335 ) 
by prolonging it in the region of the negative w (fig. 2, 4, 8 and 10). 
Equation (34) gives : 
m* 
PT: = PTk + Mo, (Tr — CTI) = PTL — EE RT, vrei ©) 
so that also to the first approximation p7, = pri (comp. equation 27). 
And from the equation (82) we derive in connection with (38): 
UTr = OTE + : eae Se ae: (40) 
AE B m,,(m?,,+RTum,,) RT. WW ez 
from which by comparison with (28) we find 
i m 11 Moy rm rr 
Tr — UTpl = TL ze tm Gers en ee 
The difference vr, — vr, may be positive or negative, that is to 
say the critical point of contact may be situated on the vapour or 
on the liquid branch of the border curve (or of the connodal line). 
In the first case, as it is well-known, we have retrograde conden- 
sation of the first type for all mixtures comprised between «x7, and 
27,1, in the second case retrograde condensation of the second type: 
TST lor, vry; rc. II; figs. 1 Bandd v7,v.¢c. 1; figs.7,9and11 
| p / 
ET or nn beses D, 2, ad zon rpuur.e.1Lfigs.8, LOandl2 
Expressing that the plaitpoint and the critical point of contact lie 
on the connodal line and subtracting the equations thus obtained 
we find to the second approximation : 
1 m?.. m? 
4 Re i ae? Ths d . (42) 
4 RT, Mao (mm? Ng Lait RT m,,) 
this expression is positive if RT, ¢ > m?,, (fig. 14), and negative 
if RP %k,e<{m?,, (fig. 15). In the same way we find by means 
of the border curve 
Ty —_ & 1B lige 
ee Esta wre. (49) 
Erp 4 RT; Mago (aios =~ RT: a Be 
so that Mor Be, 0 et = a 
Pe ihe tn pr < Pz: figs. 5 and 6! | PTr > pm igs. 11 oe 2 
BEEN UL MS, pr > pri; figs. 14 pr oe PTyl; figs. 7 (feat | 
als secs rl | 
(To be continued). 
