78 MATERIA MEDIC A AND THERAPEUTICS. 



of plasma and leucocytes, which characterises chronic inflam- 

 mation or catarrh, is checked. Solutions of the ferric salts are 

 therefore used as haamostatics to arrest hemorrhage from 

 accessible parts, such as leech-bites, the nose, and uterus ; less 

 extensively in chronic discharges from the vagina, rectum, and 

 nose, as astringents. Injected into the rectum, they destroy 

 worms. Iron is not absorbed by the unbroken skin. 



Internally. The constringent effect of iron is appreciated 

 in the mouth as a " styptic taste." Beyond this, the local 

 action corresponds with that just described externally. Various 

 iron solutions are usefully applied, either as gargles or with the 

 brush, in some forms of chronic sore throat. 



In the stomach all the salts of iron, whatever their nature, 

 are converted into the chloride, and do not combine with the 

 acid albuminates, like some of the other metals. Deficiency of 

 hydrochloric acid or of food, or excess of iron, thus decomposes 

 the gastric juice, and allows the iron to act upon the mucous 

 membrane as an astringent and irritant. Iron is thus directly 

 unfavourable to digestion ; and in this connection we must 

 carefully note (1) that iron may disorder the digestion even in 

 healthy subjects ; (2) that it must not be given for disease 

 until the gastric functions have been so far restored ; (3) that it 

 is well to begin then with the mildest preparations ; and (4) that 

 it must be given after meals. Iron is a valuable antidote in 

 arsenical poisoning, the humid peroxide (Fe 2 6HO) forming with 

 arsenious acid an almost insoluble compound (As 2 3 -j- 2(Fe 2 

 6HO) = Fe.jAs. 2 8 + Fe2HO + 5H 2 0). Abundance of the 

 iron should be given, and the compound should be quickly 

 expelled by a smart purge of sulphate of magnesia or soda. 

 The solutions of the persalts are used to arrest haemorrhage 

 from the stomach. In the duodenum iron is converted into an 

 alkaline albuminate, and thus absorbed. The further effect of 

 iron on the bowel is a remote one, to be presently described. 



2. ACTION ON THE BLOOD, AND ITS USES. 



The action of iron on the blood is almost unique of its kind: 

 first, because its specific action is exerted, not upon the plasma, 

 but upon the red corpuscle, and on this alone, not on any 

 other tissue or organ ; secondly, because this action appears to 

 be nothing more than the combination of the iron as one of the 

 constituent elements of the corpuscle with the others. In the 

 case of no other metal can we speak so definitely of its modus 

 operandi. 



Iron enters the circulation along the whole length of the 

 alimentary canal as the chloride and alkaline albuminate, and 

 quickly unites with the corpuscles, as it cannot be found in the 



