value — — and W — W c follows now the temperature-correct- 

 or 



ion tit which is to be added to T e in order to give t x on the hydrogen- 

 thermometer-scale. 



§ 7. The measurements. 



At the beginning and the end of every series the normal-volume 

 was determined in the way described in Comm. No. 78 § 12, only 

 with this difference that in the series mentioned here every deter- 

 mination of the normal-volume was supplemented with a reading in 

 the £/-tube b. 2 and one of the barometer. In this way two determi- 

 nations were generally made before and after every series. The values 



found before and after every series, differ nowhere more than 



2000' 



The tables V and VI are analogous to the tables VII and VIII of 

 Comm. N°. 78. In the former the results are represented referring to 



l ) The difference of the numbers in this table with those of the Dutch text is 

 due to an improved calculation. The influence of this improvement enters also in 

 some numbers of the last part of this communication. 



