This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
There are several methods of extracting morphia from opium. The U. S. officinal process consists essentially in macerating opium in water to exhaustion, adding alcohol to the infusion, precipitating the morphia by solution of ammonia, and purifying the precipitate by solution in boiling alcohol, and filtration while hot through animal charcoal. On cooling, the alcohol deposits the morphia in crystals. The object in adding alcohol to the infusion is that it may retain the colouring matter when the morphia is precipitated, which it does to a considerable degree. Thus procured, morphia contains a proportion of narcotina, from which, if deemed advisable, it may be separated by the agency of ether, which dissolves the narcotina, and leaves the morphia pure. For the preparation of the sulphate or muriate, however, this is not necessary; as the narcotina remains in the mother waters, upon the crystallization of these salts. As the acetate is usually prepared by evaporating its solution to dryness, the narcotina will contaminate it, unless previously separated from the morphia.
Morphia is in small, shining, colourless crystals, which are without smell, of a bitter taste, scarcely soluble in cold water, slightly so in boiling water, also slightly in cold alcohol, but freely in that liquid when hot, and almost insoluble in ether. Chloroform, the fixed and volatile oils, and aqueous solutions of potassa and soda dissolve it, and solution of ammonia has the same effect, but in much less degree. When heated in the open air. morphia burns, leaving a carbonaceous residue, which is wholly dissipated if placed on red-hot iron. Morphia affects test-paper like the alkalies, and forms soluble salts with most of the acids.. When either the alkaloid, or one of its salts, is touched with strong nitric acid, it assumes a deep-red colour, which after a time changes to yellow. In the state of crystals, or in strong solution, both it and its salts are rendered blue by sesquichloride of iron. Ammonia, added to a mixture of solutions of chlorine, and of morphia or its salts, develops a dark-brown colour, which is removed by a further addition of chlorine. Precipitates are produced in solutions of the salts of morphia by the pure alkalies and their carbonates; but, when the alkali is added in great excess, the morphia is redissolved. Ammonia has the latter effect much less than potassa or soda. Astringent substances throw down from solutions of the salts of morphia a tannate of the alkaloid, which is soluble in acetic acid. Morphia consists of 1 equivalent of nitrogen, 35 of carbon, 20 of hydrogen, and 6 of oxygen, to which are added 2 equivalents of water in (be crystalline state.