It forms a dark-violet precipitate which dries to a greyish-violet powder.
The acacias and the Rosaceae yield their gums most abundantly when sickly and in an abnormal state, caused by a fulness of sap in the young tissues, whereby the new cells are softened and finally disorganized; the cavities thus formed fill with liquid, which exudes, dries and constitutes the gum.
That which dries on the incisions in the tree is called " bola " or " burucha," and is said to be highly prized in New York.
Stannous sulphide, SnS, is obtained as a lead-grey mass by heating tin with sulphur, and as a brown precipitate by adding sulphuretted hydrogen to a stannous solution; this is soluble in ammonium polysulphide, and dries to a black powder.
On the llanos the dry season destroys the pasturage completely, dries up the small streams and lagoons, and compels many animals of semi-aquatic habits to aestivate.
