RESEARCHES UPOlSr THE CHEMICAL PROPERTIES OF GASES. 



185 



Rhodium chloride is remarkably stable towards ethylene (and other olefines) ; 

 after three months' contact with the gas, no trace of reduction was observed. 



Potassium permanganate (in weak solution) has been shown by Wagner {Ber., 

 Yol. XXI, p. 1230) to convert olefines on digestion (cold) into glycols. The reac- 

 tion may serve as a mode of preparing glycols, but could only in exceptional cases 

 be utilized as a gas reaction. 



Chromic acid mixture is said to be reduced by ethylene (Chapman and Thorp, 

 WaWs Die, 1st Supp., p. 602). In repeated experiments I have failed to show that 

 chromic acid undergoes reduction by ethylene, l^o carbon dioxide is formed, the 

 color of the solution remains unchanged, and no absorption occurs on prolonged 

 contact of ethylene with a 10 per cent, solution of chromic acid in a eudiometer. 

 Similar results were obtained in using potassium bichromate acidulated by sulphuric 

 acid. Carbon dioxide could not be detected on passing ethylene through a solution 

 of chromic acid at 100°. 



Potassium rutheniate, an extremely sensitive reagent, loses its orange color rap- 

 idly and deposits metallic ruthenium. 



Peroxide of hydrogen is said by Berthelot to convert ethylene into glycol. This 

 has apparently no significance as a gas reaction. 



The reduction of palladium chloride solution, if not attended by evolution of 

 carbon dioxide, is an evidence of the presence of an olefine (and probably ethylene 

 as the commonest of the olefines) in a gas mixture. 



Sulphuric acid does not absorb ethylene in the cold, but the absorption is rapid 

 at a temperature of 160°. 



PROPYLENE. 



Preparation. — From allyl iodide by the action of zinc (see p. 165). 



1. Reactions in Solution. 



Propylene, in its reactions towards the various reagents, resembles ethylene so 

 closely that no important differences can be mentioned. 



REAGENTS. 



Palladium chloride. 



Platinum chloride solution 



REACTIONS. 



Reduction is prompt and complete, the gas undergoing 

 rapid absorption. If mixed with nitrogen (as an 

 inert diluent) and conducted into lime water, after 

 passing through the palladium chloride solution, it 

 is easily shown that no oxidation to carbon dioxide 

 is produced by the palladium chloride. The same 

 is true if air is used instead of nitrogen. 



Unchanged, cold or at 100°. 



