ACTION OF LEAD SALTS 173 



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Vnguentum PlumU lodidi. Ointment of Lead Iodide. (B P ) 

 Employed externally to absorb glandular swellings. ' 



ACTIOBT OF LEAD SALTS. 



Exterml—SolMUe lead salts differ somewhat from 

 salts of the other heavy metals in being more astringent and 

 less irritant.. This happens because they form a denser pre- 

 cipitate with albumin of the tissues and of secretions. The 

 actate wHch is generally used is dissociated slowly in 

 solution in contact with the tissues. The metallic ion coag- 

 ulates albumin by forming a lead albuminate, so producing 

 a protective pellicle over raw surfaces; while the acid 

 constituent has little effect (lack of irritation). It thus 

 makes the tissues drier, denser and harder — and contracts 

 vessels — but has no action on the unbroken skin. 



ZnjferaaL— Soluble salts of lead in concentrated solution 

 — and at times insoluble salts — cause gastro-enteritis in 

 large doses. Lead salts are absorbed in medicinal doses 

 whether taken in a soluble or insoluble state. The chemical 

 form of the lead compound at the time of absorption is 

 unknown. Lead is deposited in the tissues, especially in the 

 liver and kidney, and is very slowly eliminated in the urine 

 and intestinal m.'ucus, bile, milk and saliva. Lead salts 

 have a marked astringent action- on the entire digestive 

 canal and diminish secretions accordingly. After absorption 

 lead salts have no remote astringent action. 



Toxicology.- — Poisoning not infrequently occurs in ani- 

 mals at pasture, from eating paint, sheet lead, or products of 

 lead works. The drinking water may be contaminated with 

 lead, especially from new pipes, or lead receptacles in which 

 water has been standing. Hard water is not affected by lead 

 pipes, since an insoluble crust of lead phosphate and sulph- 

 ate is deposited upon the interior of the pipes. There is an 

 acute and chronic form of poisoning. The first is caused by 

 single large doses of soluble lead salts, and is characterized 

 by gastro-enteritis and colic; rarely there are symptoms of 

 absorption, as convulsions, coma, paralysis and death. The 

 fjEces are sometimes colored black with lead sulphide; the 

 vomitus is white from lead chloride. Three groups of symp- 



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