Manganic and Hyper manganic Acids, Sfc. 181 



1*204 gr. of manganate of potash, decomposed by muriatic 

 acid and precipitated by carbonate of ammonia, yielded 

 0*459 gr. ignited red oxide of manganese ; and the liquid 

 evaporated to dryness and heated to redness, gave 0*882 

 chloride of potassium ; or 100 grains would have given 

 46*34 potash, and 38*12 red oxide of manganese. These 

 38*12 parts of red oxide are equivalent to 44*30 of the 

 binoxide, containing 15*95 of oxygen. Therefore, the 

 oxygen extricated by the action of the nitric acid, is nearly 

 half that contained in the residual manganese. Now, 46*34 

 potash contain 7*85 oxygen, that is half that of the binoxide 

 of manganese, or ^ of that in the manganic acid. If we 

 calculate from this the composition of the manganate of 

 potash, we find it to be composed in 100 parts of 47*37 

 potash, 52*63 manganic acid. 



When 52*63 parts of manganic acid are converted into 

 binoxide of manganese, 8*03 parts of oxygen ought to 

 be extricated ; the increase of {q in the result of the experi- 

 ment is occasioned by the extreme facility with which the 

 salt is decomposed, by which the potash is diminished in 

 quantity. 



The hydrated binoxide of manganese has already been 

 discovered by Berthier, and prepared by various methods, 

 but it was not known that it could be prepared by the 

 decomposition of manganic and hypermanganic acids. 

 When prepared from these acids by nitric acid, its colour 

 is so deep brown as to appear almost black, but when 

 prepared by sulphuric acid it is somewhat lighter. An 

 unknown quantity of this oxide was ignited in a retort and 

 the oxygen extricated was collected ; this (the barometer 

 standing at 30 inches and the thermometer at 32°) measured 

 46*2 C. C, or 0*06618 grammes. I could not succeed in 

 converting it into red oxide in the retort, but when heated 

 strongly in a platinum crucible, it gave out 0*049 gr. of 

 oxygen, and became red. The red oxide obtained, weighed 

 0*954 gr. To be more certain of its amount, it was treated 

 with sulphuric acid, and the solution evaporated to dryness 

 and ignited. The sulphate of manganese weighed 1*8363 

 gr., corresponding to 0*9521 gr. red oxide. 0*954 gr. red 

 oxide of manganese are obtained by igniting 1*083 gr; 

 binoxide, as they contain 0* 129 gr. oxygen. According to the 

 experiment, the loss in the quantity employed was 0*115 gr. 



