Table of the Combinations of Phosphorous and Phosphoric Acids, with the Salifiable Bases, in the Order of Affinity.
| Names of the Bases. | Names of the Neutral Salts formed by | |
| Phosphorous Acid, | Phosphoric Acid. | |
| Phosphites of(B) | Phosphats of(C) | |
| Lime | lime | lime. |
| Barytes | barytes | barytes. |
| Magnesia | magnesia | magnesia. |
| Potash | potash | potash. |
| Soda | soda | soda. |
| Ammoniac | ammoniac | ammoniac. |
| Argill | argill | argill. |
| Oxyds of(A) | ||
| zinc | zinc | zinc. |
| iron | iron | iron. |
| manganese | manganese | manganese. |
| cobalt | cobalt | cobalt. |
| nickel | nickel | nickel. |
| lead | lead | lead. |
| tin | tin | tin. |
| copper | copper | copper. |
| bismuth | bismuth | bismuth. |
| antimony | antimony | antimony. |
| arsenic | arsenic | arsenic. |
| mercury | mercury | mercury. |
| silver | silver | silver. |
| gold | gold | gold. |
| platina | platina | platina. |
[Note A: The existence of metallic phosphites supposes that metals are susceptible of solution in phosphoric acid at different degrees of oxygenation, which is not yet ascertained.—A.]
[Note B: All the phosphites were unknown till lately, and consequently have not hitherto received names.—A.]
[Note C: The greater part of the phosphats were only discovered of late, and have not yet been named.—A.]
Sect. XVI.—Observations upon Phosphorous and Phosphoric Acids, and their Combinations.
Under the article Phosphorus, Part II. Sect. X. we have already given a history of the discovery of that singular substance, with some observations upon the mode of its existence in vegetable and animal bodies. The best method of obtaining this acid in a state of purity is by burning well purified phosphorus under bell-glasses, moistened on the inside with distilled water; during combustion it absorbs twice and a half its weight of oxygen; so that 100 parts of phosphoric acid is composed of 28-1/2 parts of phosphorus united to 71-1/2 parts of oxygen. This acid may be obtained concrete, in form of white flakes, which greedily attract the moisture of the air, by burning phosphorus in a dry glass over mercury.
To obtain phosphorous acid, which is phosphorus less oxygenated than in the state of phosphoric acid, the phosphorus must be burnt by a very slow spontaneous combustion over a glass-funnel leading into a crystal phial; after a few days, the phosphorus is found oxygenated, and the phosphorous acid, in proportion as it forms, has attracted moisture from the air, and dropped into the phial. The phosphorous acid is readily changed into phosphoric acid by exposure for a long time to the free air; it absorbs oxygen from the air, and becomes fully oxygenated.
As phosphorus has a sufficient affinity for oxygen to attract it from the nitric and muriatic acids, we may form phosphoric acid, by means of these acids, in a very simple and cheap manner. Fill a tubulated receiver, half full of concentrated nitric acid, and heat it gently, then throw in small pieces of phosphorus through the tube, these are dissolved with effervescence and red fumes of nitrous gas fly off; add phosphorus so long as it will dissolve, and then increase the fire under the retort to drive off the last particles of nitric acid; phosphoric acid, partly fluid and partly concrete, remains in the retort.