[437]. Although the Camphor of commerce is generally furnished by the Laurus Camphora, yet it is abundantly yielded by many other plants. It is said that what is imported from Sumatra is the product of the Dryobobans Camphora. It is also contained in the roots of the Cinnamon, Cassia, and Sassafras laurels, and in those of Galangale, Zedoary, and Ginger; in Cardamom seeds and Long Pepper. The essential oils of Lavender, Sage, Thyme, Peppermint, Rosemary, and those of many other labiate plants yield camphor by distillation. Camphor may be also artificially formed by driving a stream of muriatic gas through oil of turpentine; this factitious product, however, is to be distinguished from native camphor in not being soluble in weak nitric acid, and also in not being precipitated by water from its solution in strong nitric acid.
[438]. The collection of the Materia Medica at the College of Physicians contains a beautiful specimen of native Camphor in the wood: having selected from it as perfect a crystal as I could find, I requested my friend and publisher Mr. W. Phillips, well known for his researches in crystallography, to undertake its examination; and he observes that “The crystal of native Camphor (in the wood) appears as a flat octohedron; but the primary form is a right rhombic prism of 51° 36′ and 128° 24′. by measurement with the reflective goniometer on cleavage planes: the octohedral appearance arises from the deep replacement of four of the solid angles of the prism, by as many planes.”
[439]. An Odontalgic Remedy in great repute consists of a solution of camphor in oil of turpentine; a fluid-ounce of which will dissolve two drachms.
[440]. Although the London College, for reasons sufficiently weighty, were induced on a former occasion to transfer the Blistering fly from the genus Cantharis to that of Lytta, the Committee for revising the late Pharmacopœia determined, on the authority of Latreille, to restore it to its former genus. The work of Latreille, “Genera Crustaceorum et Insectorum” holds the highest rank in Entomology of any hitherto published.
[441]. Cantharidin may be obtained by the following process: Boil the cantharides in water until all the soluble parts are extracted; filter the decoction, and evaporate to the consistence of an extract. Digest this extract in concentrated alcohol, then pour off the alcohol and evaporate it; if sulphuric acid be then added to this extract, it will take up the Cantharidin, which may be obtained in a tolerably pure state by evaporation. The crystalline plates may be afterwards freed from the adhering colouring matter by alcohol.
[442]. Annales de Chémie, tom. lxxvi.
[443]. It forms the basis of the once celebrated diuretic of Tulpius, called Lithonthrypticum Tulpii, from its supposed efficacy in stone. The other ingredients were Cardamoms, made into a Tincture with Rectified Spirit, and Spirit of Nitric Æther.
[444]. He was cited before the censors of the College of Physicians in 1693, and committed to Newgate by a warrant from the President; but he was acquitted upon the plea that—bad practice must be accompanied with a bad intention to render it criminal. He published his vindication in a small tract, entitled “De tuto Cantharidum usu interno.” The issue, says Dr. Quincey (Pharm: p. 152) ruined the unhappy Doctor, but taught his prosecutors the safety and value of his practice. The following was his formula. Of egg-shells calcined ʒss; Camphor ℈j; Spanish flies ℈ss; and Venice turpentine q, s, to make nine pills; three of which were to be swallowed every three hours.
[445]. Not less than sixteen species of the genus Cantharis have already been discovered in this country, by the industry of our Entomologists; most, if not all, of which possess vesicating powers. Of these the most common is the Lytta vittata, or potatoe fly. The medicinal virtues of this insect were first discovered in 1797, and found to be fully equal to those of the Spanish fly. Dr. Barton says “from frequent employment of the two articles, I cannot hesitate to prefer the American to the foreign fly. Long keeping, provided it be carefully kept, does not materially impair the blistering property of the Lytta vittata. At the end of three or four years after being collected, I have found it equal in power to the shop Cantharides.” By the late Dr. Dana, Prof. of Chemistry in the College of Physicians and Surgeons of New-York, the Lytta vittata was made the subject of analysis, and found to contain Cantharidin. Ed.
[446]. Journal de Physique, p. 173, 1820.