METALLIC OXIDES. 
129 
by the nitric acid. This intermediate degree can be no other than Oxides of, tin, 
the multiplication by l^, and by the numerous examples we 
already know of this series, it appears that we do not require 
any special analysis, which at least would be very difficult to 
effect, in order to determine the composition of the interme- 
diate oxide, as follows : 
Tin 83*13 100*0 
Oxigen 16 8/ 20 4 
The distinctive characters of the oxide at a maximum are 
the following : Digested with a lixivium of carbonate of al- 
kali, it does not dissolve, but part of the alkali is combined 
with the oxide ; but when the excess of alkali is taken from 
it along with the lixivium, the combination of the oxide with 
the alkali is soluble in pure water, and forms a milky fluid, 
which, after the deposition of the part not dissolved, is yellow. 
When this liquor is evaporated, it leaves a yellow jelly, which, 
' in its dry state, is full of cracks, and has some resemblance to 
amber. It is soluble again in cold water. The liquor here 
mentioned is precipitated by both alkalis and acids. The sul- 
phuric, nitric, acetic, and oxalic acids in excess do not reduce 
the precipitated oxide. If this oxide be mixed with concen- 
trated sulphuric acid, it gains in volume, becomes yellow, but 
does not dissolve. The yellow powder seems to be a combi- 
nation with the acid ; it is easily decomposed by means of 
water, which takes up the acid, and leaves the oxide its white 
colour. This oxide wiil combine with muriatic acid, and an 
excess of acid renders it insoluble in water. The neutral combi- 
nation is easily dissolved by it, but is precipitated by an addition 
of muriatic acid, and is decomposed at a point of temperature 
which is not as high as boiling water. The oxide is deposited 
by coagulating, and the fluid becomes a mass exactly resembling 
coagulated albumen. The oxide at a maximum, combines with 
water, and it is then white, but on being exposed to heat, it 
gave back the water, and became yellow. It produced no alter- 
ation in it when exposed to the highest temperature possible, 
in a covered crucible of Platina Urged by the flame before a 
blow pipe, it became white at the part where the point of the 
flame touched it. Is this a reduction of the intermediate 
©xide - 3 and is the white enamel, which is obtained by melting^ 
Vol.XXXV.— N o. 162. K the 
