Manchester Memoirs, Vol. Hi. (1908), No. VZ. 3 



experiments, except in those in which arsine was used, 

 as this gas acts directly on solutions of lead and pro- 

 duces stains on paper moistened with lead acetate very 

 similar to the others. This reaction will be referred to 

 subsequently. 



Action of Sclcniiiin on Arsine. 

 {a) In snnligJit. 



The arsine employed was generated in the way 

 described in the paper already referred to, that is to say, 

 a solution of arsenious acid in dilute hydrochloric acid 

 was allowed to drop from a stoppered funnel tube into a 

 gas bottle filled with pure granulated zinc. The exit 

 tube from the gas bottle passed to a wash bottle 

 containing dilute soda, and the exit tube from this 

 passed to a drying tube filled with calcium chloride. 

 The gas so obtained then passed into a tube containing 

 powdered selenium exposed to sunlight. Under these 

 circumstances the selenium became slowly coated with a 

 deposit of arsenic selenide, arsenic being easily detected 

 in the contents of the tube. 



A reaction exactly similar to that occurring when 

 arsine is passed over sulphur exposed to light therefore 

 takes place, although more slowly : 



2 AsH„ + 6Se = AsoSe, + sH.Se. 

 Just as in the sulphur experiments, a secondary reaction 

 was found to take place between the liberated hydrogen 

 sulphide and the arsine, resulting in the formation of 

 arsenic sulphide (which deposited on the glass tube) and 

 free hydrogen, so in the selenium experiment, after 

 prolonged exposure to sunlight, the glass tube was found 

 slightly coated with arsenic selenide, due to the reaction 

 of the liberated hydrogen selenide on the arsine, thus 

 2 AsH„ + sH^Se = AsaSe. + 1 2H. 



