PAPER BY PROF. BEZOLD. 221 



designated hyp, as being- located on the curve of saturation, the equa- 



firm is 



tion is 



Ih—Lh+c 



or R K T 



P*= 



v, 



or finally after substituting the value of v, 



R\+x Rx 



It is therefore easy to determine the correlated values of v s and p s for 

 any constant quantity of moisture x and for any given temperature. 

 On the other hand, only with the greatest difficulty and even then only 

 by the use of empirical formulae is it possible to bring the curve of 

 saturation into the ordinary form :* 



We also will therefore entirely relinquish all attempts in this direc- 

 tion. By so much the more important is it therefore to show that from 

 the curve of saturation for a given value of x one can with ease deduce 

 such curve for any other quantity of moisture. If T and hence also e 

 is constant, then it directly follows from the equation 



R&T 



i\=x 



e 



that the initial abscissas of isotherms corresponding to equal tempera- 

 tures but different quantities of moisture are proportional to these 

 quantities of moisture themselves, or if we indicate by v y and v 2 the 

 initial abscissas belonging to the quantities of moisture x x and j^, we 

 have 



Vi : v 2 =Xi : x- 2 . 



If therefore we have any point such as Ni of the dew-point curve S t 

 corresponding to a given temperature Tthis will be the initial point of 

 the isotherm (T, x } ) if as in the above given manner we indicate the 

 point corresponding to the temperature T and the quantity of vapor 

 a?ij now draw the isotherm (T, x 2 ) for the same temperature T but for 

 another quantity of vapor x 2 , then we have only to increase or diminish 

 the abscissa of Ni in the ratio x 2 : #1 in order to obtain the x 2 of the 



* We see this from the following consideration: Since according to equation (4) 

 e=<p (p s , x), and since again e=F(T), and moreover T—if) (p„ x); since further the 

 equations (3) and (4) give v s jj s =(i?A+Jci?6)T, therefore v s p s — (E\+xBs) . ip(p t , x), 

 or if we omit x from under the functional sign as heing oonstant, 



v. 2> s =(fiA+£jRs). rp(p,) 

 an equation which contains only v s andp,, hut not explicitly, as variables. 



