The same decomposition may be effected by igniting with iron, ferric oxide and sodium carbonate (E.
After two or three hours the liquid is diluted till its density falls to 1.23, when it is passed through filter-presses to remove the insoluble ferric oxide and silica.
To tin cast-iron articles they must be decarburetted superficially by ignition within a bath of ferric oxide (powdered haematite or similar material), then cleaned with acid, and tinned by immersion, as explained above.
He inferred that chromic acid must contain only three atoms of oxygen, as did sulphuric acid SO 3; consequently chromic oxide, which contains half the amount of oxygen, must be Cr 2 O 3, and hence ferric oxide must be Fe203.
The iron and aluminium precipitates are filtered off, and the filtrate boiled, when a basic beryllium hydroxide containing a little ferric oxide is precipitated.
This iron deposit is not merely mechanical but is due to the physiological activity of the organism which, according to Winogradsky, liberates energy by oxidizing ferrous and ferric oxide in its protoplasm - a view not accepted by H.
By converting ferrous into ferric oxide the green tint is changed to yellow, which is less noticeable.
Among such substances are fireclay and firebricks, certain sandstones, silica in the form of ganister, and Dinas stone and bricks, ferric oxide and alumina, carbon (as coke and graphite), magnesia, lime and chromium oxide - their relative importance being indicated by their order, the last two or three indeed being only of limited use.
The function of the ferric oxide present in ordinary cement is little more than that of a flux to aid the union of silica, alumina and lime in the clinker; its role in the setting of the cement is altogether secondary.
If the substance does not melt but changes colour, we may have present: zinc oxide - from white to yellow, becoming white on cooling; stannic oxide - white to yellowish brown, dirty white on cooling; lead oxide - from white or yellowish-red to brownish-red, yellow on cooling; bismuth oxide - from white or pale yellow to orange-yellow or reddish-brown, pale yellow on cooling; manganese oxide - from white or yellowish white to dark brown, remaining dark brown on cooling (if it changes on cooling to a bright reddishbrown, it indicates cadmium oxide); copper oxide - from bright blue or green to black; ferrous oxide - from greyish-white to black; ferric oxide - from brownish-red to black, brownish-red on cooling; potassium chromate - yellow to dark orange, fusing at a red heat.