868 C. A. Peters — Electrolysis of Sodium Chloride 



At one end the wires were joined and went through a 

 porcelain tube to a binding post (6') on top. At the other end 

 each wire went separately to posts (a) and (b) on top. This 

 furnished three heats with the 110 volt direct current. Con- 

 nection a to J gave a temperature of 285°, a to c, or b to c, 400°, 

 and a and b, together, to c 580°. The insulation on the sides 

 was bright metal, aluminum or tin, in three layers each packed 

 loosely with powdered magnesia or loose asbestos between and 

 the whole surrounded by wood. The top and bottom was 

 composed of three layers of the asbestos-soapstone board packed 

 with less than a centimeter of magnesia between each. A 

 sliding door on the bottom allowed a draft when desired. The 

 same mica cover that was described under the Heating Cruci- 

 ble closed the top. 



Mercury Still. — The apparatus described by Hulett and 

 Minchin* was used. 



Thermometers. — Nitrogen thermometers were used to deter- 

 mine temperatures over 350°. In determining the temperature 

 of the electric furnace two thermometers — one certified — gave 

 the same results. 



Chemicals. 



Sodium Chloride. — The salt was the pure article of German 

 origin further purified by one precipitation with hydrochloric 

 gas. It was fused in platinum and bottled. Two liters of 

 solution, made up at once after the fusion, contained ll - 6920 

 grms. of salt. 



Hydrochloric Acid. — The pure acid was diluted and stand- 

 ardized. Two 100 cm3 portions precipitated at considerable 

 dilution gave, including the residue after evaporation of the 

 filtrates mostly in platinum, 1'4768 and l - 4770 grms. of fused 

 silver chloride respectively. 



Mercury. — The ordinary redistilled mercury of commerce 

 was used. After use in some preliminary experiments and 

 before using in the experiments quoted it was subjected to 

 triple distillation. No residue was found after the first distil- 

 lation. 



Procedure. 



Plating Anode. — The platinum gauze anode was plated from 

 an ammoniacal solution of silver nitrate to which ammonium 

 oxalate had been added. f To insure an even deposit of silver 



* Physical Review, xxi, 395, 1905. 



f It was found convenient to add crystalline ammonium oxalate after 

 solution of the silver nitrate by ammonia had been effected. The oxalate 

 dissolved as the anode was rotated during the plating. 



