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Mr. Davy on some 
in nitro-muriatic acid, and in cold muriatic acid, but it slowly 
dissolves in this last acid by the assistance of heat. It is not 
acted upon by a strong solution of the fixed alkalies. When 
the oxide is put into liquid ammonia, minute globules of air 
are evolved from it, but the quantity has been too small to 
admit of being examined; probably it is common air, as the 
oxide appears to undergo no change by being kept for some 
weeks in ammonia. When heated with sulphur, the oxide 
yields sulphureous acid gas and a grey sulphuret of pla- 
tinum. When mixed with zinc filings and heated, the oxide 
is decomposed with vivid ignition, and white oxide of zinc 
is formed. 
When the oxide is mixed with borax, and exposed to a 
strong red heat before the blowpipe, it forms a black glass, 
which becomes of a lighter colour on urging the heat to 
whiteness, and the oxide appears to be reduced. If the oxide 
is mixed with powdered glass and fused, a glass is obtained 
of a dull brown colour. The oxide is readily reduced by 
moistening it with oil of turpentine, and heating it moderately ; 
or by exposing it to a dull red heat in the atmosphere ; but it 
requires a strong red heat to reduce it in close vessels. Some 
of the oxide which had been well dried, first on a hot sand 
bath, and then exposed to a heat just below redness, on a slip of 
platinum, w'as decomposed in very small green glass retorts, 
over mercury. In two experiments in which I used 7 grains 
of the oxide, l obtained in each instance 6 grains of platinum, 
and g*i cubic inches of oxygen, the thermometer being at 
6o° and barometer 30®. I found also in the necks of the re- 
torts, a slight trace of a fluid that reddened litmus paper, 
and had an odour similar to that of nitrous acid. Now, if 
