This sublimate will render blue a slip of red litmus paper.  This can be easily done by moistening the litmus paper, and then inserting the end of it in the tube.  By holding a glass rod, moistened with dilute hydrochloric acid, over the mouth of the tube, a white vapor is instantly rendered visible (sal ammoniac).

(d.) Lithia (LiO).—­In the pure state, lithia is white and crystalline, not easily soluble in water, and does not absorb moisture.  It changes red litmus to blue, and at a low red heat it melts.  Lithia or its salts, exposed to the point of the blue flame, communicates a red color to the external or oxidation flame, in consequence of a reduction, sublimation, and re-oxidation of the lithia.  An admixture of potash communicates to this flame a reddish-violet color, and the presence of soda that of a yellowish-red or orange.  If the soda, however, is in too great proportion, then its intense yellow hides the red of the lithia.  In the latter case the substance under test must be only imperfectly fused in the oxidation flame, and then dipped in wax or tallow.  By exposing it now to the reduction flame, the red color imparted to the external flame by the lithia becomes visible, even if a considerable quantity of soda be present.  A particular phenomenon appears with the phosphate of lithia, viz., the phosphoric acid itself possesses the property of communicating to the flame a bluish-green color.  By its combination with lithia it still exhibits its characteristic color, while the latter presents likewise its peculiar tint.  Then we perceive a green flame in the centre of the flame, while the red color of lithia surrounds it.

The silicates, which contain only a little lithia, produce only a slight hue in the flame, and often none at all.  We have to mix one part of the silicate with two parts of a mixture composed of one part of fluorspar and one and a half parts of bisulphate of potassa.  Moisten the mass with water so that the mass will adhere, and then melt it upon a platinum wire in the reduction flame, when that of oxidation will present the red color of lithia.

The Borates of lithia produce at first a green color, but it soon yields to the red of lithia.  When alcohol is poured over lithia or its compounds, and inflamed, it burns with a deep red color, particularly if the fluid is stirred up with a glass rod, or when the alcohol is nearly consumed.  This color presents the same modifications as the corresponding ones communicated to the blowpipe as mentioned above.

The salts of lithia are absorbed by charcoal when fused upon it.  The sulphide, bromide, iodide, and chloride of lithia produce upon the charcoal a greyish-white sublimate, although not so copiously as the corresponding compounds of potash and soda.  This sublimate disappears when touched by the reduction flame, while the oxidation flame gives the characteristic color of lithia.

SECOND GROUP.—­THE ALKALINE EARTHS, BARYTA, STRONTIA, LIME, AND MAGNESIA.