31 S METALLIC OXIDES. 



potash could be so dissolved ; a white powder was then left, 

 which I dried upon blotting paper. One part of this powder 

 boiled for some hours with water was dissolved, and I passed 

 the solution through the filter. The filtered liquid had a 

 slightly bitter taste, rather metallic. It restored the blue of 

 turnsole paper, which had been reddened by a weak acid, and 

 the smallest quantity of a diluted acid caused a precipitate 

 which was notredissolved in the fluid. The precipitate afford- 

 ed by the acetic acid, well washed, was white and tasteless ; 

 but it reddened turnsole paper, although the filtered solution 

 had not yet lost the property of acting like a weak solution of 

 alkali. The while precipitate caused by passing a current of 

 carbonic acid gas through the alkaline liquor, had the same 

 property of reddening turnsole paper j a property which con- 

 sequently belongs to the precipitated oxide, and cannot be 

 owing to the combination with the acid, which served to pre- 

 cipitate it. The dry precipitate did not, in several months, 

 lose the property of re-acting like an acid upon vegetable co- 

 lours. But when I heated it in a retort over the flame of a spirit 

 lamp, a quantity of water was disengaged, which did not red- 

 den them, and was very pure j and the yellow oxide which 

 remained had lost the property of reddening turnsole paper, 

 deprived of its One part of the saline solution, evaporated in a silver cru- 

 anhydrhTsti- c »We, left a white mass. 1 decomposed this by digesting it 

 fciate. with diluted nitric acid, by successive operations, to extract the 



potash. The undissolved oxide was white. I washed it with 

 much water, and at las|j dried it at the temperature of boiling 

 water j and then I heated certain portions, previously weighed, 

 in order first to drive off the remaining water, and next the 

 oxigen, until the white oxide only should remain. Jn several 

 experiments 100 parts left 88'3, 887 and 88'9 p. of white 

 oxide. The quantity of oxigen combined with 88'7 p. of the 

 white oxide, in order to form the yellow oxide, is, from what 

 we have determined, 6 45 j and therefore the quantity of water 

 was only 4°78. But 959,2 p. of yellow oxide contain 2581 

 p. of bxigen, and 4'78 of water contain 4"218 ; now, 4*218 x 

 6=25*3 It follows, therefore, that t,he white powder not 

 dissolved by the nitric acid, is an hydrique stibiate, that is to 

 say, a combination of stibic oxide, with water, as its base, and 

 jn which the acid contains six times as much oxigen as water. 



The 



