196 RESEARCHES UPON" THE CHEMICAL PROPERTIES OF GASES. 



Silver nitrate A 10 per cent, solution quickly coagulates to a while, 



curdy mass. The precipitate dissolves on boiling or 

 on addition of ammonia. A very delicate reaction. 



Ammoniacal silver nitrate Unchanged. 



Iridium chloride Unchanged in the cold ; at 100^-^ iridium is precipitated. 



Rhodium chloride Unchanged. 



Potassium rutheniate Slowly reduced. Black precipitation of metallic ru- 

 thenium. 



Cerium dioxide dissolved in dilute sulphuric acid Unchanged. 



Potassium permanganate Quickly turns brown. ^ 



Potassium permanganate in dilute sulphuric acid Quickly bleached. 



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

 phuric acid. 



Mercuric chloride Dense white precipitate. Very delicate reaction. 



Potassium bichromate acidulated with dilute sulphuric Unchanged in color, 

 acid. 



Osmic acid Reduced. Metallic osmium is deposited as a black 



powder. 



Ferric chloride Decided reduction to ferrous chloride. 



Calcium hypobromite Allylene is oxidized to carbon dioxide. The fluid grows 



milky. 



Lime water and hydrogen peroxide Unchanged. 



Potassium ferricyanide Unchanged. 



Iodine dissolved in potassium iodide solution Unchanged. 



Cuprous chloride in excess of ammonia Canary -yellow precipitate, changing slightly to greenish 



yellow on contact with air. Soluble in acids, with 

 liberation of allylene. 



Mercurous nitrate White precipitate. 



2. Reactions at High Temperatures. 



Experiments were tried in the reduction of certain metallic oxides, but the re- 

 sults are not of sufficient importance to be detailed here. 



Comments. — The reactions of allylene closely resemble those of acetylene. As 

 regards intensity, scarcely any difference can be found. The colors of the palladium 

 compounds of acetylene and allylene do not differ materially. Towards ammoniacal 

 cuprous chloride the two gases exhibit very characteristic differences as regards the 

 color of the resulting compound. The copper allylide is easily soluble in dilute 

 hydrochloric acid. Ammoniacal silver nitrate yields a gelatinous precipitate with 

 acetylene but is not changed by allylene. Oxidation of allylene to carbon dioxide, 

 as in the case of acetylene, is not easily effected except by the most powerful oxidiz- 

 ing agents, such as calcium hypobromite or potassium permanganate in concentrated 

 sulphuric acid. Although the allylene copper compound is rapidly formed in an 

 ammoniacal cuprous chloride solution, the absorption of the gas is singularly incom- 



