558 PHOSPHORUS 



in a state of bright ignition. After 3 or 4 hours of steady firing, carbonic acid and 

 sulphurous acid gases are evolved in considerable abundance, provided the materials 

 had not been well dried in the iron pot ; then sulphuretted hydrogen makes its appear- 

 ance, and next phosphuretted hydrogen, which last should continue during the \vhole 

 of the distillation. 



The firing should bo regulated by the escape of this remarkable gas, which ought 

 to be at the rate of about 2 bubbles per second. If the discharge comes to be inter- 

 rupted, it is to be ascribed either to the temperature being too low, or to the retort 

 getting cracked ; and if upon raising the heat sufficiently no bubbles appear, it is a 

 proof that the apparatus has become defective, and that it is needless to continue the 

 operation. In fact, the great nicety in distilling phosphorus lies in the management 

 of the fire, which must bo incessantly watdied, and fed by the successive introduction 

 of fuel, consisting of coke with a mixture of dry wood and coal. 



We may infer that the process approaches its conclusion by the increasing slowness 

 with which gas is disengaged under a powerful heat; and when it ceases to como 

 over, wo may cease firing, taking care to prevent reflux of water into the retort, from 

 condensation of its gaseous contents, by admitting air into it through a recurved glass 

 tube or through the lute of the copper adapter. 



The usual period of the operation upon the great scale is from 24 to 30 hours. Its 

 theory is very obvious. The charcoal at an elevated temperature disoxygenates the 

 phosphoric acid with the production of carbonic acid gas at first, and afterwards car- 

 bonic oxide gas, along with sulphuretted, carburetted, and phosphuretted hydrogen, 

 from the reaction of the water present in the charcoal upon the other ingredients. 



The phosphorus falls down in drops, like melted wax, and concretes at the bottom 

 of the water in the receiver. It requires to be purified by squeezing in a shamoy 

 leather bag, while immersed tinder the surface of -warm water, contained in an earthen 

 pan. Each bag must be firmly tied into a ball form, of the size of the fist, and com- 

 pressed under the water heated to 130, by a pair of flat wooden pincers, like those 

 with which oranges are squeezed. 



The purified phosphorus is moulded for sale into little cylinders, by melting it at the 

 bottom of a deep jar filled with water, then plunging the wider end of a slightly tapering 

 but straight glass tube into the water, sucking this up to the top of the glass, so as to 

 warm it, next immersing the end in the liquid phosphorus, and sucking it up to any 

 desired height. 



The tube being now shut at bottom by the application of the point of the left 

 index, may be taken from the mouth and transferred into a pan of cold water to con- 

 geal the phosphorus ; which then will commonly fall out of itself, if the tube be nicely 

 tapered, or may at any rate be pushed out with a stiff wire. Were the glass tube not 

 duly warmed before sucking up the phosphorus, this would be apt to congeal at the 

 sides before the middle be filled, and thus form hollow cylinders, very troublesome 

 and even dangerous to the makers of phosphoric match-bottles. The moulded sticks 

 of phosphorus are finally to be cut with scissors under water to the requisite lengths, 

 and put up in phials of a proper size; which should be filled up with water, closed 

 with ground stoppers, and kept in a dark place. For carriage to a distance, each 

 vial should be wrapped in paper, and fitted into a tin-plate case. 



Phosphorus has a pale yellow colour, is nearly transparent, brittle when cold, soft 

 and pliable, like wax, at the temperature of 70 F., crystallising in rhombo-dodecahe- 

 drons out of its combination with sulphur, and of specific gravity 1'77. It exhales 

 white fumes in the air, which have a garlic smell, appear luminous in the dark, and 

 spontaneously condense into liquid phosphorus acid. Phosphorus melts in close vessels, 

 at 95 F 1 ., into an oily-looking colourless fluid; begins to evaporate at 217'5, boils at 

 554, and if poured in the liquid state into ice-cold water, it becomes black, but re- 

 sumes its former colour when again melted and slowly cooled. It has an acrid dis- 

 agreeable taste, and acts deleteriously in the stomach, though it has been administered 

 as a medicine by some of the poison-doctors of the present day. It takes fire in the 

 open air at the temperature of 165, but at a lower degree if partially oxidised, and 

 burns with great vehemence and splendour. 



PHOSPHORUS, AMORPHOUS, or RED PHOSPHORUS. If a stick of 

 phosphorus be put into an hermetically-closed tube and exposed to the action of tho 

 spectrum, one end will become white, and the other red. It may be prepared also by 

 exposing phosphorus for a long time in an atmosphere quite free of oxygen or moisture, 

 to a temperature of 470 F. At this temperature the phosphorus fuses ; it remains for 

 some time colourless, and then gradually becomes red and opaque. Amorphous 

 phosphorus was investigated by Dr. Schrotter, of Vienna. The apparatus for making 

 it consists of a double iron pan ; the intermediate space between the two contains a 

 metallic bath of an alloy of tin and lead; with a cast-iron cover to the inner vessel, 

 fitted to the top end by means of a screw, and fastened to tho outer vessel by screw- 



