Lead, in its metallic state, is not injurious. It is, however, really acted on by acids, exposure to the atmosphere, &c., and converted into carbonate of lead. The chief compounds of this metal which have been found to produce poisonous effects are the acetate, subacetate, and the carbonate.
Acetate of Lead (Sugar of Lead).—This is sold as a glistening white powder, or in the form of crystalline masses resembling loaf sugar. It is more frequently used as a poison than either of the other compounds. It is very soluble in water and has a sweetish metallic taste. Three or four instances are recorded in which recovery has taken place after an ounce of this substance has been taken in solution.
Mr. Bancks, of Stourbridge, has reported the particulars of a series of cases of poisoning by the acetate of lead (Lancet, 5th May, 1849). It appears that thirty pounds of this substance were accidentally mixed at the miller’s with eighty sacks of flour. This was made into bread, from eating which 500 persons suffered severely. The chief symptoms were a sense of constriction in the throat and at the pit of the stomach, crampy pains round the navel, stiffness of the abdominal muscles, paralysis of the lower extremities, constipation, scanty urine, and the formation of a deep blue line round the gums. Although in many cases there was great prostration with other alarming symptoms, yet under the use of purgatives all recovered. It was noticed that after a temporary convalescence many of the symptoms returned in an aggravated form without any apparent cause. Sometimes there has been vomiting and purging, and there is great prostration, with cramps and convulsions.
Post-mortem Appearances.—They are not usually very distinct. The stomach and intestines have been found inflamed, and the surface of the former softened and, in the case of animals, corroded. There may be no characteristic signs in chronic poisoning.
Subacetate of Lead (Goulard’s Extract).—This substance is known to have proved fatal in three or four instances, after having caused great agony. It is a more powerful poison than the acetate. It is found in the shops as a whitish-colored liquid.
Carbonate of Lead (White Lead, Ceruse, &c.).—This is sold in heavy white masses, looking like chalk. It is readily acted on by acids, but is very insoluble in water.
Dr. Snow has reported an instance in which a child ate a portion, about the size of a marble, mixed up with oil; it died on the fourth day. Carbonate of lead derives its greatest interest from the chronic form of poisoning which it produces among white lead manufacturers, painters, &c., known as “the painters’ colic,” which too often terminates in “lead palsy.” In these instances the lead finds its way into the system by absorption from the digestive canal, the lungs, or the skin; producing its characteristic effects when a sufficient amount has been absorbed. It is this salt which is formed by the action of air and water upon lead.
The other preparations of this metal do not require any separate notice.
Treatment.—The sulphates of soda or magnesia should be freely given dissolved in water. Milk, or milk and eggs will be useful. If vomiting is absent, an emetic of sulphate of zinc should be administered, or the stomach-pump may be advantageously employed.
For a chemical antidote in poisoning by carbonate of lead Dr. Taylor recommends a mixture of vinegar and sulphate of magnesia.