170 Dr TURNER'S Chemical Examination 



The quantity of water was determined as usual by means of 

 the chloride of calcium, and amounted to T12 per cent. 



On exposing 23746 grains of this oxide to a white heat, the 

 loss proved to be 3'064 grains or 12'90 per cent. Subtracting 

 1*12 for water, there remain 1178 as the loss of oxygen. 



Accordingly, 100 parts of the Pyrolusite were resolved into 



Red oxide ..... 84*055 

 ^Oxygen ...... Ill '78 



Baryta . . '. . . . uO'532 

 Silica 0-513 



100-000 



Now, omitting the water, baryta, and silica as accidental impu- 

 rities, the remaining 97'835 parts lose 1178 parts, or 12*04 per 

 cent of oxygen in being converted into the red oxide. On the 

 supposition that Pyrolusite is composed of one equivalent of 

 manganese and two equivalents of oxygen, it should lose in pass- 

 ing into the state of red oxide exactly 12-122 per cent of oxygen, 

 a quantity which corresponds closely with the result of analysis. 

 It is therefore an anhydrous peroxide of manganese. 



I have analysed another columnar variety of Pyrolusite, which 

 has a density of 4-819, and of which the individuals radiate from 

 a common centre. I brought it with me from Germany, and be- 

 lieved it to be from Ihlefeld, as the ticket indicated ; but Mr 

 HAIDINGER, after carefully inspecting several large cabinets in 

 Germany, has been unable to discover any similar specimen which 

 is known to have been found in that place. Its locality there- 

 fore is doubtful. 



This variety is less pure than the foregoing. Before being 

 washed, it yields chlorine on the addition of sulphuric acid ; and 



