It is a colourless, amorphous solid, which is almost insoluble in water, its solubility diminishing with increasing temperature; it is appreciably soluble in concentrated sulphuric acid.
It is a reddish amorphous mass, insoluble in alcohol, and when distilled yields picoline (methyl pyridine) (A.
Allotropic Modifications.-Sulphur assumes crystalline, amorphous and (possibly) colloidal forms. Historically the most important are the rhombic (Sa) and monoclinic (So) forms, discussed by E.
Haemosiderin, an iron-containing pigment (probably an hydrated ferrous oxide), is found in more or less loose combination with protein substances in an amorphous form as brownish or black granules.
The specific gravity of the amorphous form is 2.35 (Vigouroux), that of the crystalline variety varying, according to the method of preparation, from 2.004 to 2.493.
On warming solutions of pyrrol in dilute acid, ammonia is evolved, and an amorphous powder of variable composition, known as pyrrol-red, separates out.
The dichloride, WC1 2, is an amorphous grey powder obtained by reducing the hexachloride at a high temperature in hydrogen, or, better, by heating the tetrachloride in a current of carbon dioxide.
White lead is an earthy, amorphous powder.
The mineral is also frequently found massive, with a coarse or fine granular structure and a crystalline fracture; sometimes it occurs as a soft, white, amorphous deposit resembling artificially precipitated zinc sulphide.
Calcium monosulphide, CaS, a white amorphous powder, sparingly soluble in water, is formed by heating the sulphate with charcoal, or by heating lime in a current of sulphuretted hydrogen.