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ELEMENTS OF MATERIA MEDICA.
Properties. —Cyanide of zinc is a white powder, insoluble in wateror alcohol.
Characters. —If a strong mineral acid be added to it, hydrocyanicacid is developed, and a soluble salt of zinc obtained. The latter isrecognized by the tests before mentioned for a solution of zinc (p. 522).
Composition. —Its composition is as follows :—
Eq. Eq. Wt. Per Cent.
Zinc. 1 . 32 . 55*2
Cyanogen. 1 . 26 44'8
Cyanide of Zinc . . 1 .58 1000
Physiological Effects. —Its effects have not been carefully ascer-tained, but they are supposed to be similar to those of hydrocyanic acid.
Uses. —It has been used principally in affections of the nervous system,as epilepsy, hysteria, and chorea. It has also been employed in car-(lialgia and cramps of the stomach, and as an anthelmintic in children.
Administration. —We may give it in doses of from a quarter of a grainto a grain and a half three times a day. It may be taken in the form ofpowder mixed with calcined magnesia.
Order 26.— Iron and its Compounds.
Fer'rum.—Trcn.
History. —This metal (called by the alchymists Mars ) was known inthe most ancient times. It was employed medicinally at a very earlyperiod, namely, above 3200 years ago. Indeed, it appears to have beenthe first mineral used internally; and a curious anecdote is given of itsintroduction into medicine. Mel am pus (a shepherd supposed to possesssupernatural powers) being appliedto by Iphicles, son of Philacus, for aremedy against impotence, slaughtered two bulls, the intestines of whichhe cut to pieces, in order to attract birds to an augury. Among theanimals which came to the feast was a vulture, from whom Melampuspretended to learn that his patient, when a boy, had stuck a knife wetwith the blood of some rams into a consecrated chestnut-tree, and thatthe bark had subsequently enveloped it. The vulture also indicated theremedy, namely, to procure the knife, scrape off the rust, and drink it inwine, for the space of ten days, by which time Iphicles would be lusty,and capable of begetting children. The advice thus given by Melampusis said to have been followed by the young prince with the most perfectsuccess! (Le Clerc, Hist, de la Medecine.)
Natural History. —Iron is met with in both kingdoms of nature.
(a.) In the inorganic kingdom. —Few minerals are free from iron. Itis found in the metallic state ( native iron), in combination with oxygen(. haematite, micaceous iron, brown iron stone, and magnetic iron ore), withsulphur ( iron pyrites, and magnetic pyrites), w r ith chlorine ( pyrosmalite ),with oxygen and an acid ( carbonate, phosphate, sulphate, arseniate,tungstate, tantalate, titaniate, chromate, oxalate, and silicate.)
( b.) In the organic kingdom. —It occurs in the ashes of most plants,and in the blood and some other parts of animals.
Extraction. —In Sweden , iron is extracted from magnetic iron ore andmicaceous iron: in England, principally from clay iron ore (carbonateof iron.)