ON THE STUDY OF HYDllO-AROMATlC SUBSTANCES. 183 



tlittromofcetrahydrobenzene, tliere being only one possible Avay in which 

 the hydrogen bromide could be eliminated. 



,CH., . CHBr .CH=CH 



CH, \cHBr = 2HBr + CH„ Ncfi 



\CH, . CH, \CH.,— CH 



This reaction has been tried by Baeyer ^ and Fortey.- The lattel* 

 Btates that -when dibroniotetrahydrobenztne is treated with quinoline, 

 dihydrobenzene is formed ; but no details of any sort are given. It 

 is therefore to be presumed the author concluded that the dihydro- 

 benzene so formed was the one giving a tctrabromidc melting at lSi°. 



Preliminary experiments have conclusively proved that such is not 

 the case, for the hydrocarbon so obtained gives no trace of the tetra- 

 bromide melting at 184°, but only the dibromide melting at 101:°'5, thus 

 proving it to be A-'- ''-dihydrobenzene. 



Final experiments, with larger quantities of material are now being 

 cariied out. 



Aromatic Compouiuls derived from Hydro -ciromatic Suhsfdnces. — ■ 

 When dichloro-dihydrobenzene ■* (i) and dichloro-dimethyldihydro- 

 benzene^ (ii) 



.CH = CCl yCH = CCl 



CHj I ^CH CMe, il \CH 



\CH,— CCl \CH,— CCi 



are treated with excess of phosphorus pentachloride, they are converted 

 respectively into metadichlorobenzene and 3 : 6-dichloro-ortho-xylene. 

 Bromine produces the same change with dichlorodihydrobenzene,' two 

 atoms of bromine being tirst added on and then eliminated on distillation 

 as hydrogen bromide. 



it was thought that the reaction would be the same with bromine 

 and dichloro-dimethyldihydrobenzene, a supposition which proves to be 

 incorrect ; for though the aromatic substances obtained are always 

 substituted ortho-xylenes, they consist for the most part of dichloro- 

 bromoxylenes, of which both the possible forms with the chlorine atoms 

 in the 3 : 5 position have been isolated — namely, ." : 5-dichloro-4-bromo- 

 ortho-xylene and 3 : 5-dichloro-6-bromo-ortho-xylene. The work is nob 

 in a sufficiently advanced state to warrant the publication of further detailSs 



Edenvale Caves, co. Clare. — Tleport of the Committee, consisting 

 of Dr. R. F. ScHARFF (Chairman), Mr. R. Lloyd Praeger (Secre- 

 tary), Mr. G. Coffey, Professor G. A. J. Cole, Professor D. J. 

 Cunningham, Mr. G. W. Lamplugh, Mr. A. McHenry, and Mr. 

 R. J. UssPiER, afpointedj to explore Irish Caves. (Dravm vp tnj 

 Mr. R. J. Ussher). 



In April 1902 Dr. Scharff and Mr. R. J. Ussher visited some caves in the 

 CO. Clare, and decided to explore two at Edenvale, near Ennis, which 

 adjoined each other and proved to be connected. 



' Annalen, 1894, 878. "- J.C.S., 1808, 73, 918. 



" J.C.S., 1903, 83, 502. ' J.C.S., 1902, 81, 1531), 



" J.aS., 1003, 83, 502. 



