PYROPHORUS

, the name usually given to that substance by some called black phosphorus; being a chemical preparation possessing the singular property of kindling spontaneously when exposed to the air; which was accidentally discovered by M. Homberg, who prepared it of alum and human fæces. Though it has since been found, by the son of M. Lemeri, that the fæces are not necessary to it, but that honey, sugar, flour, and any animal or vegetable matter, may be used instead of the fæces; and M. De Suvigny has shewn that most vitriolic salts may be substituted for the alum. See Priestley's Observ. on Air, vol. 3, Append. p. 386, and vol. 4, Append. p. 479.