578 



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



tube any carbon monoxide which was produced in the combustion would be converted 

 into carbon dioxide. Next in the series was a third set of potash bulbs to absorb this 

 carbon dioxide. The calcium chloride tube of this third set of bulbs had a conducting 

 tube attached to it which dipped under mercury contained in a trough. Here the 

 residual gas was collected. 



The carbon was raised to a red heat by a Bunsen burner. No visible combustion 

 took place. Oxygen was passed over it at the rate of about 20 bubbles a minute. 

 The gas collected over the mercury was at first a mixture of oxygen and nitrogen. 

 The latter was derived from the air contained, at the beginning of the experiment, in 

 the bulbs and the copper oxide tube. The gas collected towards the end of the 

 experiment was pure oxygen. 



When all the oxygen had been driven over the charcoal, the potash bulbs were 

 disconnected, filled with air, and weighed. The second set, which were used to test 

 the efficacy of the first set, had not increased in weight. From the increase in weight 

 of the first set, the weight of carbon dioxide produced in the combustion was found. 

 The increase in weight of the third set gave the weight of carbon dioxide produced 

 by the oxidation of the carbon monoxide formed in the combustion. The analysis of 

 the gases so found yields the following results : 



Carbon dioxide .... 1*7 

 Carbon monoxide . . . 27'8 

 Oxygen (by difference) . 70 '5 



lOO'O 



These striking results are confirmed by the analyses of the gases contained in sealed 

 tubes after charcoal had been heated in dried oxygen, mixed with nitrogen. 



That this carbon monoxide was not produced by the reduction of carbon dioxide by 

 charcoal was shown by a series of three experiments, described later. 



It was thought that, if a rapid current of air were passed over charcoal heated to a 

 temperature below the ignition point* of carbon monoxide, the carbon monoxide, if 

 produced, might be swept away from the area of combustion before it was oxidized. 



The air used in the experiment was freed from water vapour by passing through 



* MM. MALLARD and LE CHATELIER found that a mixture of carbon monoxide and oxygen ignited at 

 abont 650 C., though gradual union took place at 400. (' Annales dcs Mines,' vol. 4, 1883.) 



