( 646 ) 



By determining tlie meltingpoinr line of tlie system of the two 

 substances (tlie aldehyde melts at 45"^, the acid is decomposed at 

 about 200°) the point up to which they are still capable of forming 

 mixed crystals may i)eriiaps be determined moi'c accurately. It is 

 not improbable that in the intramolecular I'cari-angements of other 

 solid substances solid solutions may also be formed; if possible this 

 will be further investigated. 



Chemistry. — "■The transfitnnath}! of (lipIwnyHodon'niin 'uxUilc and 

 chloride and its ndocitf\ Hy Mr. E. H. Hüchxer. (Communicated 

 by Prof. C. A. Lorry dk Bruyn). 



(Communicated in the mcctiug of March 28 1903). 



It is about 10 years ago thai Vktok Mkykr and IIaktmann ^) 

 announced the imporlaut discovery of a new class of iodine deriva- 

 tives, tlie iodoniuni bases, substances with a trivak^nt iodine atom, 

 having about tlie same liasic po^^er as the ordinary alkalis and capable 

 of forming salts. The sim[)lest representative of this interesting 

 class of substances is diphcnyliodoniuin-hydroxide: (0^ Hj), .1 () H ; 

 the sahs, such as the chloride or the nitrate, when dissolved in water, 

 apjieai-ed to possess a con(bicti\e power corresponding with that of 

 the alkali salts'*). 



The behaviour of the halogen salts of the base, when heated, is 

 peculiar; Victor Mkyer and Hartm.vnn noticed tliat on fusing these 

 salts at 175° a decomposition sets in, which s[Huitaneously leads to 

 a complete conversion into halogen-benzene (C^HJ.^ = J — .] = 2 0^11^.} 

 with strong evolution of heat. 



Tiiis transformation now deserved a closer study. It may be con- 

 sidered as a depolymerisation l)ut is distinguished however from 

 many other similar reactions, not only by the great difference in 

 character between the decomposing substance and the products of 

 decomposition but also i)y the fact that the transformation is not 

 reversible. At all events, uj> to the present no process is knimii 

 which leads straight from iodobenzene to di[)henyliodoniumiodide. 

 In this latter respect the above mentioned reaction is distinguished 

 from the transformation with which it has been compared namely 

 that which tetramethylammonium iodide suffers on heating; the latter 

 substance is readily ju-epared from its products of decomposition at 

 the orduiary tem[)erature. 



1) Ber. 27. 502, 1594. (1894). 



2) Sullivan Z. ph. Gh. 28. 523. The salts are, therefore, not dissociated hydrolytically. 



