RESEAECHES UPOlSr THE CHEMICAL PROPERTIES OF GASES. 193 



yields carbon dioxide and in the case of ethylene yields no carbon dioxide. In both 

 cases reduction of the palladium salt occurs. 



(2) Ammoniacal silver nitrate is unaltered by olefines up to and including Cj, 

 but is reduced to metallic silver and ammonium nitrite by CO. 



(3) Platinum chloride yields carbon dioxide, but is not immediately reduced to 

 metal by CO. With C2H4 no change occui-s. 



(4) Rhodium chloride is slowly reduced by CO, but is unaltered by C2H1. 



(5) Ruthenium chloride is bleached by carbon monoxide without reduction to 

 metal. Upon ethylene it exerts no action in the cold, but at 100° is slowly bleached. 

 1^0 precipitation occurs in either case. Like palladium chloride, it converts ethylene 

 into aldehyde, especially on warming to 100°. 



Among olefines, isobutylene is distinguished by its reducing action upon cerium 

 dioxide and by its absorption of iodine in solution, the color of the latter being 

 bleached. 



Trimethylene, which is a saturated hydrocarbon, cannot be properly included 

 among olefines although isomeric with them. It is especially distinguished from 

 the olefines proper by its stability towards neutral potassium permanganate and 

 towards osmic acid. In almost all cases the reactions of trimethylene are much 

 slower and less complete than those of the olefines. 



ACETYLENE. 



This hydrocarbon was prepared by the action of alcoholic potash upon ethylene 

 dibromide (see p. 167). The method of preparation proposed by Berthelot (Ann. Ch. 

 Phys. (5) X, p. 365), by causing a Bunsen burner to " strike back," although appli- 

 cable for coal gas, has not given satisfactory results when natural gas was used. 



1. Reactions in Solution. 



REAGENTS. REACTIONS. 



Palladium chloride Reddish-brown precipitate. No reduction occurs. Very 



sensitive. 



Platinum chloride Unchanged, cold or at 100°. 



Gold chloride Immediate reduction. Intensely black precipitate of 



gold. No carbon dioxide formed. 



Gold chloride in excess of potash No change cold ; trace of reduction at 100°. 



Silver nitrate White precipitate. Very delicate reaction. 



Ammoniacal silver nitrate White precipitate, which is so gelatinous that a 10 per 



cent, solution of silver nitrate becomes nearly solid, 



like boiled starch. 



Iridium chloride No change cold ; reduction after one week, or on boiling. 



Rhodium chloride Unchanged. 



Potassium rutheniate Very slow reduction. 



