GENERAL ACTIOjST OF IEOjST AND ITS SALTS 199 



irritant and astringent salts, as the perchloride, may induce 

 gastroenteritis by local irritation. 



Internally in the stomach the iron salts behave as they 

 do externally. Acid ions are set free from the iron salt and 

 the metal combines with albumin. The liberation of the acid 

 ion leads to an astringent action and, if large doses are in- 

 gested, actual irritation. The degree of astringency is due 

 to the preparation also. Thus ferric chloride is especially 

 astringent because of the ease of dissociation and corrosive 

 action of the HCl ion. Ferrous sulphate is only a little less 

 so; while reduced iron, the oxide, carbonate, double salts 

 and salts of the vegetable acids (citrates, acetates and tar- 

 trates), and albuminates, are very slightly or not at all as- 

 tringent. In the case of the salts of the organic acids and 

 double salts the acid ions are but slowly dissociated, and in 

 that of the albuminate there is no acid to be freed. Acid 

 salts, as the sulphate, are more suitable for the horse than the 

 dog. Iron may blacken the tongue from formation of the 

 sulphide. In the stomach all forms of iron are converted 

 into chlorides, by the HCl of the gastric juice, and then 

 probably into albuminates. 



Iron is naturally absorbed from the organic compounds 

 of the metal existing in the nucleoalbumins of food,^ and, 

 either existing in this form or when given in medicine in the 

 inorganic state, it is probably absorbed chiefly from the duo- 

 denum as the albuminate. But in any event the greater por- 

 tion escapes from the bowel unabsorbed. The route which 

 iron follows, after absorption, has been quite accurately as- 

 certained by many experiments. It is taken up from the 

 duodenum by the epithelial cells and leucocytes and carried 

 by the blood into the spleen, in M'hich it is first deposited. 

 From thence, through the blood, it is conveyed to the liver 

 and bone marrow. If it is needed for blood making it is 

 transformed by many steps into hemoglobin in the liver. But 

 if it is not so needed it is eliminated by the large intestme 

 and escapes from the bowel in the form of the sulphide and 

 albuminate — the feces turning dark on exposure to air. 



Constitutional Action.— This is not observed imless 

 iron is given intravenously. A salt which will not coagulate 



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