294 MclUiiney ^Action of Ferric Chloride on Metallic Gold, 



amount of gold and acid but twelve times as mucli ferric chlo- 

 ride, and this tube was boiled for several minutes before sealing 

 and sealed while still boiling in order to remove the air. After 

 heating the tubes the liquid in the first was found to contain 

 0-0109 gold in solution, while in the liquid in the second tube a 

 slight test for gold could be obtained only with difficulty, and 

 it seemed likely that this small amount of gold might have 

 been dissolved before the tube was boiled and after the materials 

 had been added. Another small tube was prepared containing 

 about a gram of ferric chloride dissolved in concentrated 

 hydrochloric acid and the tube boiled to expel air and sealed 

 while boiling. This tube was placed in a larger tube contain- 

 ing concentrated hydrochloric acid and 0*500 gram gold and 

 the liquid in the larger tube also boiled for some minutes and 

 sealed boiling. The smaller tube was then broken by shaking, 

 allowing the iron to mix with the acid and come in contact 

 with the gold without access of air. This tube was then 

 heated as the others had been and the liquid tested for dissolved 

 gold. E'ot a trace was to be found. 



It thus appears that hydrochloric acid in presence of air is 

 without action on metallic gold, that ferric chloride is without 

 action on gold unless oxygen is present, but that ferric chloride 

 acts as a very efficient carrier of chlorine in the presence of 

 hydrochloric acid and oxygen. This fact helps to account for 

 the solubility of gold in mine waters and in other waters con- 

 taining iron, acid, and common salt. 



Metallurgical Laboratory, Columbia University, N. Y. 



