This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
An alkaloid prepared from opium.
Characters. - Colourless or white shining prismatic crystals, or a crystalline powder. Permanent in air, having a bitter taste and alkaline reaction. Heated on platinum foil, the crystals fuse, char, and disappear.
Solubility. - Slight in cold water; complete in 500 parts boiling water; in 100 alcohol at 15° C. (59° F.); in 36 boiling alcohol; in 13 boiling absolute alcohol; almost insoluble in ether; slightly soluble in chloroform.
Reactions. - Morphine is first reddened and then rendered yellow by nitric acid. With ferric chloride it gives a blue colour, changed to green by excess of the reagent, and destroyed by free acids or alcohol, but not by alkalis. A solution of morphine, acidified by acetic or sulphuric acid, is not precipitated by tannic acid.
Impurities. - Other alkaloids.
Tests. - On adding 20 parts of colourless solution of soda or potassa to 1 part of morphine, a clear, colourless solution should result without a residue (absence of other alkaloids). Morphine yields a colourless solution with cold concentrated sulphuric acid, which should not acquire more than a reddish tint by standing for some time, and which should not assume a purple or violet, but merely a greenish colour, on the addition of a small crystal of bichromate of potassium (absence of and difference from strychnine, brucine, &c).