RESEARCHES UPOlSr THE CHEMICAL PROPERTIES OF GASES. 167 



Expt 33. Osmium Asbestos. — The same mixture of air and trimethylene. Oxi- 

 dation occurred : 



(1) At 200O (3) At 180° 



(2) " 200O (4) " I6.50 



This hydrocarbon seems to stand intermediate between propane and propylene 

 as regards resistance to oxidation. 



11. IsoBUTYLEisrE. — This hydrocarbon was prepared by the action of sulphuric 

 acid upon isobutyl alcohol, by the method of Puchot {Ber., 1883, p. 2284, E). 

 100 gm. isobutyl alcohol were mixed (cold) with 100 gra. oil of vitriol, 160 gm. sul- 

 phate of lime and 40 gm. bisulphate of potash. This mixture was heated, using a 

 flask with reversed condenser, to a temperature sufficient to cause a rapid evolution 

 of gas. Besides butyl ether and other less volatile compounds, impurities in vapor 

 form occur in the isobutylene resulting from this process, which is on this account 

 unsatisfactory. The yield is comparatively large. 



By the action of potash upon isobutyl iodide a much purer product is obtained. 

 Isobutyl bromide may be used instead of the iodide. In either case the use of 

 potash in powdered form greatly facilitates the reaction. Potassium iodide, being 

 more soluble in alcohol than potassium bromide, the alkyl iodide is to be preferred in 

 reactions of the above type, as potassium bromide, resulting from the use of alkyl 

 bromides, encrusts the potash and retards the reaction. 



Isobutylene prepared by the latter method was used in the following experi- 

 ments. It was carefully purified by digestion (cold) with sulphuric acid, and on 

 testing was found to be free from iodine compounds. Isobutylene is soluble in water 

 to a considerable extent and should therefore be collected over salt solution. 

 Mcpt 84. Palladium Asbestos. — 



Isobutylene 3.1 



Air 96.9 



Oxidation occurred : 



(1) At 180O (.3) At 170O (5) At 155>3 



(2) " 160O (4) " 1850 



12. Acetylene. — 100 gra. crushed potash were placed in a flask connected 

 with reversed condenser. A mixture of 50 gm. ethylene bromide with 150 gm. 

 alcohol was added in small portions by a tap funnel. The escaping acetylene was 

 caused to bubble through boiling potash solution and then absorbed by ammoniacal 

 cuprous chloride solution. The resulting red precipitate was washed with ammoni- 

 acal copper solution, then by weak ammonia. After washing, the precipitate was 

 brought into a flask and decomposed by hydrochloric acid, and the acetylene thus 



