580 MR. H. BRERETON BAKER ON COMBUSTION IN DRIED OXYGEN. 



Experiment IV. The carbon was placed in a U-tube, which was heated in the 

 vapour of boiling sulphur (440). 



Carbon dioxide 57'28 



Carbon monoxide 4272 



100-00 

 Experiment V. Temperature of carbon 440. 



Carbon dioxide 60 '8 G 



Carbon monoxide 39 '14 



100-00 



Experiment VI. At 440. 



Carbon dioxide 46'8 1 



Carbon monoxide 53" 19 



100-00 



In the sixth experiment the rate of passage of the gas was increased to 40 

 bubbles a minute. 



Experiment VII. Instead of air a mixture of oxygen and nitrogen containing 

 15'4 per cent, of oxygen was used. It was contained in a large bell-jar dipping in a 

 large and deep pneumatic trough (fig. 4). Temperature of the carbon 440. 



Percentage of carbon dioxide = 33*4 

 ,, carbon monoxide = 66 "5 



99-9 



Thus carbon monoxide is always produced when carbon is heated in such mixtures of 

 oxygen and nitrogen at temperatures below 500. It might, however, be due to the 

 reaction 



CO 2 + C = 2CO 

 instead of 



2C + O 2 = 2CO. 



This supposition was proved to be untenable by the following experiments : 

 Experiment I. Pure carbon dioxide was passed very slowly over carbon heated to 



the melting-point of lead chloride (500). The gas was then collected over mercury 



in a gas pipette. 278 c.c. of gas was collected in three hours, so that about 1'5 c.c. 



of gas passed over the charcoal in a minute, This collected gas was entirely absorbed 



by caustic potash. 



Experiment II. At the same temperature 150 c.c. of carbon dioxide was passed 



over the heated charcoal at the rate of 1 c.c. a minute. It was entirely absorbed by 



caustic potash. 



