Morphine and its sulfuric and hydrochloric acid salts are white compounds crystallizing in needles or prisms.

M1. Concentrated nitric acid dissolves morphine or its salts with a blood-red color which gradually passes into a yellow. The latter is not changed to a violet by addition of stannous chloride but is colored reddish-brown. Only a small amount of the acid should be used (difference from quinine).

M2. Concentrated sulfuric acid dissolves morphine to a colorless liquid. If to this a trace of nitric acid is added there is no change in color, but if it has stood 24 hours, or is heated to 100oC for half an hour, the nitric acid produces a red. A crystal of potassium permanganate added to the concentrated sulfuric acid solution should produce no violet or purple color.

M3. Fröhde's reagent gives a violet solution, gradually changing to brown, green, and yellow.

M4. A neutral solution of ferric chloride with morphine or solutions of its neutral salts gives a blue color. Only a small quantity of the ferric compound can be used, as an excess prevents the reaction. The color is destroyed by free acids and impurities may prevent its appearance. The ferric chloride, which ordinarily has an acid reaction, must be prepared by subliming the crystals in a hard-glass tube after driving off the water and acid by gentle heating; then dis-solve the sublimate in distilled water. The solution should be nearly or quite neutral. Impurities may prevent the forma-tion of the color. The correctness of the reagent must be proved by its ability to produce the blue with a specimen of pure morphine sulfate. Some ptomaines give a greenish color, but not a blue. None of the other vegetable alkaloids give this result.

M5. Morphine with half its weight of sugar gives a red color to a drop of concentrated sulfuric acid.

M6. Vanadium sulfate produces a reddish, then a violet color.