HYGROMETRICAL TABLES Ixv 



calculated therefrom between the highest temperature at which he made 

 observations, —22.75° C., and —96° C. Below the latter temperature the 

 agreement does not appear so good. Comparisons between Weber's data and 

 the values calculated by means of Thiesen's formula indicate that the latter 

 formula most probably gives values which are slightly too high above —40° C, 

 and slightly too low below that temperature. 



Nernst ^ has also developed a more complicated formula than (5), making 

 use of Pollitzer's quantum-formula for the specific heat of ice. The agree- 

 ment with Weber's data in this case is not quite as good on the whole as in 

 the case of equation (5), and therefore it is not given here. 



More recently, E. W. Washburn - has developed a formula for the vapor 

 pressure over ice, making use of Scheel and Heuse's, and Weber's observa- 

 tional data. Tables computed on the basis of this formula have been published 

 in the Monthly Weather Review - and in the International Critical Tables.^ 

 Formula (5) gives slightly better agreement with the Weber data than does 

 the last formula referred to. Further determinations are necessary to settle 

 the question as to the most representative equation, especially within the 

 range of temperatures between 0°C. and —20° C. Some work has been done 

 by Holborn, Scheel, and Henning * to correct the values of Scheel and Heuse 

 between 0° C. and — 50° C. 



Table 76 has been computed by means of Thiesen's formula (3), from 

 0° C. to —49° 5 C. inclusive, and by means of Nernst's formula (5), from 

 — 50° C. to — 70° C. inclusive. 



The vapor pressures in the cables here given are expressed in standard 

 manometric units. 



TABLE 74. 



Table 74. Pressure of aqueous vapor over ice. English measures. 



The pressure, computed by equation (4) above, are given to 0.00001 

 inch for each degree of temperature from —60° to —15°, for each half 

 degree from —15 to ±0°, and for each tenth of a degree from ±o?o to 

 + 32°o. 



TABLE 75. 



Table 75. Pressure of aqueous vapor over water. English measures. 



This table has been computed by converting Table yy into English 

 units. The temperature argument is given for every o?i from 32?o to 2.1^° () 

 F. The vapor pressures are to 0.0001 inch from 32?o to I30°9 P., and to 

 0.001 inch from i3ofo to 214°^ P. 



1 Nernst, W. Verhandlungen der Deutschen Physikalischen Gesellshaft, vol. 12, 

 p. 568, 1 910. 



2 Washburn, E. W. Monthly Weather Review, vol. 52, p. 488, 1924. 



3 International Critical Tables, vol. Ill, p. 210, McGraw-Hill Book Company, 1928. 

 * Holborn, L., Scheel, K., and Henning, F. " Warmetabellen der Physikalisch- 



Technischen Reichsanatalt," Braunschweig, 1919. 



