A laboratory manual of electrotherapeutics . rmed the litmus paper on the hand will notchange color, but a piece in contact with the metal of theelectrodes will change color. The strength of currentbeing weak you should allow it to flow long enough to givemarked results. This experiment shows the value of covered elec-trodes and suggests the rule: When using the galvanic or direct current, never place bare or non-porous electrodes in contact with the skin or 0mucous membranes unless you wish to obtain at the points of contact the effect of free acid or free alkali. Experiment 53.—Electrolize a
A laboratory manual of electrotherapeutics . rmed the litmus paper on the hand will notchange color, but a piece in contact with the metal of theelectrodes will change color. The strength of currentbeing weak you should allow it to flow long enough to givemarked results. This experiment shows the value of covered elec-trodes and suggests the rule: When using the galvanic or direct current, never place bare or non-porous electrodes in contact with the skin or 0mucous membranes unless you wish to obtain at the points of contact the effect of free acid or free alkali. Experiment 53.—Electrolize a solution of NaCl,using carbon electrodes. Notice the odor of free , use iron electrodes and notice that less chlorine isgiven off, but that the anode is being corroded, giving alight colored solution of iron salt near the anode. Finallythe alkali liberated at the cathode will pass over by dif-fusion and cause a precipitate of ferrous and ferrichydrates. Iron salts cause more or less discoloration of OF ELECTROTHERAPEUTICS. 43. Fig. 25. Chloride of Silver Battery. the tissues in which they are set free. For this reason inminor surgical operations such as the removal of superflu-ous hairs, moles, warts, etc., especially on the exposed parts of the body, thecathode rather than theanode should be em-ployed. Experiment 5_|.—Electrolize a solutionof Na2S04 using pla-tinum electrodes anda simple voltaic the galvano-meter, B terminals, incircuit and have theelectrodes in positionbefore closing the circuit by placing the battery plates inthe liquid. Upon closing the circuit observe the galvano-meter needle and explain why it returns to zero so quickly.(T. 487). Now use one of your bichromate cells in asimilar manner and explain the difference in behavior. Experiment 55.—Polarized electrodes constitute anindependent source of E, M. F., which acts in an oppo-site direction to that of the electrolizing current. Thiscan be shown in the following manner. Place i
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