62 Mr. T. J. Pearsall on the 



compatible with all the bleaching chlorides of caustic and 

 carbonated alkalies : in some experiments the tints were 

 unchanged after four months. 



On the supposition that an oxide is the cause of the well- 

 known tints of manganese, it seems difficult or impossible to 

 account for the introduction of any of the oxides into these 

 fluids ; for neither the prot, red, deut, or peroxide, or any of 

 their compounds, are volatile ; and even if one of them be 

 admitted to be present, it could not be retained in these solu- 

 tions, because they are decidedly alkaline. Now^ on the view 

 which I advance, manganesic acid can exist in solutions of 

 carbonates and bi-carbonates, and in these bleaching solutions. 

 Manganesic acid is volatile, as are the perchloride and the 

 fluoride of manganese, which, on decomposing, form manga- 

 nesic acid*. 



These facts I consider will satisfactorily explain the hitherto 

 almost anomalous appearance of manganese in certain cases 

 of experimental research, and in various processes in the 

 arts f. 



From all that has been advanced, it would appear that 

 bleaching properties, which have sometimes been attributed to 

 chlorine, in certain cases, belong to all red solutions ; and 

 that these solutions are similar to such as contain manganesic 

 acid for both solutions are alike in colour and in bleaching 

 power ; both become colourless by the same agents ; both 

 lose the bleaching power by losing the coloured state ; both 

 afford similar indications by reagents ; both, while red, afford 

 a red salt in crystals, which appears to possess the same pro- 

 perties ; both, when they lose colour, afford a crystallized 



* Quarterly Journal of Science, xxv., p. 486. 



f Manganese was observed in a solution of carbonated alkali, into which it 

 had been carried by chlorine, although the gas had been washed with water, 

 and had also passed through an alkaline solution, before the oxide was deposited 

 in the second bottle of Woulfe's apparatus. Quarterly Journal of Science, vol. 

 xxv., p. 86. 



Chloride of lime is frequently obtained which dissolves with a pink colour due 

 to manganesic acid, although the chlorine gas had been transmitted through 

 water. 



Mixtures of chlorides of lime and potassa, prepared for some manufacturing 

 purposes, constantly afford a deep red solution, and possess extraordinary bleach- 

 ing powers. 



Manganesic acid also colours the solutions in the formation of the salt called 

 chlorate of potassa. 



