143 



more rapid. To get some idea of the pai't the metal might be phiying a 

 strip of ph^tinum foil about a foot long was thoroughly cleaned and put 

 into a glass tube. A dilute solution of permanganate was poured in to 

 cover the metal, and the tube stop])ered. Gradually a brown deposit ap- 

 peared on the platinum and floating in the liiiuid. In twelve days the color 

 was discharged. Treateil with hydrochloric acid the brown solid gave tlie 

 odor of chlorine. Tlie same result was obtained when hydrogen was passed 

 into a solution of permanganate containing granulated zinc. The colorless 

 filtrate from the zinc was strongly alkaline, contained potassium, but only 

 a trace of manganese. 



In order to study this action more in detail some granulated zinc was 

 allowed to stand in contact with a solution of the permanganate. Grad- 

 ually reduction occurred the zinc becoming covered with a gold-yellow de- 

 posit. The reduction became slower as the deposit on the zinc increased. 

 Finally the solution became colorless and gave an alkaline reaction. 



In a roughly quantitative experiment two grams of permanganate were 

 dissolved in especially purified water and this solution placed with a large 

 quantity of zinc. The mixture was shaken periodically. In a month the 

 liquid had become colorless. The liquid was filtered from the zinc and the 

 latter thoroughly washed. Titration of this li(iuid with methyl orange, 

 against a standard acid, gave 89 per cent, of the theory for the hydrolysis 

 of the permanganate. As much as possible of the yellow solid was re- 

 moved from the zinc and this with the finer particles was treated with 

 nitric acid to dissolve any zinc. On treatment the solid darkened. ts 

 weight was .9077 grams, and it gave chlorine with hydrochloric acid. 



In order to understand what was the reducing agent in the above 

 reaction a quantity of \xe\l cleaned zinc was placed in a flask with especial- 

 ly purified water. The flask was connected with a eudiometer filled with 

 the same kind of water. The eudiometer \Aas arranged so that the water 

 might be displaced by a gas. Gradually hydrogen was formed. By stir- 

 ring the zinc about the hydrogen passed into the eudiometer. In .S5 days 

 twenty-five cubic centimeters of hydrogen liad collected. This burned 

 quietly sliowing no admixture with oxygen. The experiment was then 

 discontinued. 



The results of the experiments with ]>ermanganate indicate that its 

 solution is hydrolized and that the free acid is then reduced eitlier directly 

 by the zinc or l>y the nascent! hydrogen prodnced by the action of zinc on 



