6 SATURATED STEAM, AND OTHER VAPORS. 



From these data be calculated, by the aid of seven-place logarithms, the 

 following formula?, which gi\ u millimetres of mercury for 



any temperature in degrees Centigrade : - 



A. 1 team from 32 to C. 



p =* a 4- 6a-. 



a = - 0.08038. 

 log 6 = 9.6021724 - 10. 

 log a = 0.033398. 



n 32 - t. 



B. For steam from to 100* 0. 

 log p = a &a" 4- c/2% 



a = 4.7384380. 

 log 6 = 0.6116485. 

 log c = 8.1340339 - 10. 

 log a = 9.9967*49 - 10. 

 log ft = 0.006865036. 



n = t. 



C. For steam from 100 to 220 0. 

 log ;> = a 6a" -f c/3". 



a = 5,4583895. 

 log 6 = 0.4121470. 

 log c = 7.7448901 - 10. 

 loga = 9.997412127- 10. 

 log /? = 0.007590697. 



n = t - 100. 



D. For steam from 20 to 220* C. 

 log p = a 6a" c/3". 



a = 6.2640348. 

 log 6 = 0.1397743. 

 log c = 0.6924351. 

 log a = 9.994049292 - 10. 

 tog/? = 9.998343862 - 10. 



n = t -f 20. 



aid of the formulae A and B, Regnault calculated and recorded tables 

 of the pressures of saturated steam for temperatures from 32 to 100 C. 

 The formula D was calculated from the data given above for the temperatures 

 - 20 f + 40, 100, 160 C , and 220 C., and was intended to represent the 

 whole range of expcrimrnts. liv this formula, instead of formula C, he 

 calculated the pressures set down in his tables for temperatures from 100 C. 

 to 220 G 



^'ishing to obtain greater accuracy for meteorological work, Moritz re- 

 calculated Equation JB, using ten-place logarithms, aud obtained constants 



