It is said that the presence of much morphia will interfere with the above test. But morphia, again, is not extracted completely by the ether-chloroform; and I have not found it to hinder the reaction if performed carefully.
Brucia in ordinary quantities, quinine, cinchonine, veratrine, and santonine do not interfere. In strychnia poisoning, morphia should always be sought for, as it is used as an antidote. If found, its interference may be obviated thus. Dissolve the supposed strychnia in water with a little acetic acid, add an equal volume of ether, and then ammonia in slight excess, and shake well. The strychnia will dissolve in the ether, the morphia will remain in the aqueous liquid. On evaporating the ether, the strychnia will be isolated.
4. Dr. Marshall Hall’s physiological test is very delicate. With some small animal—preferably a frog—proceed as mentioned in the introduction (p. 6). Tetanic spasms are caused. But other poisons, ptomaines, and even the mechanical injury, may produce irritation and perhaps convulsions, so that the test is dangerous, except as confirmatory or negative.
5. Bichromate of potash solution gives with strychnia, at once or on standing, a yellow precipitate, appearing under the microscope as rectangular plates and prisms. (See Guy and Ferrier’s Forensic Medicine, p. 567.)
6. A sublimate of strychnia touched with a drop of dilute picric acid solution, strength 1 in 250, gives microscopic arborescent crystallizations of peculiar curved forms. (Ibid.)
7. Treated with concentrated sulphuric acid and then with a crystal of sodium nitrite, strychnia gives a dirty yellow colour, changed by an alcoholic solution of potash to a fine orange-red, by an aqueous solution to brownish green, and finally to dirty red-brown. (Arnold, Arch. d. Pharm. 3, 20, 561.)
8. Mercuric chloride produces a white precipitate, as also does potassium sulphocyanide. All the general reagents for alkaloids precipitate strychnia. If, however, the reaction with sulphuric acid and manganese have come out properly, all the other tests are superfluous; if it has not been obtained, none of the other tests will be of use.
Preparations.
| Name. | Composition. | Approximate Amount of Strychnia. | Approximate Amount of Brucia. |
| Liquor Strychniæ, B.P. | Aqueous solution of strychnia hydrochloride | 4 grs. in 1 fl. oz. | None. |
| Tinct. Nucis Vom. | Nut extracted with spirit | 0·15 per cent. | 0·15 per cent. |
| Extractum Nuc. Vom., English Pharm., &c. | Spirituous extract evaporated | 3 to 4 per cent. | 3 to 4 per cent. |
| Extractum Nuc. Vom., Germ. Pharm. | Aqueous extract evaporated | ½ to 1 per cent. | 1½ to 3 per cent. |
| Extr. Fab. Ignatiæ, American. | From St. Ignatius’s bean | 5 per cent. | Very little. |
Vermin Killers.