Film: "Bubble model of a metal", silent, 11 min.

Film: Bubble model of a metal. Film Title: Bubble model of a metal. Level: Upper elementary-Adult. Length: 11 minutes. Black and White, no sound, with captions. Description: This 1946 Cavendish Laboratory film illustrates the structure and mechanical properties of a metal. The model is 2-dimensional. The atoms are represented by bubbles about 1 mm. in diameter floating on the surface of a soap solution. The binding function of the free electrons of a metal is simulated by the capillary forces which hold the bubbles in a tight cluster. When blown under constant pressure from a fine nozzle about 1 cm. below the surface, the bubbles are very uniform in size. A regular raft of bubbles can be anchored between 2 parallel horizontal springs on the liquid surface. Slip takes place when one spring is translated parallel to the other one. The film discusses and show examples of the concepts of dislocations, holes, grain boundaries, compression, shear, and 'cold work'. MOLECULAR MODELS AND CRYSTAL STRUCTURE.