170 



Investigation of thh Actlon Between Manganese Dioxide and- 

 Potassium Chlorate in the Production of Oxygen. 



Edward G. Mahix. 



The inethod for i)roi»;irin.u- oxyKfH I'.v lieatiii.t; inixtui-cs of potassium 

 chlorate and iiiaunaiicso dioxide has heeii v.^vtl l>y eh; mists for some time. 

 Since, however, the nian.iianese dioxide comes out unchanged at the end 

 of the process, yrt consideralily lowers the temjierature necessriry for de- 

 coniiiosition of iiotassiiuu chlorate, its exact function has heen and is yet 

 imi;erfectly understood. 



There is not only a iiractical, Init also a very intir;'stin.y theoi'etical 

 ([uestion in\olved in the exiiliiualion of the reaction takinn' place in this 

 process, and it was the desire for obtaining further light on certain 

 points that lid Professor Ransom and the writer, at the suggestion 

 of the former, to jointly- und' rtalce a study of the facts. S:nne questions, 

 the settlement of which was to Ite attempted, were: 1. I)o;'s variation in 

 proportion of potassium chlorate and manganese dioxide affect the t'-m- 

 perature at which oxygen is evolved, and, if so. wli.it mixture yields it at 

 the lowest temperature? "J. Is tlie .action continuous wlit'ii the mixture 

 is heated for a long period at or just alove the decompositiim tempera- 

 ture, and what are the products? 3. Heating for a period just below this 

 temperature, are any intermediate products formed and what are they? 

 4. To notice any new facts brought out by the experimental work. 



Search of the literature shows that the men who have performed the 

 most important work upon this particular phase of the subject are Mc- 

 Leod. Brimck and Scnleau. McLeod had noticed the well-known fact that 

 a gas resembling chlorine was evolved with oxygen, and in ISSO, pub- 

 lished a statement of experimental work, dedm-ing the following reactions: 



2 Mu O2 + 2 K CI O3 = K2 Mn2 Os + CI2 -j- O2. 

 K2 Mu2 Os = K2 Mil O4 + Mil O2 + O2. 

 K2 Mn O4 + Cl2 = 2 KCl 4 Mil O2 f O2. 



rpon this basis he explained the supi>osed fact that free chlorine is 

 evolved only at the beginning of the process, since chlorine is liberated l)y 

 the first reaction and at the lowest temperature, and that corresponding to 

 this free chlorine, there was a certain amount of undecomposed potassium 

 manganate at the end. In ISO?, Brunck argued that if these reactions 



