EVOLUTION OF OASKS 1 KOM HOMOGENEOUS LIQUIDS. 



271 



HATE of Evolution of Oxygen. 



From these results it is evident that the evolution of oxygen from the chlorate 

 with which the barium sulphate is mixed not only commenced at a lower temperature, 

 but also was more rapid throughout, though the difference between the two rates of 

 evolution diminishes as the reaction proceeds, owing to a greater loss of mass in the 

 one case than in the other. The whole course of the phenomenon is precisely 

 analogous to that observed in the case of the decomposition of sodium formate by 

 strong sulphuric acid in the presence or absence of glass dust. 



In order to determine whether such a chemically inert substance as barium sulphate 

 is as effective a material as ntanganese peroxide in promoting the evolution of oxygen 

 at a temperature below the point of fusion of the chlorate, two portions of 20 grams 

 of the salt were taken. To the one was added '2 gram of barium sulphate ; to 

 the other, '2 gram of manganese peroxide, Mn 6 u , H 8 0, prepared for a previous 

 investigation, and shown by spectroscopic analysis to be free from any considerable 

 quantities of the oxides of the alkalies and alkaline earths. Each of these mixtures 

 was placed in a piece of combustion tubing, the end of which was drawn out into a 

 capillary. The two tubes were heated side by side in an air bath. 



