Gooch and Read — Determination of Chlorine. 547 



weights of the ignited anode, cathode, and suspended silver com- 

 pound here also fell short of the weights of chlorine present 

 by 0*0039 grm. In this case the suspended precipitate was 

 brownish, and the clear filtrate deposited upon standing for 

 forty-eight hours a precipitate which, when filtered off and 

 treated with hydrochloric acid, and dried, weighed 0*0029 grm. 

 On standing for a week the filtrate threw down another slight 

 deposit. Silver oxide was plainly found at the anode, and the 

 behavior of the clear filtrate is suggestive of the formation of 

 silver hypochlorite and its subsequent transformation to insolu- 

 ble silver chloride and silver chlorate. 



In a third experiment, essentially similar to the first except- 

 ing the use of a platinum cathode, the formation of a deposit 

 of silver upon the cathode was distinctly visible. It is plain, 

 therefore, that the solution of silver from the anode, the 

 deposition of the silver upon the cathode, the production of 

 oxygen acids of chlorine (hypochlorous acid and chloric acid) 

 and possibly their silver salts, are phenomena likely to occur 

 in the electrolysis of hydrochloric acid with the use of the 

 silver anode. 



In subsequent experiments the rotating anode of the form 

 used by Hilclebrancl,* consisting of two circular disks of 

 platinum gauze of 300 meshes to the square centimeter, 5 

 centimeters in diameter and mounted 5 millimeters apart and 

 parallel to one another upon a perpendicular wire of platinum 

 used as the axis of revolution, was substituted for the stationary 

 anode. This apparatus was plated with silver by rotating it as 

 the cathode in a solution of potassium silver cyanide. After 

 plating, it was prepared for use by careful washing, drying, 

 and ignition to incipient redness in the tip of a Bunsen flame. 

 A 200 cm3 platinum dish was used as the cathode. The pure 

 hydrochloric acid employed was made up of approximately 

 X/10 strength. It was standardized by precipitating with silver 

 nitrate in the hot solution and weighing the silver chloride 

 filtered after standing over night and chilling. Parallel 

 determinations showed 0*4247 grm. and 0*4248 grm. of 

 chlorine in 100 cm3 . The residue left by evaporation of 25 cm3 of 

 the solution was found in parallel experiments, one at the 

 beginning and the other at the end of work, to be 0*0001 

 grm. and 0*0003 grm. 



In each experiment a portion of the standard acid, usually 

 25 cm3 , was drawn from a burette into the 200 cm3 platinum dish 

 which served as the cathode. The dish with contents was 

 adjusted, the anode set in the rotating apparatus, and the 

 solution so diluted that the anode dipped well under the liquid 

 while distant from the cathode by about l cm . The anode was 



* Jour. Amer. Chem. Soc, xxix, 450, 1907. 



