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A DEMONSTRATION EXPERIMENT OF ELECTROLYTIC ! OXIDATION AND REDUCTION C. E. WmTE, UNIVERSITYOF MARYLANLL COLLEGE PARK,MARYLAND Pour a sufficient quantity of gelatin solution containing 1% NaCl inte the bend of a U tube so that the two arms will be separated. Cool the; gelatin to solidify it. Place a very dilute solution of ferric chloride containing a little potassium thiocyanate in one side of the tube, and a ferrous: chloride solution of a like concentration, also containing potassium thio-i cyanate, in the other side. The ferric chloride should be only sufficiently concentrated to give the characteristic red coloration with potassium thiocyanate. Platinum electrodes should be used. When the negative pole is placed in the ferric chloride and the positive pole in the ferrous chloride solution, in a short time the ferric ion will be reduced to ferrous. and the ferrous ion oxidized to ferric. The colors of the solutions will now,
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be reversed; the blood red (showing ferric ions) will appear at the anode and the colorless (showing absence of ferric ions) at the cathode. The time required for the reaction to take place will of course depend upon the strength of the current and upon the strength of the solution.
