2 Mr. H. B. Baker. Combustion in dried Oxygen. [Nov. 1 5, 



free the purified elements from all traces of the agents used in their 

 purification. In this way the elements carbon, sulphur, boron, and 

 phosphorus, the latter in. both red and yellow modifications were 

 found to have their combustion influenced by the dryness of the 

 oxygen. Some chemical union was found to take place, the extent 

 of which varied with the dryness of the substances. In no case, 

 however, did it manifest itself by flame. Ordinary phosphorus was 

 obtained so pure as not to glow in the oxygen dried by phosphorus 

 pentoxide, though the pressure was increased and diminished in every 

 possible way. If water was added rapid combustion at once set in. 



The elements selenium, tellurium, arsenic, and antimony were 

 purified with as much care as was expended on the elements men- 

 tioned above. Their combustion was, however, not found to be 

 affected in any way lay the dryness of the gas. 



In the course of the investigation two facts were discovered about 

 the combustion : (i) of amorphous phosphorus, and (ii) of charcoal 

 in oxygen. Amorphous phosphorus is generally regarded as being 

 incapable of true combustion. It is asserted that before amorphous 

 phosphorus can be heated to its kindling point, it changes into 

 ordinary phosphorus, which then burns. This has been proved not 

 to be the case. Amorphous phosphorus was heated in a current of 

 nitrogen, free from traces of oxygen, to 260, 278, and 300, in three 

 experiments, without undergoing any change to the ordinary modifi- 

 cation. If moist oxygen was substituted for the nitrogen combustion 

 took place at 260. It seems, therefore, probable that amorphous 

 phosphorus undergoes a true combustion in oxygen without previous 

 change to the ordinary modification. 



With regard to the combustion of carbon, it has always been a 

 doubtful question which of the two oxides is first formed. Is carbon 

 monoxide the first product, undergoing further oxidation to the 

 dioxide, or is carbon dioxide the first and only substance formed ? 

 The problem seems incapable of direct solution. It is, however, 

 open to indirect attack. When carbon is heated in a current of 

 oxygen dried for a short time by phosphorus pentoxide, a slow com- 

 bustion goes on, and, though the oxygen is in excess, both oxides are 

 produced. The amount of monoxide, however, is twenty times the 

 amount of the dioxide. Experiments also show that this occurs at 

 temperatures at which dry carbon dioxide is not reduced by carbon. 

 The carbon monoxide must, therefore, be produced by the direct 

 union of its elements, its further oxidation being prevented by the 

 dryness of the gases. Confirmatory experiments were performed in 

 which carbon monoxide was found to be produced by the slow com- 

 bustion of carbon in air at 440, a temperature too low for the reduc- 

 tion of the dioxide by. carbon. It is probable that the ordinary 

 combustion of carbon goes on in two stages, that carbon monoxide is 



