1869.] Action of Bromine upon Ethylbenzol. 125 



deliver a minute stream of air-bubbles, and thus to prevent the violent 

 "bumping" which almost invariably occurs during ebullition in vacuo-, 

 the supply of air may be regulated at will by increasing or diminishing the 



pressure of the screw-clamp on the caoutchouc tubing. This little device 

 succeeds admirably ; it is due to my friend Mr. W. Dittmar, who has 

 already applied it in the distillation of sulphuric acid : so rapidly and effec- 

 tually does the " water-pump " of Bunsen exhaust, that the minute amount 

 of air passing through the liquid, and serving to maintain it in regular 

 ebullition, is without appreciable effect upon the manometer. The flask 

 is attached, as represented in the figure, to a long tube 0, made preferably 

 of thin glass, so as to allow the condensation and cooling to take place as 

 rapidly as possible : over the end of the condennser slides a short length 

 of wider glass tubing, which is fastened air-tight on to the condenser by 

 an inch or two of caoutchouc tubing ; the other end fits into a caoutchouc 

 cork adapted to the receivers ; on this short piece of wider tubing another 

 piece of glass tubing is fixed at right angles, in order to connect the entire 

 apparatus with the caoutchouc tubing leading to the " water-pump." The 

 mode of using the apparatus hardly requires description ; it will be self- 

 evident to anyone familiar to the working of the Bunsen pump. 



Distilled in a partial vacuum (about 05 m.) in the apparatus above de- 

 scribed, the bromide boiled nearly constantly at 148°-152°, and left scarcely 

 any residue of styrolbromide or metastyrol. The bromide thus obtained 

 is a heavy colourless liquid, possessing the characteristic penetrating odour 

 peculiar to all the aromatic substitution products in which the substitution 

 has occurred in the lateral group ; its vapour is extremely irritating, and 

 excites a copious flow of tears when incautiously inhaled. When heated 

 with solution of ammonia or potash in alcohol, it gives up its bromine with 

 the greatest facility. 



The monobromethylbenzol, C 6 H 4 Br{C 2 H 5 , described by Fittig, is a 

 colourless aromatic-smelling liquid, possessing the sp. gr. 1*34, boiling 

 constantly at 199° C, and capable of being distilled without decomposition. 

 It may be boiled or heated in sealed tubes for any length of time with al- 



