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



In every case, irrespective of the reducing agent employed 

 or details of treatment, I get a loss of weight on heating 

 selenium in air to 180°, due to the volatilization of the 

 selenium. If this is so, it should be possible to so arrange the 

 apparatus that the selenium volatilized may be caught and 

 weighed. 



A drying tube with ground-in stopper was, therefore, sealed 

 to a smaller tube carrying a bulb filled with ignited asbestos. 

 The selenium was weighed and introduced upon an asbestos 

 felt into the larger tube and the whole was carefully weighed,. 



The larger tube was heated in the air bath, while air was 

 drawn through the tube in the direction of the bulb of asbestos, 

 which was outside the bath and cool. Selenium volatilized as 

 before, very evidently, as far as the asbestos in the bulb, where 

 it was caught. On cooling and weighing the tube and contents, 

 absolutely no change of weight was observed. This shows that 

 no gaseous product is formed to occasion the loss, but that the 

 decrease of weight in the former experiments was due to the 

 volatilization of the selenium itself. 



Thus I am unable to duplicate the results of Chabrie in this 

 matter, although I have followed his method of treatment so 

 far as it is described. The only difference apparent is in the 

 source of the selenium — in this work the dioxide of known 

 purity with which much exact work has recently been done, 

 and in Chabrie's work the oxidation product of certain organic 

 compounds. I fail to see, however, how this difference in 

 origin can affect the sensitiveness of the selenium with refer- 

 ence to the oxidizing action of the air. 



Having thus been unable to obtain the monoxide in the 

 solid state, I have made some experiments upon the oxidation 

 of selenium by heating it in mixture with dioxide and under 

 such conditions that the existence of a gaseous product, such as 

 Berzelius describes it to be, would be noted, even if it were 

 formed in very small amount. 



A hard glass tube of convenient size, about 2'^'^ in diameter 

 and 65^"" in length, was washed and dried most carefully and 

 sealed at one end. Through the open end were introduced 0*0247 

 grm. pure selenium dioxide, freshly prepared and scrupulously 

 protected against moisture, and 0-0250 grm. powdered selenium. 

 The open end was then drawn out in such a way that attach- 

 ment could easily be made to an air pump and an intervening 

 portion of the tube constricted so as to be easily sealed later. 

 The end was attached to a mercury air pump and the pressure 

 reduced to 4"""". By applying a flame to the constricted part 

 the tube was sealed in that condition. The tube was heated 

 gradually in a small combustion furnace until the whole con- 

 tents were vaporized, maintained in that condition some 



