Iron. A metal which, in its metallic state, is probably inert, or only acts mechanically; but it readily oxidizes in the alimentary canal, and thereby acquires medicinal power. It is one of the few metals which, by oxidizement, is not rendered more or less poisonous. (Pereira.) Its chief medicinal use is as the basis of the following preparations.

1136. The Modus Operandi of the Salts of Iron is almost entirely through and upon the blood, which it improves by increasing the quantity, and improving the quality of the blood-corpuscles. Andral details a case of Chlorosis, in which the blood was examined, and the proportion of globules was only 49. Iron was administered for some time, and the proportion rose to 64. In another case, the proportion, under the use of Iron, rose from 46 to 95. Simon* also gives the case of a Chlorotic girl, in whom the blood contained Globulin 60, And Hamiatin 1 431. Iron was administered for seven Weeks; at the end of that period, the blood contained Globulin 90.810, HAematin 4.598. He observes that the changes in the condition of the patient kept pace with that of the blood. She was before pale, her lips and cheeks were colourless, but now she presented a really blooming appearance. Pereira has given the name hmatinic to the preparations of iron, on account of the property they possess of augmenting the amount of hAematin in the blood. To this property of enriching the blood may be ascribed its efficacy in preventing the development of tubercular disease. M. Coster's observations on this point are highly interesting. He placed a number of dogs, rabbits, &c., in the circumstances generally supposed to be the most favourable to the development of scrofula and tubercular disease; namely, cold damp cellars, without light; they were prevented from moving, and exposed to a most unwholesome atmosphere. Some of the animals were fed upon ordinary food; others upon bread, containing half an ounce of the Sesquioxide of Iron in each lb. j. of bread. The former, with one or two exceptions, became tuberculous; whilst not one fed upon the ferruginous bread presented even a trace of tubercles, When taken internally, the Salts of Iron are absorbed into the system, and have been detected in the blood, the urine, and the milk; a portion of them passes off by the bowels, as is evidenced by the black fAeees which are always observed after a few doses of any of the stronger Salts of Iron. Under their use, the digestion is improved, the appetite becomes greater, the pulse increases in frequency and fulness, and the general healthimprovs: the patient at the same time gams flesh and colour. Those effects are often very marked. From some recent observations by Dr. Pokrowsky. made in the Hospital at St. Petersburg, it appears that under the use of Iron, the temperature of the body, whether previously normal or morbidly depressed, rises, and the daily amount of urea excreted in the urine is increased. The weight of the body also is augmented. These effects were produced alike by all the preparations of Iron In some persons, the Salts of Iron cause great gastric irritation. In excessive doses, they are irritant poisons.