Note 721 — ADULTERATION OF WINE.

[The solvent action of water upon lead is highly interesting on account of the very general use of leaden pipes and cisterns lined with this metal. From the researches of Lieut.-Col. Yorke, published in the Philosophical Magazine for August 1834 and January 1846, it would appear that a bright leaden vessel containing pure water, such as distilled water, and exposed to the air, soon becomes oxidized and corroded; oxide of lead being readily detected in solution by means of sulphuretted hydrogen and other sensitive tests; but river and spring water exert a much less or no such solvent power, the carbonates and sulphates in such water preventing it. It is on this account that leaden vessels are used with such impunity, the crust which forms upon the metal entirely preventing all further action. However, as this crust consists partially of carbonate of lead, which is a very dangerous poison, great care should be taken on cleaning or scraping such cisterns to avoid using the water in which particles of the salt may have become diffused. Leaden cisterns are sometimes rendered unsafe in consequence of iron or zinc pipes being soldered or let into them, thus giving rise to galvanic action, which greatly facilitates the solution of the lead.]