1820.] Manganeseous and Mmiganesic Acids. 135 



water containing the powder of peroxide of manganese. My 

 object was to see whether I could produce a degree of oxida- 

 tion higher than the peroxide. When I added potash to the 

 water thus saturated with chlorine, I got a small quantity of 

 deutoxide of the manganese, probably because a small quantity 

 of deutoxide had existed in the peroxide, and the fluid over this 

 powder soon became red. There exists some submagnesiates 

 which are insoluble, and form a red powder, but I never could 

 find out any method of producing them in a direct way. They 

 are merely obtained by accident ; and I have principally noticed 

 that of barytes. All the oxides of metals seem either to form 

 soluble compounds ofared colour with the manganesic acid, or to 

 decompose it, in which case the oxide of the metal is converted 

 into peroxide, and the manganesic acid reduced to deutoxide. 

 This I found to be the case with lead, and it seems to hold also 

 with silver. The brown powder thus obtained by lead is soluble 

 in cold nitric acid with a brown colour ; when heated, it turns 

 red. This fact proves that it is a real chemical compound of the 

 brown peroxide of lead (acting as an acid), and the deutoxide of 

 manganese, for neither the first nor the second of these bodies is of 

 itself soluble in nitric acid. By the elevation of the temperature 

 to that of boiling water, the oxygen from the peroxide of lead 

 goes over to the manganese, and changes it into acid. I first 

 believed that under certain circumstances the nitric acid might 

 be able to reduce this compound to protoxide of the two metals ; 

 without that supposition I could not make out what had become 

 of the oxygen; but afterwards I found itprobable that it depended 

 upon a small quantity of nitrous acid combined with the nitric 

 acid. 



The manganesite of baiytes I obtained by igniting nitrate of 

 barytes together with oxide of manganese, and washing the 

 green powder thus obtained with boiling water. It has a beau- 

 tiful emerald green colour, and, when dry, is very little altered 

 by the air. Manganesite of lime I could not obtain in the same 

 way. 



In order to ascertain the quantity of oxygen in the manganesic 

 acid, I precipitated a solution of the green chamaeleon which was 

 very clear, by nitrate of lead. The brown powder was dried, 

 and I put it with bisulphate of potash into a retort, which, by 

 means of a tube of glass, was connected with a glass vessel, 

 open below, and shut above, by means of a stop-cock. I filled 

 the vessel with water before I put the apparatus together, and 

 then opened the cock to see whether it was quite tight. 

 When after some hours no change had happened, I heated 

 the retort so as to melt the bisulphate of potash, and kept it 

 warm until the brown powder had lost its colour entirely, and 

 was converted into sulphate of lead and sulphate of manganese. 

 The glass vessel contained a volume of air equal to the volume 

 of oxygen expelled from the brown compound, and it might con- 



