_Method of Extraction from the Stomach._--Dry the contents of the stomach or portions of the liver, etc., and incinerate in a porcelain crucible. Treat the ash with nitric acid, dry, and dissolve in water. The solution of nitrate of lead may now have the proper tests applied. _Tests._--Sulphuretted hydrogen gives a black precipitate; liquor potassae, white precipitate; sulphuric acid, white precipitate, insoluble in nitric acid; iodide of potassium, a bright yellow precipitate. A delicate test for lead in water is to stir the water, concentrated or not, with a glass rod dipped in ammonium sulphide: a brown coloration is produced. One-tenth of a grain of lead in a gallon of water may be detected. Chronic lead-poisoning is an 'industrial disease,' and, being an occupation risk, its victims are entitled to compensation at the hands of their employers. In case of death, compensation has been awarded even when at the autopsy the patient has been found to have suffered from acute tuberculosis of the lungs. The responsibility of apportioning the monetary value of disablement resulting from the action of the lead rests with a judge or jury, who are guided by the expert medical evidence available. Diachylon, or lead-plaster, is largely used as an abortifacient. XXV.--COPPER AND ITS PREPARATIONS Poisoning with copper salts is rare. The most important are the sulphate, subacetate, and arsenite. =Sulphate of Copper= (bluestone, blue vitriol) in half-ounce doses is a powerful irritant. Has been given to procure abortion. =Subacetate of Copper= (verdegris) occurs in masses, or as a greenish powder. Powerful, astringent, metallic taste. Half-ounce doses have proved fatal. _Symptoms._--Epigastric pain, vomiting of bluish or greenish matter, diarrhoea. Dyspnoea, depression, cold extremities, headache, purple line round the gums. Jaundice is common. A _chronic_ form of poisoning may occur, with symptoms closely resembling those of lead. _Post-Mortem Appearances._--Inflammation of stomach and intestines, which are bluish or green in colour. _Treatment._--Encourage vomiting. Give albumin or very dilute solution of ferrocyanide of potassium. _Method of Extraction from the Stomach._--Boil the contents of the stomach in water, filter, pass hydrogen sulphide, filter, collect precipitate and boil in nitric acid, filter, dilute filtrate with water and apply tests. In the case of the solid organs, dry, incinerate, digest ash in hydrochloric acid, evaporate nearly to dryness, dilute with water, and test. _Tests._--Polished steel put into a solution containing a copper salt receives a coating of metallic copper. Ammonia gives a whitish-blue precipitate, soluble in excess. Ferrocyanide of potassium gives a rich red-brown precipitate. Sulphuretted hydrogen gives a deep brown precipitate. XXVI.--ZINC, SILVER, BISMUTH, AND CHROMIUM The salts of zinc requiring notice are the sulphate and chloride.