"Take of sliced opium, one pound; of crystals of chloride of lead, two ounces, or a sufficient quantity; of purified animal charcoal, three ounces and a half; of hydrochloric acid, distilled water, solution of ammonia, each as much as may be requisite : macerate the opium in four pints of distilled water for thirty hours, and bruise it; then digest for twenty-four hours, and press. Macerate what remains again, and a third time, in water, that it may become tasteless, and each time bruise and press. Evaporate the mixed solutions, at a heat of 140°, to the consistence of syrup. Then add three pints of distilled water; and when all the faeces have subsided, decant the supernatant fluid. Add to this, gradually, two ounces of chloride of lead, or as much as may be sufficient, first dissolving it in four pints of boiling distilled water until nothing more is precipitated. Decant the fluid, and wash the residue frequently with distilled water. Then evaporate the mixed liquors as before, with a gentle heat, that crystals may be formed. Press these in a cloth, then dissolve them in a pint of distilled water, and digest with an ounce and a half of animal charcoal, at a heat of 120°, and strain.

Finally, the charcoal being washed, evaporate the fluids carefully, that pure crystals may be obtained. Mix the decanted fluid, from -which the first crystals have been formed, with a pint of water, and gradually drop in as much solution of ammonia, frequently shaking it, as may be sufficient to separate all the morphia. To this, washed, add distilled water acidulated with hydrochloric acid, that it may be saturated; then digest with two ounces of animal charcoal, and strain. Lastly, evaporate carefully the washing from animal charcoal and other fluids, that pure crystals may be obtained."

In this complex process, the meconate of morphia contained in the opium is decomposed by the chloride, of lead: at the same time a portion of the water is also decomposed, in order to furnish hydrogen to the chlorine to change it into hydrochloric acid, and oxygen to the lead to form it into a protoxide: the former unites with the morphia to form the hydrochlorate of morphia; and the latter with the freed meconic acid to form a meconate of oxide of lead, which, being insoluble, is precipitated. As opium contains a small proportion of a sulphate, a little sulphate of lead is also precipated with the meconate. The intention of the precipitation with ammonia, and the subsequent addition of the diluted hydrochloric acid, is to get the whole of the morphia: that of the addition of the animal charcoal, is to decolorize the salt.

The process which I have proposed, is, in my opinion, much simpler, and capable of obtaining a larger quantity of the hydrochlorate from a given quantity of opium. It consists in rubbing the opium in a hard, dry state, into a powder with clean sand, putting the whole into a percolator,1 with a piece of clean rag tied over the lower opening, and passing cold distilled water through until it acquires no taste. This solution is to be evaporated to the consistence of syrup, and then thrown into four times the quantity of distilled water, and the faeces allowed to subside. The fluid is to be decanted, and the residue well washed with distilled water. To the separated fluids a saturated solution of chloride of barium is next to be added, until no more precipitate is thrown down; and the insoluble meconate of baryta, thus formed, is to be separated by the filter, and well washed upon it. The fluid is now to be evaporated by a gentle heat to form crystals, which are to be pressed, redissolved in water, and digested with pure animal charcoal at a temperature of 120°, and strained. The strained fluid and the washings of the charcoal are to be submitted to cautious evaporation, to form crystals.

The residual fluid, which is viscid, from the pressure of the first crystals, being evaporated nearly to dryness, is to be largely diluted, and treated as before, to obtain any hydrochlorate of morphia which it may hold in solution.

1 For the description and a figure of this instrument, see Part i.

I have procured a much larger proportion of hydrochlorate of morphia by this process than by that of the Pharmacopoeia.

Qualities. - Hydrochlorate of morphia crystallizes in tufts of acicular crystals, which are anhydrous, nearly colourless, inodorous, and bitter; scarcely soluble in alcohol, but readily-soluble in 20 parts of water at 60°, and in 10 parts at 212°. They consist of one eq. of morphia = 288.23 +1 of hydrochloric acid = 36.42, making the equiv. = 304.65, or 88.48 parts of morphia +11.58 of acid, in 100 parts. The solution of this hydrochlorate is decomposed by the alkalies, ammonia, nitrate of silver, and the salts of lead; consequently it is incompatible in prescriptions with them.

Medical properties and uses. - The hydrochlorate of morphia is employed as a narcotic, and is preferred to the acetate, on account of its more definite strength, and owing to its exciting less perspiration. It is also much less subject to decomposition than the acetate. It dose is from gr. 1/4 to gr. 1/2, in any bland fluid.

Preparations of Potassa.