(26) 



Crystallography. — "On a new case of form-analogy and misci- 

 bility of position-isomeric benzene-derivatives, and on the crystal- 

 forms of the six Nitrodibromohenzenes.'" Bj Dr. F. M. Jaeger. 

 (Communicated by Prof. A. F. Holleman.) 



(Communicated in the meeting of April 27, 1906). 



§ 1. The following contains the investigation of the crystal-forms 

 exhibited by the six position-isomeric Nitrodibromobenzenes, which 

 may be expected from the usual structure-representations of benzene. 

 It has been shown that, in this fully investigated series, there 

 again exists a miscibility and a form-analogy between two of the 

 six terms. 



The above compounds were kindly presented to me by Prof. 

 Holleman, to whom I again express my thanks. 



This investigation is connected with that on the isomeric Dichloro- 

 nitrobenzenes, which has also appeared in these proceedings (1905, 

 p. 668). 



A. Nitro-2-3-Dibromobenzene. 



Structure: C^Hj . (NO,) .Br .Br ; melting-point: 53^ C. 



(I) (2) (3) 



Tlie compound, which is very soluble in most organic solvents, 



Fig. 1. 



crystallises best from ligrofn -|- ether in small, flat, pale sherry - 

 coloured needles which generally possess very rudimentary terminating 

 planes. 



Triclino-pinacoidal. 



«:/>:C = 1,4778:1:1, 9513. 



A= 90°30' 

 J5= 110°37' 

 C— 90°16V; 



«= 90°45V; 



/? = iio°367; 



y = 89°59\/; 



