Skey. — On tJic Oxidation of Mercury. 583 



. 1. Clean mercury (as thrice distilled and then filtered 

 twelve times) shaken up with a small quantity of spring 

 water for a considerable time not only breaks up in semi-non- 

 coalescing globules, as one would expect from our present 

 knowledge, but, besides, imparts a slight though persistent 

 turbidity to the water. 



2. In distilled water the same effects follow, but they re- 

 quire a longer time to produce them. 



3. When aqueous solution of the caustic or carbonated 

 alkalies are substituted for the water these effects are rapidly 

 produced. 



4. In weak sulphuric acid mercury breaks up considerably 

 when shaken together after it has had contact for some time, 

 and the liquid also becon:ies turbid. 



5. If weak hydrochloric acid or iodide of potassium be 

 substituted for sulphuric acid turbidity is not produced, and 

 the mercury is not readily broken up. 



6. Hydrochloric acid, potassic cyanide, and potassic iodide 

 clear these turbid waters and saline solutions, and more or 

 less agglomerate the mercury. 



7. Mercury in strong solution of potash is weakly positive 

 to this metal in both weak solutions of potash and solutions 

 of sodic chloride. 



8. Mercury in solutions of potash is strongly positive to 

 itself in hydrochloric acid, and very strongly positive to itself 

 in nitric acid. 



9. Mercury in weak sulphuric acid is positive to mercury 

 in nitric acid. 



10. Mercury in potassic-cyanide solution is positive to 

 mercury in potash solution. 



Now, the only explanation of these facts appears to me to 

 be this : that in the experiments Nos. 1, 2, 3, and 4 the mer- 

 cury has combined with certain of the elements present, form- 

 ing in some cases oxides or carbonates, in other cases sub- 

 chlorides and subsulphates, and these compounds became 

 detached by the friction of the mercury on itself, thus pro- 

 ducing the turbidity described ; while the effect of the potassic 

 cyanide and iodide, also of the hydrochloric acid in No. 5 ex- 

 periment, is to dissolve these compounds, thus restoring the 

 normal transparency of the supernatant liquids. The mer- 

 cury, in fact, for the first series of experiments has (to use the 

 miners' very expressive phrase) floured ; had it not floured 

 there would not have been any turbidity produced, and it 

 would not have broken up permanently into small globules 

 as it did. 



In the cases where only distilled water was used, or sul- 

 phuric acid, it appears certain that the mercury must have 

 been directly oxidized by the air present therein. 



