386 0. A. Peter*— Reactions in a System of Chloride. 



Am. XLI. — 'Ha Reactions in <i System of Nickel or Plati- 

 num, Mercury, and Sodium Chloride; by Cii.vki.es A. 

 Pbtebs. 



[contributions from the Kent Chemical Laboratory of Yale Univ. — oexxvii.] 



IUkino the progress of work upon the electrolysis of sodium 

 chloride with the mercury cathode." it was noticed that when 

 the outer cell containing sodium hydroxide, sodium chloride in 

 solution over mercury, and nickel wire in contact with both 

 liquids was allowed to stand several days a scum formed on 

 the surface of the mercury. Upon shaking the liquids in the 

 separators funnel and drawing off the mercury the remaining 

 liquid appeared turbid. Under the microscope transparent 

 colorless crystals were easily seen mixed with air bubbles. 



To study the conditions under which these crystals might be 

 formed and to determine their identity, such systems as com- 

 pose the outer cell of the electrolytic apparatus were made and 

 allowed to stand. These consisted of Erlenmeyer beakers con- 

 taining 300 grms. of mercury, sodium chloride solutions of 

 different strengths and an inverted V-shaped piece of nickel 

 wire. 



In a day a scum was visible on the surface of the mercury 

 which accumulated as the systems stood, seemingly more dense 

 in the immediate vicinity of the wire, aud, after several weeks 

 showed, increasing in distinctness as the time increased, the 

 familiar " apple-green " color. The nickel was corroded. The 

 amount of the green precipitate increased faster when a greater 

 surface of nickel was exposed in the salt solutiou. 



This precipitate, crystalline under the microscope, wheu col- 

 lected on the filter and well washed with water, gave tests for 

 nickel but none for mercury, chlorine, or sodium. It turned 

 black upon ignition. By these characteristics the crystalline 

 substance was identified as nickelous hydroxide. 



Tupputif has formed crystalline nickel hydroxide from 

 nickel carbonate dissolved in ammonia. Crystals made by the 

 hasty evaporation of such a solution appeared similar to those 

 obtained from the mercury -nickel-salt systems. 



The solution over the mercury showed a tendency to develop 

 alkalinity very slowly. In one case a beaker with the mer- 

 cury, water, nickel wire, and a piece of red litmus paper — 

 without sodium chloride — stood 24 hours. The litmus paper 

 was still reddish and showed no trace of blue or purple, but 

 upon adding a cubic centimeter of saturated salt solution the 

 litmus was decidedly bluish when observed two hours later. 



*This Journal, preceding article, 

 t Gmelin— Kraut, 1910. Bd. V, Abt. 1. p. 44. 



