Lead. In its metallic state, it is generally considered inert, although persons who are long exposed to its influence, as by handling it, become affected with lead poisoning. Its salts exercise a powerful influence on the animal economy. It is the basis of several important preparations.
Dr. Pereira: - "In small doses they act on the alimentary canal as astringents, checking secretion, and causing constipation. After absorption, the constitutional effects of lead are observed, the arteries become reduced in size and activity, the pulse becomes smaller, and frequently slower also; the temperature of the body is diminished, and sanguineous discharges, whether natural or artificial, are frequently checked, or even completely stopped. This constringing and sedative effect seems extended to the secreting and exhaling vessels; the discharges from the mucous membranes, the exhalations from the skin, and the urine, being diminished in quantity. Thus we observe dryness of the mouth and throat, greater solidity of the alvine secretions, diminution of the bronchial secretion, and of cutaneous exhalation. When the system becomes impregnated with the metal, it occasions a peculiar blue or leaden discoloration of the gums, mucous membrane of the mouth, and teeth. Salivation, and a bluish colour of the saliva, have also been observed occasionally. In very large doses, some of the salts of Lead, the acetate for example, act as irritant and caustic poisons, giving rise to the usual symptoms indicative of gastro-enteritis." The diseases produced by exposure to the influence of Lead or its preparations (as in painting and other trades), or by a large and continued use of plumbaceous salts, are, - 1, Colic; 2, Metallic Rheumatism; 3, Paralysis; 4, Disease of the Brain, called Encephalopathy. Dr. A. T. Thompson regards the carbonate as the only poisonous salt of Lead, and although the opinion has not received general assent, it is certain that much larger doses of the Acetate of Lead can be given internally with safety, if combined with the use of Acetic Acid (thus preventing its conversion into a carbonate), than if given without it. It is eliminated from the system by the urine, the perspiration, the milk, and probably by the bowels. Mr. Blake* observes that the acetate alters the physical character of the blood, no perfect coagulation taking place when it has been injected into the veins.
* Beng. Dispensatory, p. 509.
Mat. Med., vol. i. p. 783.
2108. The post-mortem appearances in one case of poisoning by Goulard's Extract, are described by Christison. The lower end of the gullet, the whole stomach and duodenum, a part. of the jejunum, and the ascending and transverse colon, were greatly inflamed, and the villous coat of the stomach appeared as if it had been macerated. The stomach contained six ounces of a reddish brown fluid, which yielded lead globules, when the residue was subjected to reduction. Mr. Blake found, in animals killed by injecting the salts into the veins, that the lungs were engorged and hepatized; livid spots were observed on their surface, and the air-passages were either impermeable, or filled with a frothy fluid.