( 557 ) 



h'il)r()m()|)lieii(»lhi'(»iniiic by iiicjuih of Icadaccljilc passed iulo 2.() 

 dihrouKXjiiiuoiie, willi .siibsliliilioii of 2 lii' l»y O, lic looked upon il 

 as il dlbi'oiiioqiuiione iji which ojic O is rcphuTd by 2 Uv [llici-efore 

 as il lelrabi-oüH)kGto(bhy(b'()bciizeiie]; hv is of ()|)iiiioii tiial i(s fonna- 

 tioii froiH tribi'oniopliciiol cjui oidy be e\[)hiiiiod bv assiiiniii^- thai 

 tlio latten- can rciict in the tautomeric form of a p-fpiiiioid ketone 

 ilS follows: 



II Br II IJr ir Bi- 



«< ^OII -* Br< __ >() ^ lii/ J>0 



n l}r 11— Bi- U"— iir 



In a pai)er which ;i|)j)eared a year iigo, Kastt,f, ^) has come to the 

 same conclusion as Thiklk, ;is the i-esub of ijivestigations conducted 

 cojijointly with Lokvenhart, Rosa SPEi.iKn and Gilbkkt. Kasti,k has 

 iilso established the fact tliat it is only sulphuric iicid \vhich, e\en ;it 

 the ordinary temperature, is capable of causing the transformation 

 into tetrabromophenol ; a dozen otlier reagents gave a negative result. 

 In oitkn- to explain this specific iiction of suli)huric acid, Kastle 

 assumes the intermediate formation of an additive i)i'oduct of this 

 acid with trii)romopheiu)lbromine ; this at first would lose lUU-j which 

 would tiien again react at once with i-eformation of sulphuric acid 

 iind cause the migration of Hr into the benzene nucdeus. This inter- 

 pretation of the transformatioji requires tlie a[)))earance of two non- 

 isolated iind therefore hypothetical intermediiite [)roducts and of three 

 successixe reactions. 



Mr. 1)FJ-/,KK has no\v studied tlie velocity of Iransfoi-malion of tri- 

 bi-omophenolbromine. Tlie circumstiince that the (irst substance retidily 

 parts with an atom of bromine would ie;ul to expect that its 

 quiintitative estimation would be ])ossible in the |)resenc(> of tetni- 

 bi'omophenol. It now appeared thai the elinnnalion of free iodine 

 from hydriodic acid, also observed by Kasti,k, lakt's |»lace (pianlila- 

 tively ; lribromophenoli)romine may theivfoiv b(^ estimated in the 

 presence of tetrabi-cnnophenol by titration. 



At the commencement of the investigation the belia\ioiii' of the 

 solid substance towai'ds sulphuric acid was ascert;iine<l. If the cr\slals 

 are covered with the ordin;ii-y J)(i per cent ;icid it is noticed th.it 

 they lose their yellow colour iind become opaque ;iiid white; of 

 solution in the acid taking place nothing c;in \)v perceived exen bv 

 the aid of the microsco|)e. No formation of slri;ie can be obserxed; 

 the wliole |)henomenon seems to be ciiiicted within tli(^ solid substance 

 commencing on tiie surtace where the substance is in conl;u't with 



1) Anier. Ch. -I. 27. 31. {i'MH). 



