60 Mr. T. J. Pearsall on the 



potassa, soda, or ammonia, threw down brown oxide in 

 them all. 



Hydriodate of potassa produces no change in solutions of 

 proto-salts, but it destroys the colour of manganesates, pro- 

 ducing an amber tint of free iodine. The oxalic red fluid is 

 similarly affected, and is identical in colour with the red man- 

 ganesates, if oxalic acid be added to them. 



Both manganesic acid and the manganesates mixed with 

 oxalic acid give a bright yellow-green precipitate with prussiate 

 of potassa ; a similar precipitate may also be obtained in the 

 ordinary oxalic crimson solutions. 



By alcohol, the solutions of manganesates and binoxalates 

 afford red crystals. The crimson fluid supposed to hold deut- 

 oxide also throws down red crystals, which appear to have 

 precisely the same properties. 



Thus, three solutions containing manganesic acid, and a 

 red solution supposed to contain deutoxide, have similar pro- 

 perties. 



I have not succeeded in forming red solutions by acting 

 with muriatic acid upon oxides of manganese. Diluted muri- 

 atic acid and green manganesate of baryta gave a crimson 

 solution, which, when added to concentrated and neutral 

 muriate of manganese, threw down brown oxide ; but a crim- 

 son transparent fluid resulted when the muriate had excess of 

 acid. Muriatic acid changes green chamelion red, and muriate 

 of manganese may then be mixed with it*. Nitric acid and 

 oxides do not form a red solution, but strong manganesic acid 

 communicates pinkness to the solutions of proto-nitrate of 

 manganese. All these solutions very soon become scarlet and 

 turbid: however, these experiments show that manganesic 

 acid, protoxide of manganese, potassa, or baryta, may exist 



* H. Rose (Treatise on Chem. Analysis, pp. 91, 92) describes the properties of 

 a dark brown solution of deutoxide of manganese in muriatic acid ; and says that, 

 ' by boiling, the perchloride is rapidly reduced to protochloride.' It is also stated 

 that ' the peroxide of manganese dissolves in the cold acid, and also produces a 

 dark brown solution of deutoxide of manganese.' It may be sufficient for me to 

 observe, that, as these are not red solutions, they need not be considered as opposed 

 to the view which I am supporting ; and even if they should hereafter be proved 

 to contain dissolved deutoxide, then it is obvious that this oxide will give a dark 

 brown, and not a pink or crimson solution. Finally, the perchloride of manganese, 

 when decomposed, forms muriatic and manganesic acids, according to M. Dumas, 

 who discovered this compound. Edin. Journ, Science, xv., p. 179. 



