[9] Opium is to be digested in cold water, and the solution filtered. Pure ammonia is to be added to this liquid so long as a precipitate is produced. Impure morphine is thus obtained, which may be purified by dissolving it in acetic acid, and digesting it with animal charcoal. The solution is again decomposed by ammonia. This precipitate is to be washed with distilled water, and dissolved in boiling alcohol, from which pure morphine will crystallise upon cooling. The acetate is formed by dissolving the morphine in dilute acetic acid, and evaporating the solution to dryness upon a sand bath. [10] I have borrowed some of these details from the “Formulaire pour la Préparation et l’Emploi de plusieurs Nouveaux Médicaments,” par F. Magendie, Septembre 1825.—Fifth edition. [11] In the praise which appears to be so justly due to the foreign chemists, the German philosophers should not be overlooked. We may refer the discovery of the prussic acid to the labours of Scheele, and that of morphine to Sertunner; from which last discovery, we may consider that the idea of insulating the most important principles of other vegetable medicines took its rise. [12] The establishment for filtering the water of the Seine is upon a grand scale, and admirably conducted. The water is passed through a very thick bed of charcoal and gravel. Many of the inhabitants use large filtering stones in their cisterns, for accomplishing the same object. [13] M. Laennec had the goodness to present me with a stethoscope constructed according to his last improvement. For the convenience of my professional brethren, I have directed an ingenious workman to imitate this stethoscope; and Mr. Garden, Chemist, No. 372, Oxford Street, has under taken to keep a constant supply of the instruments for sale. TRANSCRIBER’S NOTE Obvious typographical errors and punctuation errors have been corrected after careful comparison with other occurrences within the text and consultation of external sources. Some hyphens in words have been silently removed, some added, when a predominant preference was found in the original book. Except for those changes noted below, all misspellings in the text, and inconsistent or archaic usage, have been retained. p27-> ‘if it do have’ amended to ‘if it does have’ p37-> ‘or the plural’ amended to ‘or the pleural’ p57-> ‘in the same Jounal’ amended to ‘in the same Journal’ p73-> ‘to the epigastricregion’ amended to ‘to the epigastric region’ p93-> ‘the acetate of morphium’ amended to ‘the acetate of morphine’ p108-> the printed fraction ‘2/10’ is unclear, and may be ‘8/10’ or ‘9/10’ p119-> ‘genuine pnuemonia’ amended to ‘genuine pneumonia’