ON MANGANESE 79 



till the mixture grows red hot. (a) If phlogisticated man- 

 ganese be mixed with an equal quantity of pure nitre, and 

 distilled in a glass retort provided with a receiver, it is 

 observable that the mixture begins to grow black before the 

 retort becomes red hot, but no nitrous acid goes over. If 

 it be afterwards lixiviated, there appears no mark of any 

 uncombined alkali in the lixivium ; but, on mixing the 

 solution with tamarinds, an odour of aquafortis immediately 

 arises. (b) If three parts of phlogisticated manganese, 

 mixed with one part of finely powdered nitre, be distilled 

 in the same manner, but the distillation be stopped as 

 soon as the mixture grows black, the nitre is found to be 

 alkalised ; no nitrous acid, however, is found in the receiver. 

 All this proves clearly that phlogiston is contained in 

 manganese. 



SECTION XXXVI. 



I likewise examined the effects produced on manganese 

 by unctuous oils and inflammable bodies. 



(a) One part of finely powdered manganese digested with 

 four parts of olive oil underwent no change ; but as soon as 

 the oil grew hotter, the mass began to effervesce violently, 

 which is owing to the extrication of aerial acid. After the 

 mass was become cold, the manganese was found to be 

 dissolved, and had the consistence of salve, (b) A mixture 

 of finely powdered manganese and charcoal was distilled in 

 a small glass retort, to which an empty bladder was tied. 

 When the retort began to melt, a quantity of aerial acid was 

 extricated, and filled the bladder (Sec. XXIL). The remainder 

 in the retort was for the greatest part soluble in spirit of 

 vitriol, without the addition of any phlogiston. Spirit of 

 wine, ether, oil of turpentine produced no change upon 

 manganese by themselves. 



