Wood's metal, also known as Lipowitz's alloy or by the commercial names Cerrobend, Bendalloy, Pewtalloy and MCP 158, is a metal alloy that is useful for soldering and making custom metal parts, but which is toxic to touch or breathe vapors from. The alloy is named for Barnabas Wood, who first created and patented the alloy in 1860. It is a eutectic, fusible alloy of 50% bismuth, 26.7% lead, 13.3% tin, and 10% cadmium by mass. It has a melting point of approximately . Applications Wood's metal is useful as a low-melting solder, low-temperature casting metal, high-temperature coupling fluid in heat baths, and as a fire-melted valve element in fire sprinkler systems in buildings. Medical gas cylinders in the United Kingdom have a Wood's metal seal, which melts in fire, allowing the gas to escape and reducing the risk of gas explosion. Wood's metal is commonly used as a filler when bending thin-walled metal tubes. For this use the tubing is filled with molten Wood's metal. After this filler solidifies, the tubing is bent. The filler prevents the tube collapsing. The Wood's metal is then removed by heating, often by immersion in boiling water. Other uses include making custom-shaped apertures and blocks (for example, electron-beam cutouts and lung blocks) for medical radiation treatment, making casts of keys that are hard to duplicate otherwise and making metal inlays in wood. Wood's metal is useful in machine shops and technical laboratories when alternative means of holding delicate parts become necessary. It is used as an additional hardened layer to allow the proper gripping and machining of an object. The object is immersed in melted Wood's metal to completely or partially coat it, forming a layer from a few millimeters up to few centimeters thick, depending on how the object will be held in place. After cooling, the new assembly is clamped by conventional means. This method is most useful for one-off or limited-production workpieces, when construction of a special clamping or holding jig would neither be cost-effective nor offer maximum holding capability. Wood's metal is also useful for repairing antiques. For example, a bent piece of sheet metal may be repaired by casting a Wood's metal die from an intact example: The low melting temperature of Wood's metal makes it unlikely to harm the original, and the damaged piece can then be clamped in the die and slowly tightened to form it