The most eminent authorities have recently shown that the dried film of linseed oil, unless united with a pigment that combines chemically and forms a water-proof coating with it, actually absorbs water very much like a sponge. Where water will go air will also go, and we thus have in direct contact with the iron oxide of the paint, which does not combine chemically with oil, those elements, air, moisture, and organic matter, which cause the iron to become a carrier of oxygen and a destroyer of what it is in contact with. It is well known that iron paint darkens with age; this is caused largely by the iron oxide losing oxygen, which is partly transferred to the oil, burning it up and destroying its tenacity, as may be seen by examining iron structures painted for some time with iron paint or metallic brown, the paint being found extremely brittle and in feathery scales. This is not all the damage that is done. The iron oxide in the paint becomes a carrier of oxygen to the very metal it was designed to protect, and the process of corrosion is commenced and carried on under the paint, which eventually peels or scales off, the surface of the metal being found more or less oxidised and corroded. Asphalt and iron oxide being thus shown to be entirely incapable of preserving the iron, it remains for us to consider the effect of red lead. This pigment has the property of forming with linseed oil a hard elastic coating, clinging with great tenacity to the metal. It has no oxidising effect on iron, and does not act as a carrier of oxygen from the atmosphere after the paint has set, neither does it render the oil brittle nor promote rust. When red lead fails, it is principally by gradual wear or friction from the outside. It does not scale or blister, which both asphalt and iron oxide paints will do, thereby requiring a thorough scraping and removal of old material before a new coat can be applied. Any red lead pigment adhering to the metal forms a permanent base for subsequent paintings, and is utilised in further preserving the metal. The U.S. Government specifications for ironwork in the new Library Building of Congress provide that “all the work not Bower-Barffed must be given one coat of pure red lead paint--not metallic paint of any kind, but pure red lead--before leaving the shop and becoming rusted.”