Commercial iodine may be purified by mixing it with a little potassium iodide and then subliming the mixture; in this way any traces of bromine or chlorine are removed.
It forms white plates, melting at 132°, readily soluble in water, and subliming without decomposition.
Soc. chim., 1879, 32, p. 14) on subliming ordinary sulphur.
It may be obtained direct from pure and bright coloured portions of the native ore cinnabar, or, artificially, by subliming a mixture of mercury and sulphur.
A sublimate may be formed of: sulphur - reddish-brown drops, cooling to a yellow to brown solid, from sulphides or mixtures; iodine - violet vapour, black sublimate, from iodides, iodic acid, or mixtures; mercury and its compounds - metallic mercury forms minute globules, mercuric sulphide is black and becomes red on rubbing, mercuric chloride fuses before subliming, mercurous chloride does not fuse, mercuric iodide gives a yellow sublimate; arsenic and its compounds - metallic arsenic gives a grey mirror, arsenious oxide forms white shining crystals, arsenic sulphides give reddish-yellow sublimates which turn yellow on cooling; antimony oxide fuses and gives a yellow acicular sublimate; lead chloride forms a white sublimate after long and intense heating.
He does not tell us how it was prepared, but he describes the method of subliming it, which can leave no doubt that it was real sal ammoniac. In the Opera mineralia of Isaac Hollandus the elder, there is likewise a description of the mode of subliming sal ammoniac. Basil Valentine, in his Currus triumphalis antimonii, describes some of the peculiar properties of sal ammoniac in, if possible, a still less equivocal manner.
The subliming apparatus consists of two parts: (I) a hemispherical stoneware basin placed within a closefitting iron one, or an enamelled iron basin, and (2) a hemispherical lead or stoneware lid, or dome, cemented on the top of the basin to prevent leakage.
It is obtained by passing ammonia gas over hot coal; by subliming a mixture of ammonium chloride and potassium cyanide; by passing a mixture of ammonia gas and chloroform vapour through a red hot tube; and by heating a mixture of ammonia and carbon monoxide: CO+2NH 3 = NH 4 NC+H 2 0.
Aluminium fluoride, AlF 3, obtained by dissolving the metal in hydrofluoric acid, and subliming the residue in a current of hydrogen, forms transparent, very obtuse rhombohedra, which are insoluble in water.
Kahlbaum succeeded in subliming the metal in a vacuum, and H.
ORPIMENT (auripigmentum), arsenic trisulphide, As2S3, or yellow realgar, occurring in small quantities as a mineral crystallizing in the rhombic system and of a brilliant goldenyellow colour in Bohemia, Peru, &c. For industrial purposes an artificial orpiment is manufactured by subliming one part of sulphur with two of arsenic trioxide.
The tri-iodide, AsI3 prepared by subliming arsenic and iodine together in a retort, by leading arsine into an alcoholic iodine solution, or by boiling powdered arsenic and iodine with water, filtering and evaporating, forms brick-red hexagonal tables, of specific gravity 4.39, soluble in alcohol, ether and benzene, and in a large excess of water; in the presence of a small quantity of water, it is decomposed with formation of hydriodic acid and an insoluble basic salt of the composition 4AsOI.