Analysis of Iron Ore. 35 



were perfectly colourless : after having concentrated them, I 

 precipitated from them, by carbonate of soda, a white flaky 

 matter, very light, which, at first sight, I took for the oxide 

 of manganese. 



It having appeared, upon pouring a little caustic soda into 

 the liquors, that in spite of the excess of alkali a portion of 

 white matter remained in solution, I boiled them in order 

 to drive off the carbonic acid, which it is believed has the 

 property of dissolving several earthy and metallic substances. 

 I filtered them afterwards in order to collect the precipitates: 

 after having cleaned them well, I separated them from the 

 filter, and calcined them for fifteen minutes in a crucible of 

 platina: No. I. weighed 0-25 grammes; No. II. 0*70; 

 No. III. 0-68. 



(D) The gelatinous appearance of these precipitates sur- 

 prised me so much the more, as I did not know this property 

 in the carbonate of manganese : I was still more astonished 

 when I took them out of the crucible as white after calcination 

 as they were before; because the carbonate of manganese loses 

 its acid and becomes black at a degree of heat even inferior to 

 that which I had used, while the matter of which we are 

 now speaking had retained a good deal of carbonic acid and 

 preserved all its whiteness. A second calcination did not 

 produce any remarkable change. This substance melted 

 by the blowpipe with glass of borax, dissolved with effer- 

 vescence without being coloured : nitrate of potash thrown 

 upon the burning mass did not produce the violet colour 

 which characterizes the oxide of manganese, notwithstand- 

 ing 1 made use of a supporter of baked clay in place of char- 

 coal, in order to remove every thing which could obstruct 

 the colour. The precipitates obtained from the salts of man- 

 ganese by the caustic alkalis speedily become brown in the 

 air; the above substance presented no such appearance: 

 dissolved in the sulphuric and nitric acids, it was nenher 

 precipitated by the hydro-sulphuiels nor by the alkaline 

 prussiatcs: the latter scarcely give it a blueish casi. By 

 means of the oxalate of ammonia a slight precipitate is ob- 

 tained, which is slowly formed, and which is rcdissolved 

 in water or in an excess of acid. 1 ought to observe lure, 

 C 2 that 



