Red Solutions of Manganese. 63 



colourless proto-salt ; both are compatible with certain other 

 solutions of other substances. From these close and numerous 

 points of comparison, I conclude that the effects of all red 

 solutions of manganese depend upon manganesic acid. 



The production of manganesic acid in the cases investigated 

 is agreeable to theory ; and if its presence be considered as 

 established, some important consequences follow. The soluble 

 states of manganese are thus resolved into colourless protoxide 

 and manganesic acid. When oxygen is liberated from per- 

 oxide by sulphuric acid, manganesic acid may be alternately 

 produced and destroyed. The composition of any oxide which 

 has been or may be obtained from a red solution will obviously 

 depend upon the quantities of protoxide and manganesic acid ; 

 and this explains the variable proportions which have been 

 obtained with such precipitates. 



The view I have taken may have many interesting bearings. 

 Thus the red oxide is composed of 28 metal and 10.66 oxy- 

 gen, and the deutoxide of 28 metal and 12 oxygen; and 

 these are assumed to form with acids very feeble indefinite 

 compounds, existing only in the cases referred to, and not 

 volatile. On the contrary, manganesic acid, the cause now 

 assigned of the redness of the solutions, is constituted of 28 

 metal and 32 oxygen : it is capable of existing in the solid or 

 anhydrous form, or in the state of vapour, and so be trans- 

 ferred from one situation to another. It is soluble in water, 

 in certain alkaline fluids, in some acids, and in solutions of 

 many saline compounds. It is capable of combining with 

 alkalies and earths ; when decomposing, it can impart oxygen 

 to other bodies, and thus produce or modify effects which may 

 have been referred to other causes, when its presence has not 

 been suspected. 



I have given the evidence as much as possible dependent 

 upon the qualities of the solutions, and purposely so, in order 

 that the view now brought forward may not be interfered with, 

 should the proportions of any of the compounds be subject to 

 correction. Having drawn my conclusions from experiments, 

 I have adverted to the opposing statements of authorities only, 

 to show the opinions entertained upon this subject of acknow 

 Jedged difficulty. 



