456 M» Berthelot on Acetylene. 



farmed bromide of silver and acetate of oxide of triamylene, 



£15 H so Br2 + 2 G 2 H 3 Ag0 2 =2 Ag Br + <&* ^s^® 2 ', 



and by the action of caustic potash the latter substance is decom- 

 posed into water, acetate of potash, and benylene. Thus : 



Q15U30 ^ 



2G 2 H 3 f0 2 + 2KHO=2G 2 H 3 K0 2 + 2H 2 + G 15 H 28 . 



-* Benylene. 



Kekule, in a paper* on the constitution of the aromatic 

 compounds, developes with great completeness his views of their 

 composition, and he describes a number of experiments which 

 have been suggested by these views. Among his results is one 

 of general interest, namely a method of obtaining from benzole 

 and its homologues the acid corresponding to the next higher ho- 

 mologue : thus from benzole, G 6 H 6 , by the addition of carbonic 

 acid, he obtains benzoic acid, G 7 H 6 O 2 . In the case of benzole 

 the method was as follows. Bromobenzole, G 6 H 5 Br, was dissolved 

 in benzole, and sodium added in small pieces while a current of 

 carbonic acid gas was passed through the liquid, the whole being 

 heated in the water-bath. When the reaction was complete, the 

 whole was dissolved in water, the oily products (consisting of 

 benzole and unattacked bromobenzole and diphenyle, along with 

 benzoate of phenyle and benzophenone) separated by filtration, 

 and the solution precipitated by adding hydrochloric acid. The 

 acid which was thus obtained had all the properties of ordinary 

 benzoic acid. The reaction is thus expressed : — 



G 6 H 5 Br + Na 2 + CO 2 = G 6 H 5 GO 2 Na + Na Br. 

 Bromobenzole. Benzoate Bromide of 



of sodium. sodium. 



In like manner he obtained from toluole, G 7 H 8 , toluylic acid, 

 G 8 H 10 O 3 ; and from xylole, G 8 H 10 , xylylic acid, G 9 H 10 O 2 . 



Berthelot had shown that most organic compounds exposed to 

 a red heat furnished acetylene. He has recently shown f that 

 this hydrocarbon is formed under circumstances equally general : 

 whenever an organic compound is burned in the air and pro- 

 duces smoke, acetylene is produced. The demonstration of this 

 fact may be made by several interesting experiments. 



1. A gas-cylinder containing about 300 cubic centimetres is 

 filled w T ith olefiant gas, a few drops of ammoniacal solution of 

 cuprous chloride introduced into it, and the gas lighted. By 

 inclining the jar and turning it, the solution is spread out on 

 the inside of the jar, and the flame, which at first was only 



* Liebig's Annalen, February 1866. 



f Bulletin de la Societe Chimique, February 1866. 



