In experiments made by one of us, which are quoted later, it has been shown that an isolated loop of intestine allows the absorption of a soluble lead salt (chloride) when there is no food present in the loop. As the food mass proceeds through the length of the intestine more and more sulphur is set free, and an opportunity arises for the fixation of the lead as a sulphide, but even as a sulphide it is slightly soluble. Probably, however, most of the lead becomes absorbed long before it reaches the stage at which free sulphur or sulphuretted hydrogen exists for the formation of sulphide. It is highly probable that lead, in common with a number of other heavy metals, including arsenic, is absorbed gradually in the upper part of the intestine, and re-excreted in the lower. Such an hypothesis is undoubtedly strongly supported by the remarkable staining of the large intestine and the ileo-cæcal valve. The exact mechanism of the absorption of lead from its compound with albumin or peptone as a lead peptonate or albuminate is very difficult to state at present; lead albuminate is undoubtedly insoluble in water or normal saline and in albumin. The process of absorption, then, of the metal lead from the gastro-intestinal canal is very closely related to the absorption of other heavy metals, and the fact that animals after very large doses of lead salts administered via the mouth show hæmorrhages in the intestinal wall, in addition to hæmorrhages in other parts of the body, with occasional distinct ulceration, suggests a localized coagulative action on the vessels in the wall of the intestine as the probable origin of the ulceration. A consideration of this problem of lead absorption from the intestine--probably only the minutest quantity of lead, if any, is absorbed from the stomach direct--is one of considerable importance in the prevention of such lead poisoning as is attributable to swallowing lead. No work in a lead factory should be commenced in the morning without partaking of food, because if food be present the opportunities for absorption of lead are greatly diminished, and of all foods the one to be recommended as the most efficient is milk, or cocoa made with milk. The absorption of dust through the lung is probably an exceedingly complicated reaction, and Armit’s experiments with nickel carbonyl probably give the clue. He found that in nickel carbonyl poisoning the volatile product was split up on the surface of the lung cells, the metallic portion passing onwards into the lung itself, to be eventually absorbed by the serum.