GENERAL ACTIONS 313 



in the gaseous, fluid, or solid state. One part in 4125 parts 

 of water arrests the action of diastase and ptyalin ; one part 

 in 7817 arrests the action of pepsin ; one part in 7000 

 destroys both bacilli and their spores (Wernitz and Koch). 

 Iodine stains the skin yellow-brown, and is almost the only 

 substance that penetrates the unbroken skin ; after local 

 application traces can always be found in the urine ; strong 

 solutions cause hypersemia, irritation, and desquamation 

 of the cuticle ; but the irritant action can readily be regu- 

 lated. The skin and nutritive processes may be stimulated ; 

 absorption of inflammatory products is assisted, and the 

 congestion and pain in some distal part may be relieved. 

 (See Counter-irritants.) A gradual and fairly prolonged 

 effect is produced when iodine is brought into contact with 

 either skin or mucous surfaces ; for it is volatile, slowly 

 penetrating, and so active for considerable periods on parts 

 with which it is placed in contact. Large doses if swallowed 

 cause gastro-enteritis, and if inhaled produce rhinitis, 

 laryngitis, and bronchitis. In the stomach it is converted 

 into iodides and iodates ; and it differs from the action of 

 iodides only in the fact that it is more irritant in the stomach. 

 Medicinal doses are absorbed, stimulate glandular activity, 

 and promote metabolism. In the tissues iodine may again 

 be set free, and combine with serum albumin, but iodine 

 albuminates are unstable, and hence readily removed. This 

 appears to explain the action of iodine and its compounds 

 in the liquefaction and absorption of pathological products. 

 It combines with lead, mercury, or other metals present in 

 the body, and hastens their removal. It is excreted by 

 the mucous surfaces and glands, notably in the saliva, 

 perspiration, bronchial secretion, milk, and urine, while full 

 doses during excretion irritate the excreting channels. 



Although the element itself is less active than chlorine or 

 bromine, its compounds are more active, probably because 

 they are more readily decomposed. The iodides of potas- 

 sium, sodium, and ammonium chiefly produce the effects 

 of the iodine, but are less irritant, less active as thyroid 

 gland stimulants, although more prone to affect the kidneys 

 than the element itself. The iodides of iron, copper, lead, 

 and mercury exhibit in addition the actions of their power- 



