( 471 ) 



Some tiine ago, Huuni and Ciamician M, and Garklli and Calzolari') 

 concluded, on account of ci'voscoi)ic abnormalities, to a formation 

 of mixed ])hases in the solid stale l)elween, DlhenzijJ, Stilbene, Tolane 

 and Azobenzene, and to the isoniorpkogenous substitution in aromatic 

 molecules of the atomic-combinations: 



— CHj — OH2 — 



— CH = CH — 



— C = C — 



— N = N — 



According to Brum and Gorni''), Beiizylideneaniline: CgHj . CH = 

 N . CgHj may also form mixed crystals with Stilbem' and Azobenzene 

 so that according to them tlie atomic combination : — CH = N — 

 ought to be included in the above series. The question now arises 

 whether the cond)ining forms: — NH — NH — and — CH, — NH — 

 which find in Hydra zobenzene and Ih'nzylamine their most simple 

 representatives, aualogous with the above derivatives, belong to this 

 isomorphogenous series or no. 



The important question, however, arose whether we have really 

 the right to speak here of an isomorphism, as Ave ai-e not allowed to 

 conclude at ojice that an isomorphism exists merely on account of 

 the power of mixing in tiie solid state only. 



BoERis "), hoAvever, demonstrated that the four tirstnamed sub- 

 stances exhibit sucli a close form relationshi[) that this is practically 

 indistinguishable from true isomorphism. 



Dlhenzyl : C,H, . CH,— CH, . C«H,. 



Monoclino-prismatic a\b : c=. 2,()80() 



Mlbene : C«H, . CH = CH . C«H,. 



Monoclino-prismatic d -. b : c =z 2,1701 



7;>Awé^:C«H3.CL-EC.C,H3. 



Monoclino-i)rismatic n -J) -. c = 2,2108 



Azobenzene : C«H, . N = N . C«H,. 



Monoclino-prismatic a : b : c = 2,1076 : 1 : 1,3312 ; /? = 65 34' 

 Here, however, we meet with differences in as]>ect, optical orien- 



^) Bruni and Ciamician, Soluzioni solide e miscele isomorfe IVa i composli a catena 

 aperta saturi e non saUui ; Rendio. Lincei (1899). 8. I. 575; Gazz. Chimic. Ital. 

 (1899). 29. 149. 



-) Garelli and Calzolari, Snl comporiamonto ci'ioscopico di sostanze aventi i 

 cosliliizione simile a qiiella del solvonte ; Rondic. Lincei (1899). 8. I. 585; Gazz. 

 Chim. Ital. (1899). 29. (2). 258; Rendic. Lincei R. Accad. (1900). 9. (1). 382. 



■') Bruni and Gorni, Gazz. Chim. Ital. (1899). 1. 55. 



3) BoERis, Atti Societa Ital. di Sc. Natm-, Milano. (1900). 39. Ill — 123. Abstract 

 Z. f. Kryst. 34. 298. 



