Archive image from page 106 of Directions for laboratory work in Directions for laboratory work in physiology directionsforlab1906lomb Year: 1906 POLARIZATION OF ELECTRODES. 83 glass rod ; and fix the rod in a clamp on the support which holds the muscle clamp, in the moist chamber. Dry the wires just used as electrodes, and connect them to the zincs; with a dropper put about half a cubic centimeter of zinc sul- phate into the boots, being careful not to spill any of it on the outside of the electrodes. Then insert the zincs into the tops of the boots. Experiment.—Lay the nerve across the tip
Archive image from page 106 of Directions for laboratory work in Directions for laboratory work in physiology directionsforlab1906lomb Year: 1906 POLARIZATION OF ELECTRODES. 83 glass rod ; and fix the rod in a clamp on the support which holds the muscle clamp, in the moist chamber. Dry the wires just used as electrodes, and connect them to the zincs; with a dropper put about half a cubic centimeter of zinc sul- phate into the boots, being careful not to spill any of it on the outside of the electrodes. Then insert the zincs into the tops of the boots. Experiment.—Lay the nerve across the tips of the boots and re- peat the experiment made before. If the electrodes are not polariza- ble, closing and opening the bat- tery circuit should give the same effect as before, but there should be no response to the movements of the key which follows. On completing the day's work, the non-polarizable electrodes must be thoroughlv washed and soaked Eig. 21. Method of arrang- ing non-polarizable boot elec- trodes in moist chamber. A, zinc; B, porcelain boot; C, nerve; D, wires to short- circuiting key. over night in normal salt solution. Pfliiger's Law. The polarization current which is set up, is strongest at first and gradually fades away; consequently in the course of an experiment, the student often sees the effects of the opening and closing of strong, medium, and weak currents. These effects, which differ with the direction in which the current flows through the nerve, have been classed under what is known as Pfliiger's law. To recall this law one has only to remember the following facts, viz.: i, that the closing excitation develops in the region of the kathode, and the opening excitation near the anode; 2, that the closing excitation is the stronger; 3, that by strong currents the conductivity of the nerve is lessened at the anode during the flow of the current, and at the kathode at the instant that the current ceases; 4, with an ascending current the
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