Amorphous, or red Phosphorus is an allotropic) variety that has long been known to chemists, but has been extensively manufactured only since the year 1848. It is most easily made by keeping ordinary phosphorus for several days at a temperature of 450° or 460° Fehr. It forms a red or purple friable amorphous mass. Its specific gravity melting point and igniting point are higher than ordinary phosphorus. It is insoluble in bisulphide of carbon, is neither dangerously inflam mable nor poisonous, and does not communicate to the workpeople engaged In handling it, that painful disease of the jaws that ordinary phosphorus imparts. These properties have secured fur it extensive use in the manufacture of Weiler matches, and it was at ono time hoped that it would quite supersede tho white variety • unfortunately however, it gradually attracts oxygen from the airandthe phosphorous and phosphoric acids produced are so exceedingly deliquescent that matcher prepared with amorphous phosphorus are liable to become damp.
Black Phosphorus is another amorphous variety of this element. It is obtained by very suddenly cooling melted phoaphorus.
The equivalent of phosphorus is 32.
Oxygen and Phosphorus combine with great readiness, and form four distinct compounds, namely : 1. Osida of phosphors 1. Itapepaospaorcen acid . . . . . 1.0 3. Phosphorous acid PO, 4. rboophono acid Po, 1. Oxide of Phosphorus.—This Is prepared by melting phosphorus in hot water, and in this state forcing a jet of oxygen gas upon it. The phosphorus burns under water, and the results are phosphoric acid, which remains in solution, and which we shall presently describe, and a red pulverulent body, which remains at the bottom of the vessel, and is the oxide of phosphorus. It is inodorous and tasteless, and is insoluble in water, alcohol, ether, or oiL It undergoes no change in the air, even when heated to above 600' Fahr. ; but at a low red heat it burns. In chlorine gas it inflames. It decomposes nitric acid readily, and combining with its oxygen, becomes phosphoric acid. It does not possess either acid or alkaline properties.
2. Ilypophosphorous Acid was discovered in 1816 by M. Dt:long. When phosphide of barium is acted upon by water, both suffer decom position, and there are formed phosphuretted hydrogen, phosphoric acid, hypopliosphorous acid, and baryta; the earth combines with both the acids, and the phosphate of baryta being insoluble, is precipitated, while the hypophoephite is soluble, and sulphuric acid being added to the solution, sulphate of baryta is precipitated, and free hypophos phorous acid remains in solution ; by evaporating this, a viscid strongly acid substance is obtained, which is hydrated hypophosphorous acid.
Hypophosphorous acid is liquid, uncrystallisable, has a powerful taste, is heavier than water, and cannot be obtained in a dry state. When subjected to the action of heat, it is quickly decomposed into phosphuretted hydrogen gas, which escapes, and phosphorous and phosphoric acids. Water dissolves this acid in all proportions ; it acts very powerfully as a deoxidising agent, but nevertheless combines with many salifiable bases, forming ealts which lire termed hypophosphites ; these salts are remarkably soluble in water; they are usually deli quescent, and crystallise with great difficulty. From the circumstance that neither this acid nor its ealta can be obtained free from water, its true formula is probably P11,0,, that is phosphoric acid in which two atoms 'of oxygen are replaced by two of hydrogen.
3. Phosphorous Acid, like the preceding, is entirely an artificial product; it is obtained in the greatest purity by subliming phosphorus through bichloride of mercury in a glass tube. During the action of the heat, the phosphorus takes half the chlorins from the mercury, and they form a volatile compound which condenses into limpid liquid chloride of phosphorus : when this is mixed with water, mutual decomposition occurs ; the hydrogen of the water and the chlorine of the chloride form hydrochloric acid, while the oxygen and phosphorus unite to form phosphorous acid. By evaporation thalydrochloric acid is expelled, and when evaporation has been continued until the residue, while hot, has the consistence of a syrup, it becomes a solid crystalline mass on cooling, which is hydrated phosphorous acid. This acid dissolves very readily in water, has a sour taste, reddens vegetable blue colours, and combines with some bases to form salts, which are called phosphite,.
Phosphorous acid is also formed when phosphorus is burnt in rarefied air. When phosphorus is exposed to air and moisture, it has been lung known that a dense sour fluid is formed by the absorption of oxygen : this was supposed by M. Dulong to he a peculiar acid, and he allied it phosphatic acid ; it was however subsequently shown by Davy to be a mixture of phosphorous and phosphoric acids.
Phosphite of A uunonta is procured by adding carbonate of ammonia to the acid to saturation. It crystallises in deliquescent needles; when heated, it is decomposed, giving out ammonia; and by the continued application of heat, the phosphorous acid remaining is converted into phosphoric acid. It is nut a salt of any importance.