ON MANGANESE 55 



as much powdered manganese as was necessary for the 

 perfect saturation of the acid, and found that 9 drms. were 

 required for this purpose. (I) The solution of manganese, 

 being by these means saturated, was filtered and divided into 

 two equal portions. Into one of these I poured some drops 

 of vitriolic acid, whereby a fine powder was precipitated, 

 which, however, did not settle at the bottom till after some 

 hours had elapsed. This powder was neither soluble in 

 boiling water nor in acids. The limpid solution, after being 

 evaporated, yielded some small crystals of selenite or gypsum ; 

 but would afford no others, (c) From the other half of this 

 solution, after it had been evaporated in a gentle heat, I 

 obtained small shining crystals, which, as well as the solution 

 itself, were of a bitter taste, and weighed about 10 grs. On 

 pouring some drops of vitriolic acid into this solution, 

 inspissated by a gentle heat, no precipitation ensued, except 

 of a little selenite ; but as soon as it was inspissated to the 

 consistency of honey, some fine acicular crystals, verging 

 towards the same centre, began to form, but they grew soft 

 and deliquesced in a few days afterwards. 



SECTION V. EFFECTS OF PHLOGISTICATED NITROUS ACID. 



As this acid shows, in several experiments, quite different 

 phenomena from those which the pure nitrous acid shows, 

 I purposed to try its effects also upon manganese. I 

 therefore put a little levigated manganese, mixed with some 

 water, into a large receiver, to which I luted a tubulated 

 retort, and poured through the opening some ounces of 

 common nitrous acid, and added, at several different times, 

 some iron filings, taking care to close the vessel always with 

 a glass stopple. The nitrous acid thus combined with the 

 phlogiston of the iron went over into the receiver, and there 



