162 RESEARCHES UPON THE CHEMICAL PROPERTIES OF GASES. 



and it has received in the present work a larger share of attention than any other 



gas. 



Ethylene was prepared by the method of Erlenmeyer and Bunte {Ann. der 

 CJiem. u. Pliarm., Yol. CLXVIII, p. 64). The yield is, however, small as compared 

 with the theoretical. The older method of Mitscherlich (Kolbe, LelirK d. Organ. 

 Chem., Vol. I, p. 349), according to which the vapor of boiling alcohol is led into a 

 mixture of 10 parts sulphuric acid and 3 parts water, at a temperature of 165° C, 

 yields more ether than ethylene, although it possesses the advantage that frothing 

 is avoided. Whatever the strength of the sulphuric acid used, there is always pro- 

 duced a large proportion of ether which cannot be absorbed by rapid bubbling 

 through sulphuric acid. Part of this ether vapor is removable by agitation with a 

 large volume of cold water. Its complete removal requires prolonged contact with 

 oil of vitriol. The gas was purified by soda solution containing bichromate of potash 

 and digested with oil of vitriol for several days. 



Ethylene was also prepared by the action of zinc upon CoH^Br^ {J. Ch. Soc. (2), 

 XII). Ethylene dibi'omide dissolved in 2 parts alcohol was introduced by tap fun- 

 nel into a flask containing zinc powder, and connected by a reversed condenser with 

 a gasometer. The same method of purification by sulphuric acid was used as in the 

 preceding case. This method is in every way very satisfactory for the preparation 

 of small quantities of ethylene. 



Sxpt. 19. Palladium Asbestos. — 



Ethylene 3.1 



Air 96.9 



Oxidation occurred : 



a) At 210° (4) At 200° (7) At 224° 



(2) " 180° (5) " 220° 



(3) " 224° (6) " 191° 



The ethylene burns therefore more easily than either methane or ethane. 



PJxpt. 20, Palladium- Platinum Asbestos. — The same mixture of ethylene and 

 air was used. The range of temperatures at which oxidation occurred was about 

 the same as in the case of the preceding experiment, showing that the mixture of the 

 two metals is no more efficient than palladium alone. 



IJxpt. 21,— 



Air 96.9 



Elhylene 3.1 



30 per cent, palladium asbestos was moistened with cobalt nitrate solution, dried and 

 ignited in order to coat the asbestos with peroxide of cobalt. On passing the gas 

 mixture, carbon dioxide was produced at the following temperatures : 



(1) At 277° (2) At 250° (3) At 260C 



