( 764 ) 



ment or' the temperature did not experience any perceptible disturbance, 



on account of which the stability of the bath was the more ensured 

 throughout a whole determination of an isotherm. 



§ 8. Calculation of the observations. 



The calculation is made in the same way as described in Comm. 



N°. 78 § 8. 



For the calculation of the variability of the volume of the piezo- 

 meter-reservoir U l at low temperatures we started from the qua- 

 dratic formula for h found in Comm. N °. 95'^ § 1, so that l\ = 

 23.43 X ' J0_J an<1 *■ — °- 0272 X 1°~ 6 - ^° correction for glass- 

 expansion was required for the volume of the glass capillary U. 2 nor 

 for that of the steel capillary 6 r 3 . For the reduction of the gasvolumc 

 in the glass capillary U t to 0° we proceeded as follows: the volume 

 was divided into 5 parts U 2a , U-n, , U 2c , U 2 d and U 2e . £7^ represents the 

 part in the liquid bath increased by 2 cm. of the capillary above 

 the liquid, where the temperature may still be put equal to that 

 of the bath. Un U 2t and ^2d form together the remaining part of 

 the capillary in the cryostat above the bath, U- 2/j -\- U 2c corresponds 

 to the volume u\ of § 5 of Comm. N°. 95« and Vu to u\. U 2e 

 is the volume of the capillary that is outside the cryostat. For the 

 reduction of the volumes U->b, U 2c and U 2 d we started from the 

 same determinations of the temperature as in Comm. N°. 95*. As on 

 account of the greater density at lower temperatures the mean tem- 

 perature found cannot directly be used for the reduction, each of the 

 above mentioned volumes is divided into 3 parts, the temperature of 

 each of these parts is derived, and from this the mean temperature 



* 



2- 

 T 

 is determined according to the formula t = — -in which T represents 



2- 



T 



the absolute temperature. The coefficients of expansion, which are 

 required for the reduction, were determined by means of the general 

 development into series of Comm. N u . 71 with a slight modifi- 

 cation of the coefficients mentioned there. The results obtained in 

 this way do not give an appreciable difference with those which 

 were found when the reductions are made with the approximate 

 results for the determinations of the isotherms obtained in this way. 

 With regard to the corrections of the temperature of the volumes 

 U s and U i we proceeded in a way similar to that of Comm. N°. 78. For 

 that of the reservoir at low temperature a somewhat different way 



