Tests. 1. Potassium hydrate and ammonia precipitate morphia from solution of its salts, under the form of a white crystalline powder, which is very soluble in excess of hydrate of potassium, and, with somewhat more difficulty, in excess of ammonia. The solution formed by excess of the first is precipitated on the addition of bicarbonate of potassium. The precipitate in either case is soluble in a solution of chloride of ammonium, and in dilute acetic acid, and is insoluble in ether. A careful inspection of the precipitate through a lens of small power shows it to consist of minute acicular crystals; and seen through a glass which magnifies 100 times, these crystals present the form of right rhombic prisms.—2. The carbonates of potassium and sodium produce the same precipitate as hydrate of potassium, and which is insoluble in excess of the precipitant.—3. The bicarbonates of potassium and sodium also give similar precipitates from neutral solutions, insoluble in excess. In each of the above cases stirring with a glass rod and friction on the sides of the vessel promote the separation of the precipitate.—4. If to a mixture of morphia and oil of vitriol a minute fragment of bichromate of potassium be added, oxide of chromium is set free, and a fine green colour developed.—5. A drop or two of solution of terchloride of gold added to a weak solution of morphia gives a yellow precipitate,
which is mostly redissolved on agitating the liquid, which then assumes various hues (green, blue, violet, purple) on the addition of a drop of liquor of potassa.—6. A minute fragment of terchloride of gold and of hydrate of potassium very gently dropped into the liquid, occasion purple clouds or streaks in dilute solutions, followed by a precipitate, which is violet, purple, or blue-black, according to the strength of the liquid.
Another test, given by Siebold,[41] is the following:—“Heat the substance which is believed to be, or to contain, morphia, gently with a few drops of sulphuric acid, add a very small quantity of pure perchlorate of potassium. The liquid immediately surrounding the perchlorate will at once assume a deep brown colour, which will soon spread and extend over the greater part of the acid. Warming increases the delicacy of the test. 0·0001 gramme of morphia can be distinctly recognised in this way, and no other alkaloid is acted upon in a similar way by the substances named. It is indispensable, however, for the success of the experiment that the perchlorate of potassium be absolutely free from chlorate.” See Alkaloids.
[41] ‘Year Book of Pharmacy,’ 1873.
The above are the most reliable precipitates for morphia; the first two may, indeed, be regarded as characteristic, and the remainder as almost so. The following are often referred to by medical writers, but are less exclusive and trustworthy:—Morphia and its salts are—7. Reddened by nitric acid, and form orange-red solutions, darkened by ammonia in excess, and ultimately turning yellow, with the production of oxalic acid.—8. They are turned blue by ferric chloride, either at once or on the addition of an alkali, and this colour is destroyed by water and by alkalies, or acids in excess.—9. Iodic acid added to their solutions turns them yellowish brown, by setting iodine free, and the liquid forms a blue compound with starch.
Uses. Morphia and its salts are exhibited either in substance, made into pills, or in solution, generally the latter; or externally, in fine powder, applied to the dermis denuded of the cuticle. They are principally employed as anodynes and hypnotics in cases in which opium is inadmissible, and are justly regarded as the most valuable medicines of their class. “In cases wherein both opium and the morphine salts are equally admissible, I prefer the former, its effects being better known and regulated; moreover, opium is to be preferred as a stimulant and sudorific, and for suppressing excessive mucous discharges.” (Pereira.)—Dose. Of pure morphia, 1⁄12 to 1⁄6 gr.; of its salts, 1⁄8 to 1⁄4 gr.; externally, 1⁄2 to 11⁄2 gr. Morphine is chiefly used for the preparation of the acetate, and some of its other salts.
Good opium yields from 10% to 13% of morphia. See Opium.
Morphia, Ac′etate of. C17H20NO3C2H3O2. Syn. Morphiæ acetas (Ph. L., E., & D.), L. Prep. 1. (Ph. L. 1836.) Morphia, 6 dr.; acetic acid (Ph. L.), 3 fl. dr.; distilled water, 4 fl. oz.; dissolve, gently evaporate, and crystallise.
2. (Ph. E.) Hydrochlorate of morphia, 1 part, is dissolved in warm water, 14 parts; and the solution, when cold, is precipitated with ammonia, in slight excess, the precipitate is washed in cold water, and dissolved by means of acetic acid, in excess, in warm water, 12 parts; from the solution crystals are obtained as before.
3. (Ph. D.) Morphia (in fine powder), 1 oz.; rectified spirit, 8 fl. oz.; mix, apply a gentle heat, and add of acetic acid (sp. gr. 1·044), 41⁄2 fl. dr. or q. s., until a neutral or slightly acid solution is obtained; evaporate this to the consistence of a syrup by steam or water heat, and set aside the residuum for a few days until it solidifies.