Red Solutions of Manganese. 61 



together to a certain extent by excess of acid, which condition 

 accompanies all the ordinary red solutions of manganese. 



Acid solutions of sulphates of potash, soda, magnesia, and 

 zinc, appear of a clear red colour after mixture with the red 

 sulphuric acid, or with manganesate of potassa. The borates 

 of potassa and soda are also reddened by both solutions; and 

 the red sulphate, or the crimson oxalic fluid from oxides, may 

 have their colour increased by the addition of manganesate of 

 potassa. Thus both sets of solutions are similarly compatible 

 with other fluids. 



When a solution of chloride of lime (bleaching powder) is 

 added to proto-salts of manganese, the protoxide, by the agency 

 of chlorine, receives additional oxygen, and is converted into 

 peroxide. On using the muriate, I observed that, after some 

 days, the supernatant fluid became bright pink ; and, expecting 

 that protoxide of manganese would be absent from this solution, 

 I examined it more particularly. The colour, increasing by 

 time, became pink and violet, like a solution of pure manga- 

 nesic acid, which I found was present, for potassa precipitated 

 lime, and then changed this red fluid to blue and green cha- 

 melion. I have obtained red fluids in this way several times*. 



The solutions of the bleaching chlorides of potassa and soda 

 have frequently pink tints, supposed to be due to the introduc- 

 tion of manganese in some unknown state into the liquor, 

 while chlorine gas was passing through the apparatus. Prac- 

 tically it was found that the fluids could only be obtained 

 colourless by slowly disengaging the gas ; for whenever the 

 chlorine was rapidly evolved, if the solution was caustic potassa 

 or soda, it always became pink or red. 



I procured two specimens the one was colourless, and the 

 other pink ; and I added an aqueous solution of manganesic 

 acid to the colourless fluid, which instantly assumed a similar 

 but much deeper tint than the coloured fluid : then the co- 

 loured fluid had its colour 'greatly increased by manganesic 

 acid ; neither fluid exhibited any other change by such addi- 

 tion. I found that manganesic acid and manganesates were 



* Mr. Phillips, alluding to the same fact, says, that ' the muriate of manganese 

 should be as nearly saturated as possible, for the chlorine evolved by excess of 

 muriatic acid occasions the acidification of a portion of the manganese,' Annalj 

 of Phil., N. 8., v., p. 216. J 



