A. W. Peirce — Existence of Selenium Monoxide. 163 



Art. XX. — On the Existence of Selenium Monoxide j by 

 A. W. Peirce. 



[Contributions from the Kent Chemical Laboratory of Tale University — LIII.] 



It was Berzelius's idea that the odor of decayed cabbage 

 which is noticed when selenium is burned in air is due to the 

 formation of a gaseous lower oxide of selenium which he called 

 the monoxide. The same oxide is said to be formed when 

 selenium sulphide is dissolved in an insufficient amount of 

 aqua regia, in the distillation of a mixture of selenium and 

 selenium dioxide, and in the action of sulphur upon selenium 

 dioxide. 



Sacc* records his inability to obtain such an oxide, and attrib- 

 utes the odor which is noticed under these conditions to a 

 trace of selenium hydride. A very minute trace of the hydride 

 is sufficient to develop a very considerable odor, and traces of 

 moisture may be enough to produce a perceptible odor of the 

 hydride when the conditions are favorable to action upon the 

 elementary selenium. When selenium burns in air, or when its 

 sulphide is oxidized by aqua regia, moisture is inevitably present, 

 and when selenium dioxide is reduced by sulphur or inter- 

 mixed with elementary selenium its extremely hygroscopic 

 character implies the presence of traces of water. 



It has been a generally accepted opinion of late that the 

 selenium monoxide does not exist, but more recently, in work 

 upon certain organic compounds of selenium, Chabrie has been 

 led to the idea that the monoxide does exist and that it is a solid 

 body. Chabrie statesf that when selenium is heated in air it 

 tends to increase in weight. At 100° C. the increase is said to 

 be inappreciable, but at 180° C. it approaches very nearly to 

 the limit corresponding to the formation of the selenium mo- 

 noxide, SeO. Further he says that this increase in weight when 

 the selenium is heated to 180° cannot be due to the formation 

 of the dioxide, since that compound, if it were formed, could be 

 seen as a crystalline deposit; or if the temperature is too high 

 to allow it to deposit, a loss of weight would result. He is so 

 sure of the increase that, were it not for the fact that the mo- 

 noxide has not been generally recognized, he would suggest as 

 a possible means for the determination of selenium to heat it 

 to 180° and estimate it as SeO. The selenium with which 

 Chabrie obtained these results was reduced by acting with 

 sodium sulphite and hydrochloric acid upon the product of 

 oxidation of certain organic compounds of selenium of the 



* Annales de Chimie et de Physique III, xxi, 119. 

 f Ibid., \l, XX, 273. 



