Lay hare about an inch of a great nerve (of a frog), leading to any limb or musde. Let that end of the bared part which is farthest from the limb he in close contact with a bit of zinc. Touch the zinc with a hit of silver, while another part of the silver touches, either the naked nerve, if not dry, or, whether it be dry or not, the limh or muscle t o which i t leads. Violent contractions are produced in the limb ar muscle, hut not in any muscle on the other side of the zinc. Or, touch the bared nerve with a piece of zinc, and touch, with a piece of silver either the bared nerve, or the limh; no convulsion is observed, till the zinc and silver are also made t o touch each other. A fact so new, illustrated by many experiments and much ingenious reasoning which Professor Galvani soon published, could not fail t o attract the attention of the physiologists all over Europe; and the result of a vast number of experiments, equally cruel and surprising, has been from time t o time laid before the public by Valli, Fowler, Monro, Humbolt, and others.
The term "animal electricity" soon gave way to "Galvanism" in honor of its discoverer. Galvani believed that every animal organism was a source of electricity in some quantity, (vide: torpedo, gymnotus electricus, and silurus electricus) and that the vital processes were somehow linked intimately with this phenomenon. This theory was generally accepted until Volta, a professor in the University of Pavia, Italy, observed that when two metals and a liquid are combined to form a circuit, an electric current is produced, and further, that two different metallic wires are necessary to cause frog's legs t o shudder and contract; the galvanic effect being extremely weak or absent entirely when only one kind of metal is used. All this led the way toward the discovery of the Pile of Volta, reported in 1800.20 1Q
See "Primary-Cell-A Brief Historical Sketch," by C. J. Brockman, THIS 4, 770-80 Uune, 1927).
JOURNAL,
Motion Picture Films. The Bureau of Mines has available a number of motion picture films designed to illustrate the manufacture and proper utilization of motor gasoline and lubricating oils. The latest of these is entitled "The Power Within, or the Construction, Operation, and Care of the Internal-Combustion Engine," and is designed to familiarize the general motoring public with methods for the proper care and operation of the internal-combustion engine, thus tending to conserve the supply of the raw materials from which gasoline is derived. The bureau's latest addition to its motion picture library is "The Heat Treatment of Steel," made in coeperation with one af the large automobile manufacturing companies. This film shows that 1475 separate steel parts of a typical automobile must be given special heat treatment, forcibly illustrating the importance of this process in the automohile-manufacturing industry. Old-time methods of tempering steel are shown in sharp contrast with the various steps in modern heat treatment. Copies of these films may be obtained without charge, except for casts of transportation, from the Pittsburgh Experiment Station, U. S. Bureau of Mines, Pittsburgh, Pa.-News Edition, Ind. Eng. Chem., 7, 2 (Mch. 10, 1929).
