216 Mr. Phillips 07i a riew Oxide of Manganese.- Sfc. 



small quantity mentioned above, the proportion of deutoxide 

 held in solution was to that decomposed, only about as 1 to 

 10. It is very remarkable, as Dr. Turner has observed, how 

 small a quantity of oxide gives colour to a large quantity of 

 solution; thus from what I have stated, it is evident that 

 about 6 grains of deutoxide impart a colour equal in intensity 

 to that of port wine, to a pint of solution of sulphate of man- 

 ganese. The red sulphate is also very easily procured by 

 moderately heating the artificial deutoxide in sulphuric acid. 

 It has been already noticed that the deutoxide of manganese 

 is obtained by merely drying the protoxide precipitated by 

 potash ; the peroxide is also easily procured by decomposing 

 the muriate of manganese with chloride of lime ; the precipi- 

 tate is so extremely bulky, that a vial holding 1000 grains of 

 water, contained, even when well shaken down, only 60 grains 

 of it. In employing chloride of lime, the solution of muriate 

 of manganese should be as nearly saturated as possible; for 

 the chlorine evolved by excess of muriatic acid, occasions the 

 acidification of a portion of the manganese. I have some 

 reason to suppose that the peroxide thus obtained is a hy- 

 drate, containing a very small atomic quantity of water. 



With respect to the red oxide of manganese, I would ob- 

 serve that, of all the oxides, it is the only one which suffers no 

 change by the action of heat; the protoxide by absorbing 

 oxygen being converted into it, while all other oxides, by 

 evolving the same element, undergo a similar change : on this 

 account it forms a very convenient standard in analysis ; it is 

 obtained of the reddest tint, and with least admixture of 

 purple, by using an artificial peroxide. 



In concluding, I will state what appears to be the composi- 

 tion of the oxides and acids of manganese at present known ; 

 premising, however, that I have made no experiments upon 



the two acids. 



Atoms. 

 M. o. M. o. 



Protoxide 1 + 1 28+8 



Deutoxide 2 + 3 28 + 12 



Peroxide J +2 28 + 16 



Red oxide 3 + 4 28 + 10-66 



Warwick oxide ... 4 + 7 28 + 14 



Manganous acid . . 1 + 3 28 + 24 



Manganesic acid . . 1+4 28 + 32 



XXXIII. Ecplj^ 



