

ON MANGANESE 81 



manganese is very loosely combined with the alkali ; for it 

 can be separated from it by water alone. This mixture is 

 at first of a violet colour, grows afterwards red, and when 

 the red particles come into closer contact with one another, 

 the red colour disappears, and the powder precipitated has 

 the natural colour of manganese, (c) The same thing 

 happens if the blue solution of manganese be mixed with a 

 few drops of an acid, or if the solution has been exposed for 

 a few days to the open air; the caustic alkali in this case 

 unites with the aerial acid, which is present in large quantity 

 in the atmosphere, and for this reason the manganese must 

 also fall down, (d) Probably the fine particles of manganese 

 have naturally a dark red colour, which becomes visible 

 when they are separated from one another, without, however, 

 being perfectly dissolved in a menstruum, (e) The precipit- 

 ate produced by an acid is still real manganese a part of 

 which is soluble in acid of vitriol, but not the whole (Sec. 

 II. (ay), unless there be added some phlogiston. Hence it 

 follows that nitre is not capable of depriving the manganese 

 of its natural small quantity of phlogiston (Sec. xv.) ; con- 

 sequently the alkalisation of nitre cannot be ascribed to the 

 natural phlogiston of the manganese. (/) If the solution 

 (a) be mixed with diluted vitriolic acid to saturation, the 

 red colour disappears, and the solution grows colourless. 

 The reason of this is, because there is always some undecom- 

 posed nitre in the alkali of nitre, the acid of which has taken 

 some phlogiston from the red heat (Sec. VIL). This phlogistic- 

 ated nitrous acid is in the present case separated from its 

 alkali by the vitriolic acid, and dissolves the manganese 

 according to the reasons mentioned in Sees, xx., xxn. (g) 

 Manganese fused with alkali of tartar has nearly the same 

 properties with that treated with nitre, the last excepted 

 from the want of sulphur. (A) If charcoal in powder be 

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