Quartz compound

Usage examples of silica.

The two lots of silica are washed free from chlorides with hot water, dried on an air-bath, transferred to a platinum-crucible, ignited gently at first, at last strongly over the blast or in a muffle, cooled in a desiccator, and weighed.

The silica is washed by decantation two or three times with hydrochloric acid and hot water, before being thrown on to the filter.

The smoke thus produced reduces the red ferric oxide to blue-green ferrous oxide, or to metallic iron, which combines with the silica present to form a fusible ferrous silicate.

As the tide rose each piece was trundled on to the sloping beach, to be rolled and compressed until coated with a mosaic of white shell chips, angularities of silica and micaceous spangles, the finished article being cast aside as the tide receded.

Silicon fluoride is evolved, and, if a moistened glass rod is held in the tube, it becomes coated with a white deposit of silica, formed by the decomposition of the silicon fluoride by the water.

On holding a rod, moistened with a drop of water, over the escaping fumes, the white crust of silica formed on the drop of water shows its presence.

The residue may consist of unremoved silica, and oxides of tantalum, niobium, and, perhaps, chromium.

To prevent the photoactivity, modern pigmentary TiO2 is coated with silica.

Boussingault has shown that this is due to the formation of a silicide of platinum by means of the reduction of the silica of the carbon by the metal.

This may readily be done by adding terbium oxide with a little xerion to the silica.

Firstly, the silica contains a new catalyst, terbium oxide, one of the rare earths.

Ojo Caliente was constantly being reshaped and rebuilt, in places spongy, in other places cracked and hard and brittle, the stuff of geyserite: a hydrous form of silica, a variety of opal deposited in gray and white concretelike masses, porous, filamentous, and scaly.

The thinness of the silica layer is critical: it has to be just thick enough to block the photocatalysis, but not so thick that it degrades the optical properties of the TiO2.

After Silica, if the discharge continues too long and the wound refuses to heal owing to a torpidity of the tissues.

All clays contain more or less free silica in the form of sand, and usually a small percentage of undecomposed felspar.