160 
METALLIC OXI0E5. 
Oxides of tin. taining the just point of saturation considerably great, these 
sort of analytical experiments are not to be confided in. 
The following experiments, perhaps/deserve a little more con- 
fidence. I prepared a saturated solution -of the oxide of tin 
in caustic kali, which was precipitated by means of water of 
barytes. The precipitate was white, flaky, and very voluminous. 
I washed and dried it very quickly. A part, treated while 
still wet, with muriatic acid, was decomposed without effer- 
vescence ; another part, dried and heated to a red heat, in a 
platina crucible, became of a fine lemon colour, and, when 
treated with muriatic acid, it produced a strong effervescence. 
Four grammes of this red mass produced three grs. of the 
oxide, and 0/9 grs. of barytes. The four grammes which 
are wanting, is carbonic acid, and corresponds almost exactly 
with the barytes. The oxide contains 65*4 parts of oxigen, 
8'3 parts of barytes — that is to say, the first contains eight 
times as much as the latter. The mixture of the carbonate of 
barytes, and the oxide of tin, at red heat, preserved even in 
the highest temperature that I could give it, its yellow colour, 
probably because the carbonic acid prevents the action of the 
alkaline earth on the oxide, by means of which it would have 
been reduced to the intermediate degree j but, at the points 
where the mixture had been in contact with the carbon, it had 
become white. 
Lime-water precipitated the stannate of kali in the same 
manner as the water of barytes. The stannate of lime readily 
attracted the carbonic acid of the air j it turned yellow at a 
cherry red heat, and soon became white, without the influence 
of any combustible body when it was exposed to a bright red 
heat. 
The stannate of kali, used in order to precipitate the metallic 
solutions, produced the following results : 
In the plumbic nitrate, it gave a white precipitate, which 
afforded a small quantity of water when at a red heat, and was 
changed to a straw colour. 
In the cobaltic muriate, it gave a blueish precipitate, which, 
when washed in boiling water, became red ; and, by drying, 
changes to a deep brqwn, and of a vitreous fracture. At a red 
heat it loses water, and turns black, giving to paper the colour 
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