[A] In these experiments air was aspirated through an iron funnel having an area of 113 square inches (12 inches diameter), placed at a height of 1¹⁄₂ inches above the molten metal, and connected to an iron tube 3 feet in length and ¹⁄₂ inch in diameter. Inside the iron tube was a glass tube, one end reaching own to the top of the funnel and the other connected with a tube containing pure loose asbestos wool, and continued down to a tightly stoppered bottle holding dilute sulphuric acid. Another glass tube connected this bottle with an aspirator. The asbestos tube was weighed before and after each test, and the asbestos then treated with nitric acid, and the lead determined volumetrically. In none of the tests made was lead found in the bottle containing sulphuric acid. Were there nothing else to consider but escape of lead fume from a pot or bath of molten metal, obviously hooding over of the bath and removal of the fume from the atmosphere of the workroom would be unnecessary until this temperature was reached. Usually, however, the bath is kept standing exposed to the air, and the oxide which forms on the surface has to be skimmed off periodically, and whenever the ladle is emptied a small cloud of dust arises. Or at times, in certain processes, chemical interaction takes place in the bath, as in the dipping of hollow-ware articles previously cleaned in hydrochloric acid, with evolution of fume of volatile chloride of lead. Any vessel, therefore, of molten metallic lead in which skimming is necessary, or in which chemical action gives rise to fume, requires a hood and exhaust shaft, even although the temperature is little, if at all, above the melting-point--unless, indeed, a separate exhaust can be arranged for the removal of the dust immediately above the point where the skimmings are deposited.