Franklin Peale Peale designed a new machine to cut planchets, or blanks, from metal strips. This machine remained in use, almost unmodified, until 1902. Another of the steam-powered machines Peale had installed on his return was a milling machine, which was used to "upset" the coin—to form a rim around it. A Contamin portrait lathe was imported from France and installed at the Philadelphia Mint in 1837. Prior to this time, all coin dies for American coins had to be made individually, by hand at Philadelphia. Once the lathe was installed, they could be reproduced mechanically by the pantograph-like device. The first
Glass-to-metal seal dark. Oxygen-free copper has to be used if the metal comes in contact with hydrogen (e.g. in a hydrogen-filled tube or during handling in the flame). Normally, copper contains small inclusions of copper(I) oxide. Hydrogen diffuses through the metal and reacts with the oxide, reducing it to copper and yielding water. The water molecules however can not diffuse through the metal, are trapped in the location of the inclusion, and cause embrittlement. As copper bonds well to the glass, it is often used for combined glass-metal devices. The ductility of copper can be used for compensation of the thermal expansion