Formerly the use of arsenic in the manufacture of colours was great, especially of _emerald (Schweinfurter) green_. This is made by dissolving arsenious acid in potash with addition of acetate of copper. Drying and grinding the material constitute the main danger. Scheele’s green is another arsenical colour. Use of _arsenic colours_ is becoming less and less. But in colour printing of paper and colouring of chalk they are still employed. They are used, too, as mordants in dyeing, but cases of poisoning from these sources in recent years are not to be found. The dust in many glass works contains, it is stated, as much as 1·5 per cent of white arsenic. Despite the numerous opportunities for arsenical poisoning in industries it is rare or, at any rate, is only rarely reported. ARSENIURETTED HYDROGEN POISONING.—Industrial poisoning from arseniuretted hydrogen is caused mostly by inhalation of the gases developed by the action on one another of acids and metals which contain arsenic. Hydrogen gas as usually prepared for filling balloons gives occasion for poisoning. In Breslau in 1902 five workmen became affected, of whom three died from inhalation of arseniuretted hydrogen gas in filling toy balloons.[1] Further, use of hydrogen in lead burning may expose to risk, and also preparation of zinc chloride flux. Of thirty-nine recorded cases of arseniuretted hydrogen poisoning twelve were chemists, eleven workers filling toy balloons, seven aniline workers, five lead smelters, three balloonists, and in one the origin could not be traced. Nineteen of these proved fatal within from three to twenty-four days.[2] Cases are recorded (1) in the reduction of nitroso-methylaniline with zinc and hydrochloric acid; (2) in the preparation of zinc chloride from zinc ashes and hydrochloric acid; (3) from manufacture of zinc sulphate from crude sulphuric acid and zinc dust; (4) in spelter works in the refining of silver from the zinc crust with impure hydrochloric acid; and (5) in the formation room of accumulator factories. The English factory inspectors’ report describes in 1906 occurrence of three cases in an electrolytic process for the recovery of copper in which the copper dissolved in sulphuric acid was deposited at the cathode, and hydrogen at the lead anode. In the 1907 report mention is made of two cases, one affecting a chemist separating bismuth from a solution of bismuth chloride in hydrochloric acid, and the other (which proved fatal) a man who had cleaned a vitriol tank. The poisoning resulting from ferro-silicon is in part referable to development of arseniuretted hydrogen gas. ANTIMONY It seems doubtful if industrial poisoning can really be traced to antimony or its compounds; generally the arsenic present with the antimony is at fault. Erben[1] considers that industrial antimony poisoning occurs among workmen employed in smelting antimony alloys in making tartar emetic through inhalation of fumes of oxide of antimony.