The salts of barium are irritant with a special action on the nervous system shown by weakened action of the heart and spasms or paresis of the muscles. The chloride is used in staining wool, the nitrate and chlorate in producing green colors in fireworks, the oxide and carbonate in glassmaking, the chromate by painters, and the sulphate for giving weight and body to various white powders. The chloride is now largely used to stimulate intestinal peristalsis in animals. _Symptoms._ Barium chloride hypodermically produces tonic and clonic convulsions, increased peristalsis, discharges of urine and fæces, great restlessness, muscular prostration, emesis in vomiting animals, hurried, shallow respiration, weak, thready pulse, asthenia, coma, and death. _Lesions._ There is congestion of the gastric and intestinal mucosa, but this is rarely violent, and corrosion and ulceration are almost unknown. The agent indeed seems to act more energetically upon the nervous system than on the mucosa of the alimentary tract. _Treatment._ This consists in giving an alkaline sulphate (sulphate of soda, potash, or magnesia), to precipitate the insoluble barium sulphate, with anodynes (opium) and mucilaginous agents. POISONING BY IRON. Sulphate and chloride on empty stomach poisonous. Symptoms: Colic, emesis, rumbling, purging. Treatment: Alkaline or earthy carbonates, tannic acid, albumen. Opium. Sulphate and chloride are the principal poisonous compounds. Both are comparatively harmless even in large doses taken on a full stomach, while on an empty stomach they may cause violent gastro-enteritis. _Symptoms._ Colicy pains, purging, emesis in vomiting animals, more or less tympany and rumbling of the bowels, and surface coldness. _Treatment._ Give carbonates of the alkalies, magnesia or lime to precipitate the comparatively insoluble carbonate or oxide; or tannic acid or infusion of oak bark or galls. White of egg, milk and mucilaginous agents, and opium may be required to allay irritation. POISONING BY CHROMIUM. Chromic acid, chromate and bichromate of potash. Corrosive. Cause: Gastro-intestinal inflammation, albuminuria, hæmaturia, emaciation, digital ulcers and sloughs, colic. Diarrhœa, vertigo, stiffness, weakness. Lesions. Treatment: Emesis, stomach pump, demulcents.