1820.] Manganeseous atid Manganesic Acids. 131 



entirely ; and Chevillot and Edwards have proved by an inge- 

 nious experiment that even the peroxide of manganese and 

 potash, when heated together, absorb oxygen, in order to form 

 the green compound. It is well known, that their experiments 

 induced them to consider the red compound of oxide of manga- 

 nese and potash as a neutral manganesiate of potash, and the 

 green compound as a submanganesiate of potash ; but they were 

 unable to procure the manganesic acid in a separate state. 



I happened about the same time to be engaged in an inquiry 

 into the nature of the different oxides of manganese, and was 

 fortunate enough, though unacquainted with the late papers of 

 these French chemists, to procure the same acid quite in another 

 way, and even to hit upon a method of obtaining it in a separate 

 state. 



I prepared a solution of green chamaeleon by igniting potash 

 with peroxide of manganese, and dissolving the green salt in 

 water. After the solution, there remained deutoxide of manga- 

 nese ; the peroxide being decomposed by the action of potash, 

 and a portion of its oxygen accumulated in that part of the 

 peroxide which was dissolved. The green solution very soon 

 became red, but at the same time it deposited deutoxide of 

 manganese with a brown colour. 



When I added to the red solution of chamaeleon a solution of 

 very pure potash, it did not change the colour at all ; but when 

 I afterwards added the least drop of alcohol, the colour began 

 immediately to assume a tint of green, and if there was alcohol 

 enough, the most beautiful green was produced. When too 

 much of alcohol was added, all the colour disappeared, and 

 deutoxide of manganese was produced. 



These experiments rendered it probable that the difference 

 between the green and the red chamaeleon consisted not in the 

 quantity of potash combined with the oxide of manganese, but 

 in the different quantity of oxygen combined with the manga- 

 nese ; for it is certain that the oxide of manganese combined 

 with potash in the green chamseleon contains more oxygen than 

 the deutoxide. Indeed as it contains even more oxygen than 

 the peroxide, and as part of the oxide of manganese in the green 

 solution is reduced to deutoxide, it is necessary to suppose 

 either that the oxygen is accumulated in the other part, or that 

 it is combined with the potash or water, which certainly is not 

 very probable. I took another portion of the red solution and 

 poured into it a solution of potash containing the powder of car- 

 bonate of manganese. 



As soon as it was added, the colour changed directly into a 

 more or less beautiful green, and the protoxide of manganese 

 was directly converted into deutoxide. If I added too much of the 

 liquor, the whole was changed into deutoxide. This experiment 

 proves quite clearly that the green solution contains less oxygen 

 than the red solution of the chamasleon. However the oxide in 



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