56 ESSAY V. 



united with the black mass above mentioned. The manganese 

 was thus entirely dissolved in a few hours' time ; the solution 

 was as limpid as water, a little fine earth excepted, which 

 was siliceous. There began now to precipitate a white 

 earth, of the same kind as that mentioned in Sec. iv. (6). 

 In other respects, this solution agreed with that made in 

 pure nitrous acid, as it is described in the preceding 

 paragraph. 



SECTION VI. EFFECTS OF COMMON MURIATIC ACID. 



(a) I poured 1 oz. of purified muriatic acid upon half an 

 ounce of levigated manganese. This acid, after standing 

 quiet for an hour's time, grew dark brown. A portion of 

 this solution was digested in an open glass vessel in heat. It 

 yielded a smell like warm aqua regia. In a quarter of an 

 hour the smell was gone, and the solution became clear and 

 colourless, (b) The rest of the brown solution was digested, 

 with -a view to see whether the muriatic acid would be 

 saturated with manganese. As soon as it grew warm, the 

 smell of aqua regia was considerably stronger, and an 

 effervescence ensued, which lasted till the next day, when 

 the solution was found saturated. Upon the residuum which 

 was not dissolved I poured another ounce of muriatic acid, 

 which was followed by the very same phenomena, and the 

 manganese was entirely dissolved, a small quantity of 

 siliceous earth remaining, (c) This yellow solution was 

 divided into two portions. Into the one I poured some 

 drops of vitriolic acid, and the solution in a few minutes 

 turned white, and a fine powder was precipitated, which was 

 not soluble in water. After the solution was evaporated, 

 some small selenitic crystals formed, and the residuum 

 exhibited the same phenomena as are described above with 



