Tinctura Cardamomi Composita

The colouring of this tincture is cochineal, which per se is used as an indicator in volumetric analysis of acids and alkalies. With distilled water the tincture gives much paler mixtures than with tap-water, because the latter is invariably alkaline, therefore darkens the colouring-matter. Generally a little fat is precipitated from the tincture on dilution with water, especially in presence of acids or salts which are not alkaline. Ammonium carbonate discharges the red colour, as in the following:

In both cases the mixture becomes colourless, and a slight precipitate is formed, due to the ammonium carbonate.

There is insufficient tannin in tr. cardam. co. to precipitate alkaloid from aqueous mixtures sufficiently strong in alkaloidal salt, e.g.:

The precipitate in both is most voluminous when tap-water is used. With distilled water it is not so rapidly formed, the colouring-matter of the cardamoms and fat from tinctures also being in the precipitate. In the case of b the precipitate was traced to tannin in the cinnamon of tr. cardam. co.

Tinctura Cimicifugae with acid and water in mixture precipitates a hard lump- this is how resinoids are made. The precipitate is diffusible if half a drachm of glycerin is added to each ounce of acidulated water before the tincture is poured in.