(474) 



93i 7o Benzylaniline + 64 "/„ Azohenzene, t = 35° C. 



88 7„ „ 12 "/„ „ ^ = 32r C. 



48,67„ „ 51,47» „ t = 49° C. 



23,77„ „ 76,37„ „ ^=:61i°C. 



On crystallisation of the two compounds from a joint solution in 

 alcohol + chloroform, small aggregated orange-coloured needles were 

 obtained which were unsuitable for further investigation. But it seems 

 that solid solutions are formed here. 



As regards Azohenzene and Stilhene with which Dihenzyl forms 

 solid solutions, I have tried to determine, in mixtures of the two 

 substances, the points of initial and final solidification in the usual 

 manner. It appeared that these two substances whose isomorphotro- 

 pism is almost indistinguishable from real isomorphism, also agree 

 with real isomorphous substances in this respect that they can form 

 a continuous series of mixed phases from 7„ to 100 7„. The lower 

 branch of the continuously-rising melting point curve is situated so 

 close to the higher one that a sharp determination was quite 

 impossible. 



The following melting points were found : 



Azohenzene melts at QS" C. 



-f 22,9 7„ Stilhene melts at 82°.4 C. 

 + 66,947„ „ „ „ 107°.2 C. 



Stilhene melts at 120" C. 

 The melting point of Azohenzene is therefore raised by addition of 

 Stilhene. The lowering of the melting point of Stilhene is not projwr- 

 tional to the number of molecules of added Azohenzene (incorrect 

 rule of Küster) but takes place more sloirhj. 



The mixed crystals obtained from mixed solutions were homogeneous 

 and of a bright red colour. They crystallise beautifully. The mixture 

 being sublimed the vapour deposits mixed crystals as is also observed 

 by Bruni. 



P'inally, we wish to observe that Hydrazohenzene , notwithstanding 

 the difference in symmetry, shows in its parameters some degree of 

 analogy with Azohenzene if we take = | 211 1, to = | 421 1 and 

 m = 12101. 



Azohenzene : a : h -. c = 2,1076 : 1 : 1,4220 ^ = 76^32'. 



Hydrazohenzene: a -. h -. c ^ 1,9574 : 1 : 1,2497 ^ = 90^ 

 In the case of Diphenylkydrazine, notwithstanding its great simi- 

 larity to the monoclinic system, there is no question of such a 

 distant analogy. 



