590 MR. H. BRERETON BAKER ON COMBUSTION IN DRIED OXYGK.N 



Combustion of Boron in Oxygen. 



In these experiments the boron used was given to me by Mr. FRANCIS JONES, of 

 Manchester. It had been prepared by him in his researches on boron hydride. As 

 hydrogen might be occluded in the substance, it was heated in a tube of hard glass 

 connected with a Sprengel pump About twelve times its volume of gas was evolved, 

 which burnt in air with a green flame. It was probably boron hydride. The boron 

 was then sealed in a tube with oxygen, and left drying for a week. It burnt readily 

 on heating. As all the hydrogen might not have been removed, it was placed in a 

 tube, and heated for three days in an air bath at 200 in boron chloride vapour. A 

 large quantity of hydrochloric acid was produced, and it was only after treating it in 

 this manner three times that the boron chloride did not evolve hydrochloric acid gas. 

 After the hydrogen had thus been eliminated, the boron was heated in dried oxygen, 

 and found not to undergo combustion at the bright red heat of the blow-pipe flame. 

 The end of the glass tube in this experiment was bent and made to dip under mercury, 

 to prevent the glass from blowing out under the pressure of the heated oxygen. 



Combustion of Arsenic in Oxygen. 



Commercial arsenic was mixed with purified charcoal and heated in a vacuous glass 

 tube. The crystalline sublimate was heated in a sealed tube with arsenic chloride 

 vapour. The arsenic was then distilled again in a vacuous tube, at one end of which 

 was a piece of solid potash to absorb hydrochloric acid. 



Two experiments were made with this substance. In the first the oxygen was 

 dried over phosphorus pentoxide for one, in the second for two months. The arsenic 

 was found to burn as readily when dry as when moist, and when the ends of the 

 tubes in which the experiments were done were broken under mercury, the mercury 

 filled them entirely, showing that the oxygen was used up in both cases. 



Arsenic, therefore, when purified in this way burns in dry oxygen. 



Combustion of Antimony in Oxygen. 



This element was prepared by heating tartar-emetic with charcoal. The metal so 

 obtained was powdered, and placed in a hard glass tube, which was then filled with 

 chlorine. The tube was then heated to 200 in an air bath. The process was 

 repeated twice. The antimony so obtained was freed from hydrochloric acid by 

 heating in vacuo over potash. On being heated in oxygen which had been dried for 

 six weeks, it was found to burn readily. Two other experiments were done, in one of 

 which the antimony was heated in oxygen which had been dried over phosphorus 

 pentoxide for four months but neither showed any difference in behaviour between 

 the moist and dry gas. 



