[ 22 ] 



IV. Chemical Notices from Foreign Journals. 

 By E. Atkinson, Ph.D., F.C.S. 



[Continued from vol. xxiii. p. 478.] 



OF all the carburets of hydrogen, acetylene, C 4 H 2 *, is the 

 most stable. It can be formed from olefiant gas or marsh- gas 

 by the action of heat, or by that of the induction spark ; and it is 

 also formed under the influence of the former agent, from benzole 

 and naphthaline, which have usually been regarded as the most 

 stable carburets. Berthelott has succeeded in preparing this 

 gas artificially by the direct union of its elements. 



Hvdrogen may readily be obtained pure and dry ; but this is 

 not the case with carbon, which usually contains a variable pro- 

 portion of hydrogen. This, Berthelot found, was best removed 

 by the action of chlorine at a high temperature, which has 

 further the advantage of removing sulphur, aluminium, and 

 silicon in the form of volatile chlorides. 



Purified carbon is not acted upon by hydrogen under the 

 influence of the highest heat alone, even when carried to the 

 point of melting the porcelain tube in which the carbon was 

 placed. Nor were experiments made with the induction spark 

 more successful. 



But when the electric arc is formed between two charcoal 

 electrodes in an atmosphere of hydrogen, combination takes 

 place as soon as the spark commences to pass. Acetylene is 

 formed, and is the sole product of the reaction, and its produc- 

 tion continues as long as the electric arc is maintained ; it can 

 be reproduced indefinitely by the same charcoals so long as the 

 transport of matter between the two poles has not entirely dis- 

 aggregated them. 



C 4 + H 2 = C 4 H 2 



Carbon. Hydrogen. Acetylene. 



The acetylene formed around the poles is carried away by the 

 current of hydrogen, and is condensed in an ammoniacal solu- 

 tion of protochloride of copper, producing a red precipitate of 

 cuprous acetylene. 



It is easy to obtain large quantities of acetylene in this way ; 

 under the conditions of the experiment, Berthelot was able to 

 prepare about 10 cubic centims. of acetylene in a minute. 



The compound of acetylene with copper was treated with pure 

 hydrochloric acid, by which acetylene was liberated in the free 

 state; both its analysis and the comparison of its properties 

 identified it. 



* Phil. Mag. vol. xx. p. 196. 



t Camples Rendus, March 24, 1862. 



