PAPER BY PROF. BEZOLD. 



261 



TiFi, TiFi^ etc.; in the flgare the orisiu is omitted. We see at once 

 that F2 lies on the straight Hue drawu through Fi and F, and that 



T,l\_T^ F,-T,F, _'nH 



T2T,-%F,-l\F,-nh 



In order now to obtain a decision as to the degree of saturation, we 

 must also introduce into the diagram, as ordiuates, along with the 

 values of ?/i, ?/>, and ys, also the values of y/, y/, and y/, corresponding 

 to complete saturation. The ends of these ordiuates, which are repre- 

 sented by Fi', Ft, and F^' in the diagram, all lie upon a curve that with 

 increasing t rises rapidly, and the equation* of which is 



2/ = 6: 



/^ — U.377 e 



when for (3 we insert the proper constant pressure. 



With the assistance of this equation, or with the approximate for- 

 mula obtained by development, 



, = 023i + 234.8s(iy 



the tables communicated in the appendix [page 287J have been com- 

 puted, by the help of which the curves can be easily constructed di- 

 rectly for the pressures therein considered, and which we can designate 

 as curves of the quantity of vapor needed for saturation at the pres- 

 sure /i [or for brevity, the saturation curve]. 



It will now suffice to cast a glance at the figure in order at once to 

 obtain the following i)ropositious: 



(I) So long as for given temperatures ^i and t^, the values 



~, = Pi and ^^^^z= p.^j remain within given limits, the straight line Fi Fz 

 2/1 y-i 



passes entirely beneath the saturation curve, and therefore tiiere can 

 be no mixiug-ratio for which conden- 

 sation can occur. 



(L*) When pi and pi increase so much 

 that the straight line Fi F2 touches or 

 cuts the saturation curve, as in figure 

 (38), then theie occurs either one or 

 many mixing-ratios that may bring 

 about condensation. 



(3) When ij;i=i?2=100, i.e., when the J^ 

 two quantities of air to be mixed are J^ 

 saturated, then the straight line i^i F^ 

 coincides with the curve Fi' F2', and — . — --^ 

 then for every mixture theie occurs -'/ ■'' 

 super-saturation or coiiden^ntion. fig. 38 



*Hann, Zeit. Oesterr. Genell. Met., 1874, vol. ix, p. '^24. [Smitbson Rep., 1877, p. 399.] 



