( 31 ) 



Measured : Calculated : 

 a: h = (100) : (010) =* 89^217; — 



a. c = (100) : (001) =- m 29\/; — 



h: c = (010) : (001) =* 82 46\/; — 



p.a = (1Ï0) : (100) =*■ 46 36 — 



c:o = (001) : (ill) =* 48 42 — 



o:p = (111) : (110) = 51 43 (circa) 52" 1' 



c-.p^ (001) : (IlO) = 100 29 (circa) 100 43' 



Cleavable towards jOlOj ; Groth and lioDEwur did iiol find a 

 distinct plane of cleavage. 



Spec. Gr. of the crystals = 2,356, at 8° C, the equiv. vol. = 119,27. 



Topic Axes: / : tf' : to = 5,2365 : 4,6304 : 5,4166. 



Although the analogy of this isomer with the two other triclino- 

 isomers is plainly visible, the value of a : h is here quite different. 

 In accordance with this, the derivative melting at 847/ loivers the 

 melting point of this substance. A mixture of 877o 1-2-4- and 137^ 

 1-2-0- Xitrodihromobenzene melted at 56*^. There seems, however, to 

 be no question of an isomorphotropous mixing. 



D. Nitro-2-6-Dibromobenzene. 



Structure: CgHj (NOj)(i) , Br(2) . Br(6); 

 m.p. 82°. 



Recrystallised from alcohol the compound 

 generally forms elongated, brittle needles 

 which are often flattened towards two 

 parallel planes. 



Monoclino-prlsinatic. 



a:h:c = 0,5678 : 1 : 0,6257. 



|J = 83°24'. 



Forms observed: ^=:|010|, strongly pre- 

 dominant; (i = \0\l\ and o = |lll| about 

 equally strongly developed. The crystals 

 are mostly flattened towards b with incli- 

 nation towards the a-axis. 



