( 463 ) 



the spacial figure given by Dr. Smits in his fig. 5. His three-phase strip, 

 which I will rather call two-phase strip because it is formed by the 



^^s 



^ 



lines indicating tiie liquid and vapour existing by the side of the 

 compound, assumes tlie form of tig. 4, in which the particular points 

 of the threephase line fig. 3 with vvbicii tliis figure corresponds are 

 indicated by the same letters. The line is extended so far that it also 

 includes the maxima T and T,, and so shows in which respects it 

 differs from the case correspojiding with tig. 2, and of which the 

 strips have been indicated by Smits in his fig. 2. 



If the minimum in the liquid-gas surfaces should be very little 

 pronounced, another type of the three-phase line may be expected, 

 which is represented in lig. 5 in which both minimum and maximum 

 ha\^e disappeared in branch HD, the whole line having the character 

 of branch \h. 



In fig. 4 this would result that beyond the point 0" vapour and liquid 

 lines keep on a downward course, which may be the case if the 

 composition of L and 6r, which coexist with the compound, shifts 

 but little with the temperature so that the increase in pressure which 

 would occur owing to the shifting towards the side of B is more 

 than compensated by the decrease in pressure caused by the fall 

 in temperature. 



Up to the present not a single example has been studied where 

 a three-phase line of the type fig. 3 or 5 made its appearance. Still 

 it is not difficult to see that both must frequently exist in the case 

 of dissociable compounds with sufficient volatility of the two com- 



