Vanadic Acid (VO^{3}) fuses upon platinum foil to a deep orange liquid, which becomes crystalline after cooling.  When fused upon charcoal, one part of it is absorbed, while the rest remains upon the charcoal and is reduced to protoxide similar in appearance to graphite.

A small portion of it fuses with borax in the oxidation flame to a clear colorless bead, which appears, with the addition of more vanadic acid, of a yellow color, but changes to green when cold.

In the reduction flame the bead is brown while hot, but changes, upon cooling, to a beautiful sapphire-green.  At the moment of crystallization, and at a degree of heat by which at daylight no glowing of the heated mass is visible it begins to glow again.  The glow spreads from the periphery to the centre of the mass, and is caused by the heat liberated by the sudden crystallization of the mass.  It now exhibits an orange color, and is composed of needle crystals in a compact mass.

Microcosmic salt and vanadic acid fuse in the oxidation flame to a dark yellow bead which, upon cooling, loses much of its color.

In the reduction flame the bead is brown while hot, but, upon cooling, acquires a beautiful green color.

Vanadic acid fuses with carbonate of soda upon charcoal, and is absorbed.

(k.) Chromium (Cr) occurs in the metallic state only in a very small quantity in meteoric iron, but is frequently found in union with oxygen, as oxide in chrome iron ore, and as chromic acid in some lead ores.

In the metallic state it is of a light grey color, with but little metallic lustre, very hard, and not very fusible.  Acids do not act upon it, except the hydrofluoric; fused with nitre, it forms chromate of potassa.  It is unaltered in the blowpipe flame.

Sesquioxide of Chromium (Cr^{2}O^{3}).—­This oxide forms black crystals of great hardness, and is sometimes seen as a green powder.  Its hydrate (Cr^{2}O^{3} + 6HO) is of a bluish-grey color.  It forms with acids two classes of isomeric salts, some of which are of a green color, and the others violet-red or amethyst.  The neutral and soluble salts have an acid reaction upon blue litmus paper, and are decomposed by ignition.

Sesquioxide of chromium in the oxidation and reduction flames is unchangable.  When exposed to heat, the hydrate loses its water, and gives a peculiarly beautiful flame.  In the oxidation flame borax dissolves the sesquioxide of chromium slowly to a yellow bead (chromic acid) which is yellowish green when cold.  Upon the addition of more of the oxide, the bead is dark red while hot, but changes to green as it becomes cold.

In the reduction flame the bead is of a beautiful green color, both while hot and when cold.  It is here distinguished from vanadic acid, which gives a brownish or yellow bead while hot.

With microcosmic salt it fuses in the oxidation flame to a clear yellow bead, which appears, as it cools, of a dirty-green, color, but upon being cool is of a fine green color.  If there be a superabundance of the oxide, so that the microcosmic salt cannot dissolve it, the bead swells up, and is converted into a foamy mass, in consequence of the development of gases.