eat; carbonic acid is formed, and escapes in the state of gas;
the sulphur remains combined with the clay, lime, &c. in the state of
sulphuret, which is decomposed by acids; the acid unites with the earth
into a neutral salt, and the sulphur is precipitated.

TABLE _of the Binary Combinations of Phosphorus with the Simple
Substances._

_Simple Substances._ _Resulting Compounds._

Caloric Phosphoric gas.

{ Oxyd of phosphorus.
Oxygen { Phosphorous acid.
{ Phosphoric acid.

Hydrogen Phosphuret of hydrogen.
Azote Phosphuret of azote.
Sulphur Phosphuret of Sulphur.
Charcoal Phosphuret of charcoal.
Metallic substances Phosphuret of metals(A).

Potash }
Soda }
Ammoniac } Phosphuret of Potash,
Lime } Soda, &c.(B)
Barytes }
Magnesia }
Argill }

[Note A: Of all these combinations of phosphorus with metals, that with
iron only is hitherto known, forming the substance formerly called
Siderite; neither is it yet ascertained whether, in this combination,
the phosphorus be oxygenated or not.--A.]

[Note B: These combinations of phosphorus with the alkalies and earths
are not yet known; and, from the experiments of Mr Gengembre, they
appear to be impossible--A.]

SECT. IX.--_Observations upon Phosphorus, and its Combinations._

Phosphorus is a simple combustible substance, which was unknown to
chemists till 1667, when it was discovered by Brandt, who kept the
process secret; soon after Kunkel found out Brandt's method of
preparation, and made it public. It has been ever since known by the
name of Kunkel's phosphorus. It was for a long time procured only from
urine; and, though Homberg gave an account of the process in the Memoirs
of the Academy for 1692, all the philosophers of Europe were supplied
with it from England. It was first made in France in 1737, before a
committee of the Academy at the Royal Garden. At present it is procured
in a more commodious and more oeconomical manner from animal bones,
which are real calcareous phosphats, according to the process of Messrs
Gahn, Scheele, Rouelle, &c. The bones of adult animals being calcined to
whiteness, are pounded, and passed through a fine silk sieve; pour upon
the fine powder a quantity of dilute sulphuric acid, less than is
sufficient for dissolving the whole. This acid unites with the