45 



TABLE 



OF 



THE ELASTIC FORCE OF AQUEOUS VAPOR, 



EXPRESSED IN MILLIMETRES OF MERCURY FOR CENTIGRADE TEMPERATURES, 



BY REGNAULT. 



THIS table contains the elastic forces of vapor corresponding to every tenth of a 

 degree of temperature between 35 and -|-40 Centigrade, as determined by the 

 experiments of V. Regnault, made by order of the French government, for the 

 purpose of establishing the numerical value of the elements which enter into the 

 computations concerning the steam-engine. These results are generally considered 

 as the most accurate science possesses at present. They are published in the 

 Memoires de rinstitut, Tom. XXI. ; and more correctly in Regnault's Eludes sur 

 VHygrometrie, in the Annales de Chimie et de Physique. In Vol. XV. Regnault 

 gives the table of elastic forces for every tenth of a degree from 10 to -f- 35 

 Centigrade, which is reprinted in Table I. The numbers below 10 and above 

 -|- 35, in the same table, have been taken from another table for every full degree, 

 previously published in Vol. XI. p. 333 of the same periodical, and in the same 

 volume of the Memoires de Vlnstitut, extending from 32 to -j-230. 



It should be remarked, however, that the numbers below zero, in the two tables 

 just mentioned, having been computed from different formulas of interpolation, slightly 

 disagree. In order to establish a continuity, therefore, the numbers in Table I. cor- 

 responding to full degrees from 10 to 35 have been formed by starting from 

 the value due to 10 in the larger table of Regnault, and subtracting from it the 

 difference between 10 and 11 in the other table, in order to find the value 

 of 11, and so on, by subtracting successively the corresponding differences to 

 35. For the fractions of degrees below 10, the mean values have been 

 adopted as sufficiently accurate for meteorological purposes. 



