Preparation

This is obtained by first decomposing the phosphate of lime, contained in calcined bones, by means of dilute sulphuric arid, and afterwards decomposing the excess of phosphoric acid in the superphosphate thus procured, by heating the latter with charcoal, which takes the oxygen of the acid, and escapes as carbonic acid, while the phosphorus distils over, and is received under water, where it hardens.

Properties

As usually kept in the shops, phosphorus is in cylindrical sticks, of a light-yellowish colour, translucent, tasteless, of an odour like that of garlic, quite insoluble in water, very slightly soluble in alcohol, of which a fluidounce dissolves only about a grain,* and considerably more soluble in ether, chloroform, and the fixed and volatile oils. In the absence of air, it melts and is volatilized by heat. It is extremely inflammable, taking fire at 100° Fahr., or with slight friction at ordinary temperatures, and sometimes when held between the fingers without friction. Exposed to the air at common temperatures, it undergoes a slow combustion, emitting white fumes, which shine like flame in the dark. Hence, it must be kept under water; but, even thus protected, it appears to unite with the absorbed oxygen of the water, as it is asserted to impart active properties to the liquid. Phosphoric acid results from its rapid, phosphorous acid from its slower combustion. To the latter it no doubt owes its alliaceous smell.*

* M. Labarraque supposed (bat alcohol might dissolve a grain and a half to the ounce (Dict. de Mat. Med., .Merat et De Lens, v. 277); and Dr. Boling, of Montgomery, Alabama, found that an ounce would dissolve a grain, or possibly a little more.