Hot foil trick Hot foil trick The hot foil trick is a magic trick in which the magician places a small piece of tin or aluminium foil in a volunteer's hand, and the foil begins to rapidly increase in temperature until the volunteer has to drop it to avoid scalding their hand, and the foil is reduced to ashes on the ground. This effect is achieved by, shortly before performing the trick, surreptitiously exposing the foil to a chemical (such as mercury(II) chloride ) which will cause it to rapidly oxidise. This trick can be very dangerous, since many of the chemicals used
Foil bearing are: Foil bearing Foil bearings, also known as foil-air bearings, are a type of air bearing. A shaft is supported by a compliant, spring-loaded foil journal lining. Once the shaft is spinning fast enough, the working fluid (usually air) pushes the foil away from the shaft so that no contact occurs. The shaft and foil are separated by the air's high pressure, which is generated by the rotation that pulls gas into the bearing via viscosity effects. A high speed of the shaft with respect to the foil is required to initiate the air gap, and once this has been