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The crystals of the l-SA-5-tribromo- 

 2-Q-dinitro-tohiene are represented in 

 Fig. 5 in the forni in which they 

 crystalHse from a mixtnre of carbon 

 disulphide and ' benzene. The quadra- 

 tical looking plate-like crystals, deposited 

 from benzene only, exhibit nearly the 

 same forms ; in their case, however, the 

 form a is very i)redominating ; then 

 follows c, wdiilst the other forms are 

 narrow and little developed ; moreover 

 the form q is always and o often 

 absent. I also occasionally obtained 

 from benzene, thick prismatic crystals 

 with a, h and c and even o. 



TrldüiO-plnacoïdal The axial rela- 

 tion is: 



Fig. 5. 



a : b ■ c = 0,5322 : 1 : 0,9581 



« = 88^21'. A = S^'26'. 



|Jr=95°4'. ^ = 95° 2'. 



y = 90°58'. C'=:90°50'. 



Forms observed are : a = jlOOj, and b = |010| eqnally strongly 

 developed, a generally more Instrons than 6 ; c ==_|00 J | very liistrons; 

 = |T22| well developed and lustrons ; u> = |112| smaller than o 

 but very lustrons; q=\0i2\, small and less conspicuous; m = rJlOj, 

 narrow, but broader than p=z jllOj, which form is often present 

 Avith a single plane ; .v' = f344| very narrow and not properly 



1) If, in view of llir symbol of s' wc nilliei- choose o = \-2V6\, u — \±2'ó\ 

 s'= |343j, whilst retaining the' other symbols, we get a : b : 6 = 0,53:22 : 1 : 0,7186, 

 which agrees better with the other two isomers. 



