RESEARCHES UPON THE CHEMICAL PROPERTIES OF GASES. 183 



HEPTANE. 



Heptane obtained from theoline (see p. 161) was found to have the same general 

 chemical properties as methane. Even cerium dioxide, osmic acid, gold chloride and 

 potassium permanganate are unaltered by prolonged contact with the liquid hydro- 

 carbon. Heptane seems in fact to be almost, if not quite, as stable as methane 

 towards reagents in solution. 



The paraffins as a group are, in the main, so proof against reactions that we can 

 do little more than remove all other hydrocarbons by suitable reagents and then 

 test for paraffins by combustion over oxide of copper to carbon dioxide and water. 

 This, of coarse, leaves the nature of the individual paraffins undetermined. 



Spongy palladium, heated in air so as to become partially converted to palla- 

 dium oxide and transferred to an atmosphere of methane or other paraflSn, undergoes 

 a reduction. The reduced metal then combines with the carbon of the hydrocarbon 

 (Graham and Otto, Yol. Ill, p. 995; Wilm, Ber., 1892, p. 220). This carbide heated 

 in air or oxygen yields carbon dioxide. The production of carbon dioxide in this 

 case may be utilized as a test for hydrocarbons in a gas mixture, provided no free 

 oxygen is present. The carbide of palladium, formed by the above method, dissolves 

 in aquaregia (containing but little nitric acid) with a camphor-like odor. 



OLEFIlSrES : ETHYLENE. 



For preparation, see p. 161. The method of Erlenmeyer and Bunte was used. 

 It is necessary for the purpose of studying its reactions to purify the gas from traces 

 of alcohol and ether vapor by prolonged digestion with sulphuric acid. 



1. Reactions in Solution. 



REAGENTS. UEACTIONS. 



Palladium chloride . , Quickly reduced, the metal appearing as a black pow- 

 der. No carbon dioxide is formed. 



Platinum chloride Unchanged. 



Gold chloride Extremely slow reduction, the gold appearing as a brown 



powder. No carbon dioxide. 



Gold chloride in excess of potassium hydroxide Extremely slow reduction. 



Iridium chloride Unchanged. 



Ruthenium chloride After prolonged contact (several days) the solution is 



bleached. No deposition of metal occurs. 



Rhodium chloride Unchanged. 



Silver nitrate Unchanged. 



Silver nitrate in ammoniacal solution Unchanged. 



Potassium permanganate, neutral solution Quickly turns brown. 



