Baryta and its compounds fuse when exposed to ignition in the oxidizing flame.  Moistened with the solution of nitrate of cobalt, and heated in the oxidation flame, it presents a bead, colored from brick-red to brown, according to the quantity used.  This color disappears when cold, and the bead falls to a pale grey powder after being exposed awhile to the air.  When heated again, the color does not appear until fusion is effected.  If carbonate of soda is fused upon platinum wire with so much of the sesquioxide of manganese that a green bead is produced, this bead, when fused with a sufficient quantity of baryta, or its compounds, after cooling, will appear of a bluish-green, or light blue color.

(b.) Strontia (SrO).—­Strontia and its compounds are analogous to the respective ones of baryta.  The hydrate of strontia has the same properties as the hydrate of baryta, except that it is less soluble in water.  The carbonate of strontia fuses a little at a red heat, swells, and bubbles up like cauliflower.  This produces, in the blowpipe flame, an intense and splendid light, and now produces an alkaline reaction upon red litmus paper.  The sulphate of strontia melts in the oxidation flame upon platinum foil, or upon charcoal, to a milk-white globule.  This fuses upon charcoal, spreads and is reduced to the sulphide, which is absorbed by the charcoal.  It now produces the same reactions upon polished silver as the sulphate of baryta under the same conditions.  By exposing strontia and its compounds upon platinum wire, or as a splinter with the platinum tongs, to the point of the blue flame, the external flame appears of an intense crimson color.  The deepest red color is produced by the chloride of strontium, particularly at the first moment of applying the heat.  After the salt is fused, the red color ceases to be visible in the flame, by which it is distinguished from the chloride of lithium.  The carbonate of strontia swells up and produces a splendid white light, while the external flame is colored of a fine purple-red.  The color produced by the sulphate of strontia is less intense.  The presence of baryta destroys the reaction of the strontia, the flame presenting the light green color of the baryta.

If alcohol is poured over powdered strontia and inflamed, the flame appears purple or deep crimson, particularly if the fluid is stirred with a glass rod, and when the alcohol is nearly consumed.

The insoluble salts of strontia do not produce a very intense color.  Baryta does not prevent the reaction of the soluble salts of strontia, unless it exists greatly in excess.  In the presence of baryta, strontia can be detected by the following process:  mix some of the substance under examination with some pure graphite and water, by grinding in an agate mortar.  Place the mixture upon charcoal, and expose it for a while to the reduction flame.  The substance becomes reduced to sulphide of barium and sulphide of strontium, when it should be dissolved in hydrochloric acid.  The solution should be evaporated to dryness, redissolved in a little water, and enough alcohol added that a spirit of 80 per cent. is produced.  Inflame the spirit, and if strontia is present, the flame is tinged of a red color.  This color can be discerned more distinctly by moistening some cotton with this spirit and inflaming it.