184 RESKAECHES UPON THE CHEMICAL PROPERTIES OP GASES. 



Potassium permanganate acidulated with sulphuric acid. Quickly bleached. 



Potassium permanganate crystals in concentrated sul- Prompt oxidation to carbon dioxide. 



phuric acid. 



Potassium bichromate acidulated with sulphuric acid . . No change of color, cold or at 100<^. 



Osmic acid Quickly reduced, with separation of metal as a black 



powder. 



Potassium rutheniate Quickly reduced, with separation of metal. 



Ferric chloride No change, cold or at 100°. 



Calcium hypobromite containing excess of lime water. . No precipitation of calcium carbonate, and hence no 



oxidation to carbon dioxide. ^ 



Potassium ferricyanide Unchanged. 



Bromine water Rapid but incomplete absorption. 



Peroxide of hydrogen No oxidation to carbon dioxide. 



2. Reactions at High Temjyeratures. 



Silver oxide is reduced by ethylene with simultaneous formation of silver car- 

 bonate at 140° (Darvidowa, Ber., 1888, p. 442, R). Palladium chloride (dry) is 

 reduced at about 140°. Iodic acid is reduced with liberation of iodine at about 270°. 



Comments. — As is well known, bromine vapor and ethylene combine to form an 

 oily liquid by the reaction so characteristic of the olefine group. Winkler (Fres. 

 Zeitschr., 1889, p. 269) has shown that the absorption of ethylene by bromine is 

 incomplete, and that the contraction in volume is by no means proportional to the 

 volume of the ethylene present. 



I have tried experiments upon C2H4 from alcohol and from ethylene dibromide 

 (by the action of zinc powder) and the results show that a considerable residue of 

 hydrocarbon remains unabsorbed after prolonged contact with bromine Avater in sun- 

 light. The residual gas, on being mixed with air and passed over ignited oxide of 

 copper, gave carbon dioxide and water at the outset. 



The reaction between ethylene and palladium chloride in solution is of the second 

 class and complete, the gas being rapidly absorbed. Palladium is deposited as a 

 black powder, but no trace of oxidation to carbon dioxide occurs. The reaction is 

 almost the same in the cold and at 100°. The gas escaping fi'om the palladium 

 chloride solution (after complete reduction to metallic palladium) produces no pre- 

 cipitate in lime water. The reaction between palladium chloride and ethylene leads 

 to the production of aldehyde (a study of the changes here involved is yet in hand). 

 Of especial interest in this connection is a statement by Berthelot, that ethylene is 

 oxidized to aldehyde by the action of chromic acid solution at 120° (Compt. Bend., 

 Vol. CXYIII, p. 334). 



Gold chloride produces a similar result, the metal being slowly reduced. As in 

 the case of palladium chloride, no carbon dioxide is formed. 



