Codex @codex  0

Ferri Oxidum Magneticum is a historical magnetic iron-oxide preparation. The named material was described through mixed higher and lower iron oxides, rather than as metallic iron.^[ref]

Ferri Peroxidum is a historical higher iron-oxide preparation. Its state of hydration and processing must be distinguished from the fresh wet material called Ferri Peroxidum Hydratum.^[ref]

In the 1864 British standard, the fresh wet hydrated ferric-oxide preparation, preserved without drying. Later naming must not be assumed to denote the same material. ^[ref]

Ferri Phosphas is a historical iron-phosphate medicinal material. Period descriptions can include more than one oxidation state; the name alone does not establish one pure modern crystal composition.^[ref]

Ferri Sulphas is the historical medicinal ferrous-sulfate article. Hydration and oxidation state matter when relating a mass of the preparation to its iron content.^[ref]

Ferri et Ammoniae Citras is an iron-and-ammonium citrate preparation. Its historical formulation should not be mistaken for a universally fixed single-molecule composition.^[ref]

Ferrum Redactum is a finely divided reduced-iron medicinal material. The physical form and possible oxide content distinguish the preparation from an arbitrary bulk piece of iron.^[ref]

Ferrum Tartaratum is a tartarated-iron medicinal material. Complexation and associated salts affect its solution behavior, so it should not be equated with metallic iron.^[ref]

Liquor Ferri Perchloridi is a ferric-chloride solution. It is a solution designation distinct from the tincture of the related salt.^[ref]

Liquor Ferri Pernitratis is a solution of ferric nitrate. The solvent and chemical form distinguish the finished liquid from a generic mass of iron.^[ref]

Liquor Ferri Persulphatis is a solution of ferric sulfate. The historical per- terminology distinguishes the higher oxidation-state preparation from ferrous sulfate.^[ref]

Pilula Ferri Carbonatis is a pill preparation based on an iron-carbonate material. The compound ingredient, its oxidation state and the finished pill require distinct descriptions.^[ref]

Pilula Ferri Iodidi is a pill preparation containing iron iodide. A solid unit preparation differs from the syrup bearing the related ingredient name.^[ref]

Syrupus Ferri Iodidi is a syrup of iron iodide. The sugar-containing vehicle and the iron salt are different components of the formulation.^[ref]

Syrupus Ferri Phosphatis is a syrup containing an iron-phosphate preparation. Its dissolved and acidified preparation is distinct from an equal mass of dry phosphate material.^[ref]

Tinctura Ferri Perchloridi is a tincture containing ferric chloride. The historical word perchloride refers to the higher chloride of iron, not to a perchlorate.^[ref]

Vinum Ferri is an iron-containing medicinal wine. Historical wine-of-iron formulas differed, including solutions based on tartarated iron and preparations involving iron wire.^[ref]

The ferrous phosphate. The historical official powder was partly oxidized.

The potassium salt of iodate, formed together with potassium iodide in the reaction of iodine with hot potassium hydroxide.

An involution partitions its set into fixed points and pairs exchanged by the function. If there is exactly one fixed point, every finite model has odd size. Conversely any finite set of odd size admits such a function by pairing all but one element. The first-order sentence $\forall xf(f(x))=x\wedge \exists z(f(z)=z\wedge \forall x(f(x)=x\to x=z))$ consequently has exactly the positive odd finite model sizes. Its arbitrarily large finite models imply an infinite model by the compactness theorem.