QUALITIES. _Form_, a powder of a brownish green colour; _Odour_, none;
_Taste_, slightly styptic; it attracts humidity from the atmosphere, but
does not deliquesce. CHEMICAL COMPOSITION. Mr. Phillips has devoted much
attention to this subject, and he states that as it is frequently
prepared, it is a mere mixture of metallic iron with super-tartrate of
potass, coloured by oxide of iron; when however it is made with more
care, it appears to be a double salt, consisting of tartrate of potass
and tartrate of iron; or may it not be one of those combinations which
cream of tartar forms with metals, and of which I have spoken under the
article _Antimonium Tartarizatum_? The quantity of peroxide of iron
contained in any weight of this preparation may be seen by referring to
the _Medicinal Dynameter_; five grains, for instance, will be found to
contain gr. j of peroxide, which, it will be observed, are equivalent to
♏︎xiv of the _Tinctura Ferri Muriatis_, and to ♏︎xxv of the _Liquor
Ferri Alkalini_, or to f℥j of the _Vinum Ferri_. SOLUBILITY. It is very
soluble in water, and the solution remains for a great length of time
without undergoing any change, except that of depositing _tartrate of
lime_, which is an incidental impurity in the super-tartrate of potass.
INCOMPATIBLE SUBSTANCES. _All strong acids_; _lime water_;
_hydro-sulphuret of potass_; _astringent vegetables_? _The fixed
alkalies and their carbonates_ decompose the solution very slowly,
unless heated; but _ammonia_ and its _sub-carbonate_ produce upon it no
effect, whether it be hot or cold; this fact, observes Mr. Phillips,
will enable us to exhibit iron in solution with an alkali, without the
occurrence of an precipitate. FORMS OF EXHIBITION. The perfect
preparation, from its tendency to deliquesce, cannot be well ordered in
the form of powder; that of solution is probably the most judicious.
MED. USES. It is supposed to add to its chalybeate virtues those of a
diuretic nature. DOSE, grs. x to ʒss. See _Form: 34, 53, 92_. Dr.
Bateman has recommended a watery solution of it, as a chalybeate
peculiarly suited to children, from its tasteless quality.[510]