500 Alexevelf and Beilstein on the Preparation of Zincethyle. 



hand with an air-pump, and on the other hand with a gas-holder 

 of carbonic oxide. It was then several times alternately exhausted 

 and carbonic oxide allowed to enter. When the flask was full of 

 pure and dry gas, it was hermetically sealed and the bulb broken. 

 The bromine vapour made the balloon almost opake ; its quantity 

 was only so much that about one-half of the carbonic oxide could 

 be changed into €9 Br 2 . The flask was then exposed to the sun- 

 light, by which it became somewhat decolorized, but the decolo- 

 rization was not complete even after standing a couple of years. 

 The point of the flask was opened under caustic potash ; a rapid 

 decomposition of the bromocarbonic acid took place. The pro- 

 ducts of this decomposition (carbonic and hydrobromic acids) 

 were absorbed by the potash, and the residue, amounting to one- 

 half of the total, consisted of pure carbonic oxide. Of course, if 

 the flask had contained nothing but its original charge of car- 

 bonic oxide and bromine vapour, this could not have taken place. 



Messrs. Alexeyelf and Beilstein* have still further simplified 

 the method of preparing zincethyle, which the latter chemist 

 devised^in conjunction with Riethf. Instead of the alloy of zinc 

 and sodium, they now use ordinary zinc turnings previously 

 dried over sulphuric acid, but not otherwise specially prepared, 

 and a small quantity of the alloy. For 100 grms. of iodide of 

 ethyle, they take 7 to 8 of alloy and 70 to 80 of zinc ; the opera- 

 tion appears to proceed much more easily, and the yield is 

 always in accordance with the theory. 



On zincethyle these chemists have tried the action of bromo- 

 form ; that of chloroform they had already tried, and found it to 

 be in accordance with the equation 



€HCl 3 4-3Zn€ 2 H 5 =C 5 H 10 + 3ZnCl + € 2 H 6 . 



But the action of hromoform frequently differs from that of 

 chloroform, for instance in the case of sodium-alcohol. When 

 bromoform was dropped into zincethyle the action was very brisk. 

 The products disengaged were passed 'through an artificially 

 cooled tube, and then into a bulb apparatus containing bromine. 

 In the cooled tube some bromide of ethyle was condensed, while 

 the other gases disengaged were completely absorbed by bromine ; 

 and on treating the bromine with caustic soda, an oil was left 

 which was found to be bromide of propylene. Hence the action 

 was probably as follows : — 



€HBr 3 -f-2Zn€ 2 H 5 =G 3 H 6 +G 2 H 5 Br + 2ZnBr. 



Bromoform. Propylene. Bromide 



of ethyle. 



* Comptes Rendus, January 18, 1864. 

 t Phil. Mag. vol. xxiv. p. 306. 



