In 1851, Dr. Schrotter made known the mode of preparation on a large scale, and the properties of this kind of phosphorus isomeric with the white one.

Properties

Amorphous phosphorus has a violaceous brown-red color, opalescent, hard, easy to pulverize. Its specific gravity = 1.964 at the temperature of 50°, whilst at the same temperature the specific gravity of the ordinary phosphorus = 1.830. It becomes luminous at 392°, is not inflammable in the air except if its temperature is above 392°; and a remarkable phenomenon is that it will burn under the influence of direct solar rays at a temperature of 131°. It can be preserved in the air with-out alteration, and sulphuret of carbon, ether, naphtha, and alcohol cannot dissolve it. This variety, hardened by a prolonged heat, is more resisting, and has that very remarkable property of not being venenous, and of being inflamed in the air by rubbing in presence of chlorate of potash. These two properties explain the utility of its application in the fabrication of matches.

Preparation

To obtain amorphous phosphorus according to Schrotter's process, the white phosphorus must be kept in a close vessel at the temperature of 536° for from eight to twelve days, heating it very gradually for two days, a little above 464°, to avoid the ebullition of the phosphorus. Then heat by degrees up to 536°, being careful not to exceed this point, for amorphous phosphorus will bo reduced into vapors, and form again the ordinary phosphorus. These conditions are realized with three concentric receivers of cast-iron, having the form of crucibles. The largest one constituting a water-bath, containing an alloy of equal parts of lead and tin. The second vessel dipped in this one contains powdered sand forming a sand-bath, in which is placed the third vessel, which last one contains the phosphorus, and transmits the temperature received by the intermediary of the two baths of alloy and sand.

Schrotter placed in this third vessel, a china vessel, having a similar form, and this latter receives the phosphorus.

A cast-iron covercle is adapted to the third vessel; this covercle is maintained by a screw, which presses strongly on the centre. In all cases, the covercle of the third vessel Las a furrow in which is fitted the threaded end of a copper tube curved as a syphon; and of which the opposite end goes into a little kettle containing mercury. This pipe is provided with a faucet to shut off the communication between the receiver and the mercury when the operation is completed. During all the time that, with the help of the two baths, the temperature is maintained at 536°, a little lamp should be placed under the tube to keep the temperature sufficiently high to liquefy the phosphorus which can be carried away by the phosphuretted hydrogen gas, and will shut the tube if not heated.

After gradually heating the double bath to disengage the air and vapor of water, raise the temperature till disengagement of vapors which burn in the air. One or two hours after, raise the temperature 392°, then to 464°, and at last to 536°, and keep it at this point for ten days.

M. Coignet, of Lyons, has done away with the bath. He heats the phosphorus directly with the same care in a cast-iron vessel which holds 400 pounds. Five similar vessels, holding together 2000 pounds of phosphorus, or 4000 in one month can furnish enough for the entire consumption of the United States at the present time. After cooling, the phosphorus is found hardened. It is then broken with a hammer, and taken out, ground in a mill with water, passed through a sieve, and washed with sulphuret of carbon to dissolve the white phosphorus which has not been transformed.

Another method of separating the white phosphorus, consists in exposing the amorphous phosphorus to damp air, when the white phosphorus acidifies, and it is only necessary to wash with water to dissolve the acid.

The surest and most economical method of eliminating the white phosphorus is that fol-lowed by Mr. Coignet. It consists in submitting phosphorus to the action of a boiling solution of caustic soda, which attacks and dissolves the ordinary phosphorus, and forms a soluble hypophosphite, and disengages phos-phurctted hydrogen. The ebullition is then continued, and the alkaline solution changes until all fetid odor has disappeared. It is then well-washed with water until all the soda is removed.

After the operation, the amorphous phosphorus is dried, and used as we shall hereafter indicate in the preparation of matches.

Uses of The Two Varieties of Phosphorus

The principal uses of the two kinds of phosphorus consist in the manufacture of matches. For this purpose the annual consumption in France is about 72,000 pounds, while for all other uses the consumption is not more than 1,000 pounds.