162 Dr TURNER'S Chemical Examination 



quired an amethyst-red tint, a minute quantity of oxygen gas 

 being at the same time disengaged. The nature of the change 

 which is produced when sulphuric acid is heated with the per- 

 oxide of manganese, has already been discussed. 



Muriatic acid, as is well known, acts upon the peroxide of 

 manganese at common temperatures, chlorine gas being disen- 

 gaged with effervescence. If heat and an excess of acid be 

 employed, a colourless muriate of the protoxide is procured ; 

 but in the cold, or if the oxide be in excess, in addition to the 

 protomuriate, a deep red coloured solution is formed, similar to 

 that already mentioned in the description of the red oxide. 



PART II. 



ON THE COMPOSITION OF THE ORES OF MANGANESE DESCRIBED 



BY MR HAIDINGER. 



Method of Analysis. 



PURE fragments of the ores were carefully selected, reduced 

 to fine powder in a mortar of agate, and washed with distilled 

 water. Some of the ores yielded nothing to the action of water ; 

 but from some of them, especially from those of Ihlefeld, minute 

 quantities of the muriate and sulphate of lime, and sometimes of 

 soda, were separated by the action of water. It is the accidental 

 presence of the muriates which gives rise to the disengagement 

 of chlorine when sulphuric acid is added to some of the native 

 oxides of manganese, and which induced Mr MACMULLIN to re- 

 gard chloric acid as a constituent of these ores. For the cor- 

 rection of this error we are indebted to Mr RICHARD PHILLIPS,* 



* Philosophical Magazine and Annals, vol. i. p. 313. 



