( .^84 ) 



Hence we have t'ov .-r ^ \'^ : 



//' thci-c is ii, iidnbnuin critical temperature, then also .ï, ^.i^ i^but 

 not necessarily rice versa); it' not x^'^ x-^, then there is )?o minimum 

 of 7'.i. (Again the reverse need not be true). 



If jr should be •< '/i' ''lei ne'rer x, >.ei, while T,,- is only minimum, 

 when (3) is satisfied, viz. if tt^'/,,. But this exceptional case, viz. 

 that for S'^l the value of :nc remains below 7^, will be very rare. 



ll appears therefore convincingly from the above, that the two 

 conditions include each other often, but by no means always. 



Just one example: Mher -{- H^O. 



273 4- 364 195 



Here ^ = = 1,36, jr = = 5,42, [/ji = 2,35. The 



273 + 195 36 



51,0 

 second member of (3) becomes therefore =: —-— ; = 1,39. As therefore 



36,6 



ff <^ 1,39, there will lie a minimum critical temperature, and hence 



also A", >.''i according to the above rule. In fact the second member 



of (5) =1,46, and li being <1,39, so a fortiori (9 < 1,46. 



What is found, is in iiai'niony with experiment, as the three phase 

 pressure was found larger than the vapour pressure of ether. 



Let us now take (',H,-{-HJJ. 



Here the three phase pressure was found smaller than that of 

 0,H,. Let us now examine if the inequality of (5) predicts the same. As 



273 + 364 195 



^=2-73T3T = '^''^ '-' = 4^2- = ^'^^' ^^ = 2,08, so we find 



for the value 1,36. And so 2,07 is «r*/ <' 1,36 now. Here 



2 \/n—l ' ^ 



too the rule holds again. 



According to the above rule there is now not a minimum critical 



35,9 

 temperature either. The second member of (3) becomes now — — = 1,31, 



and 2,07 is still less < 1,31 than <1,36. 



The two examples are illustrations of the first principal type, 

 where a plaitpoint curve runs from C^ to A, and one from C.^ to C\. 



The reader will observe, that vmter serves here as 2"'' component, 

 so a very abnormal substance. But we must bear in mind, that in 

 the neighbourhood of x = 0, where both the rules hold, the liquid 

 phase consists almost entirely of ether (resp. C^H,), so that the water 

 present may be considered as almost perfectly normal on account 

 of the extremely high degree of dilution. 



Foi' the sake of completeness we mention tiiat two other known 

 examples, which with those mentioned are about the only ones 



