56 Mr. T. J. Pearsall on the 



solution by an alkali, it will consist of the mixed states in 

 previous solution ; and hence, because a brown or red oxide 

 may be thus obtained, it cannot be admitted as a proof that 

 this is the same state which existed in the solution ; and, on 

 the contrary, the same precipitated oxide when dissolved by 

 acids being resolved into the same states as before, therefore a 

 crimson fluid obtained from a red or brown oxide is, in itself, 

 no proof that the same oxygenated state of manganese is taken 

 into solution which was acted upon by the acid ; so that there 

 seems no satisfactory evidence of either the red, deut, or the 

 peroxide in the crimson solutions of manganese. The con- 

 stant presence of either the red or deut oxides seems irrecon- 

 cilable with the fact, that every degree of oxidizement higher 

 than the protoxide will afford red solutions ; this, however, 

 agrees with the production of manganesic acid. 



It has often been remarked as a singular circumstance, that 

 so small a quantity of the red or deutoxide should be capable 

 of causing deep tints * ; but these observations will accord 

 with the fact, that a minute portion of manganesic acid can 

 produce intense colour. The experimental formation and the 

 theoretical composition of manganesic acid afford arguments 

 in favour of its presence in the ordinary red solutions. Dr. 

 Forchammer f first separated this acid from bases ; the pro- 

 cess which he employed consisted in precipitating a solution of 

 green chamelion by nitrate of lead: he describes the dark 

 brown precipitate as a mixture of peroxide of lead and 

 deutoxide of manganese, which, by digestion with sulphuric 

 acid, formed sulphate of protoxide of lead, while the oxygen 

 given off united to the deutoxide of manganese to form man- 

 ganesic acid ; here there is a mixture of oxides, one of which 

 is resolved into protoxide. Now, if we substitute peroxide of 

 manganese in the place of peroxide of lead, then, by analogy, 

 the action of sulphuric acid is, as before, to resolve peroxide 

 into protoxide, while the oxygen given off unites to the 

 deutoxide to form manganesic acid ; and upon this view the 

 changes may be expressed as follow : each proportional of per- 

 oxide by the action of sulphuric acid loses one proportional 



* Dr. Turner, Phil. Mag., iv. 31 ; and Phillips, Phil. Mag., N, S., v. 216, 

 f 4wal$ of Philosophy, xvi, p. 133. 



