Substances & Homeopatic Remedies

Phosphoricum acidum

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Phosphoricum acidum



Traditional name

orthophosphoric acid, metaphosphoric acid, white phosphoric acid.

German: Phosphorsäure

Used parts

 (a) Solution
     Drug strength 1/10 w/v
     Acidum Phosphoricum 118 g
     Purified Water in sufficient quantity.
     To make one thousand milliliters of the solution.


 Chemical symbol: H3PO4
     Mol. Wt.: 97.995
  Minerals; Inorganic; Column Five


Original proving

Hahnemann in Materia Medica Pura. He gives directions for its preparation and for its potentization up to the "trillion - fold dilution".

Description of the substance

 Any one of three chemical compounds made up of phosphorus , oxygen, and hydrogen. The most common, orthophosphoric acid, H 3 PO 4 , is usually simply called phosphoric acid. Two molecules of it are formed by adding three molecules of water, H 2 O, to one molecule of phosphorus pentoxide (phosphoric anhydride, P 2 O 5 ). It occurs as rhombic crystals or as a viscous liquid; both are deliquescent. The crystals melt at about 42. It has specific gravity 1.834 at 18, is soluble in alcohol, and is very soluble in water. It is a tribasic acid and forms orthophosphate salts with either one, two, or all three of the hydrogens replaced by some other positive ion. When it is heated to about 225, it dehydrates to form pyrophosphoric acid, H 4 P 2 O 7 ; at still higher temperatures metaphosphoric acid, HPO 3 , is formed. Salts of pyrophosphoric acid are pyrophosphates; salts of metaphosphoric acid are metaphosphates. Phosphoric acid is prepared commercially by heating calcium phosphate rock with sulfuric acid; purer grades may be prepared by treating red phosphorus with nitric acid. It is used in pickling and rust-proofing metals, in acidifying jellies and beverages, and in preparing phosphate salt.(4)

Phosphoric acid is a colorless, odorless liquid. It is a weaker acid than sulfuric acid, nitric acid or hydrochloric acid, and is relatively non-volatile and stable at elevated temperatures.

Phosphoric acid is manufactured either by the thermal or wet process. Phosphoric acid by the wet process has fluorine, organic compounds, and sulfate groups because the process cannot completely remove impurities. On the contrary, the thermal process can produce high quality products. (2)

Phosphoric acid is a mineral acid with the chemical formula H3PO4. Its main uses are in fertilizers and detergents, and in cleaning and rust-proofing agents. It is also used to acidify foods and beverages such ascola. It is prepared by adding sulphuric acid to calcium phosphate rock.

In its anhydrous form the acid is a white solid. In aqueous solution, the acid releases three hydronium (H+)ions.

The anion associated with phosphoric acid is called the phosphate ion, and is found pervasively in biology, especially in the compounds derived from phosphorylated sugars, such as DNA and RNA and adenosine triphosphate (e.g. ATP).(5)

Phosphoric acid can exist as a crystal or clear liquid. It is an oily, thick, colorless, and odorless liquid, or a thick, colorless, unstable crystalline solid.

Chemical properties:
Phosphoric acid is incompatible with strong caustics and most metals. It readily reacts with metals to form flammable hydrogen gas. The liquid can solidify at temperatures below 21 degrees C. It is corrosive to ferrous metals and alloys. It is soluble in alcohol and hot water. It can form three series of salts: primary phosphates, dibasic phosphates, and tribasic phosphates. It is deliquescent and hygroscopic. It is a chelating agent. It has a low vapor pressure at room temperature. (3)