M, JE, Mitscherlich on Manganic Acid, Sfc, 331 



Article III. 

 On Manganic and Hypermanganic Acids, on Hyperchloric 

 Acid and the Salts of these Acids. By E. Mitscherlich. 



{Concluded from page 183.) 



If hy permanganate of potash be dissolved in a solution of 

 potash, and the solution evaporated under the air pump 

 over sulphuric acid, the red crystals of hypermanganate 

 of potash again make their appearance, only a very small 

 quantity being decomposed. 



A very dilute solution of hypermanganate of potash is 

 converted by caustic potash, in the cold gradually, but 

 when heated more quickly into manganate of potash.* The 

 solution must, however, be so dilute, that the liquid is 

 sufficient to absorb the oxygen which is extricated. If the 

 decomposition happens slowly, the quantity of the green 

 increases gradually, the red at the same time diminishing 

 till at last the liquid becomes quite green, and, during the 

 change, a succession of colours is observed, produced by the 

 mixture of the green and red in different proportions. From 

 these alterations of colour this solution has been called 

 chameleon mineral. If an acid be added to the green solu- 

 tion it becomes again red, binoxide of manganese at the 

 same time being formed, and precipitated in the form of a 

 brown powder. 



One grain hypermanganate of potash, treated with nitric 

 acid, and heated till the acid was completely decomposed, 

 gave out 105*9 C.C. dry oxygen gas, or 0*1518 gr. oxygen. 

 The filtered hydrated binoxide when ignited was converted 

 into 0*4785 gr. of red oxide, which consists of 0*348 gr. 

 manganese, and 0*1305 gr. oxygen. 0*348 gr, of man- 

 ganese acquire 0*196 gr. oxygen to be converted into 

 binoxide. Now, 0*196 : 0*1518 :: 4 : 3*1. Hence, hyper- 

 manganic acid contains 7 atoms oxygen and 2 manganese. 

 According to another experiment, 0*5 gr. hypermanganate 

 of potash yielded 52*5 C. C. oxygen gas. In a third, 2 grs. 

 of the salt gave 0*985 gr. of red oxide, which corresponds 

 with 1*42 gr. of hypermanganic acid, and 1*295 gr. nitrate 



* According to HopfF (Central. &fa«, September, 1836), carbonate of manganese 

 answers better for the preparation of manganate of pota^ than the binoxide. — 

 Edit. 



