440 Mr. Smee on the Cause of the Reduction of Metals 



yielded slowly silver, the hydrogen becoming at the same time 

 lessened. 



27. These last two results are interesting to the chemist, 

 lor It appears to open a path for investigation on the nature of 

 these very curious and now highly important combinations. 



28. Such were my results with platinized platinum and hy- 

 drogen; the hydrogen becoming absorbed and the metals being 

 reduced. It was found that chloride of platinum, chloride of 

 palladium, persalts of iron, chloride of gold, and nitric acid 

 yielded the oxygen most rapidly. It next became my endea- 

 vour to ascertain how far other metals, or different conditions 

 of the same metal, might be used ; and smooth platinum was 

 next the subject of experiment. With sulphate of copper or 

 persalts of iron no absorption however took place. 



29. Palladinized platinum was made the subject of experi- 

 ment; and when employed with hydrogen in a manner similar 

 to platinized platinum in sulphate of copper, it caused that 

 metal to be reduced. 



30. The effects of silver were then examined, and for that 

 purpose a piece, carefully cleaned by nitric acid, was immersed 

 in a solution of copper in contact with the hydrogen, but no 

 change occurred even after many days. 



31. No better result attended the employment of silver 

 sponge used for the same purpose. 



32. Nor did the black deposit of silver answer better to 

 effect the absorption of the hydrogen, and the reduction of the 

 metal from a solution of sulphate of copper did not occur. 



33. Copper, both in its bright and spongy states, was next 

 examined; in its bright state, cleansed by nitric acid, no 

 change occurred. 



34. In the spongy state it appeared to be of no greater 

 efficacy to cause the reduction of the metal. 



35. Considering the interest attached to carbon in the cinder 

 experiment, detailed in a former part of this paper, a piece of 

 carbon was exposed to the action of hydrogen and a solution 

 of copper, but, singular to state, no deposit of copper took place, 

 nor was any hydrogen absorbed. In fact I have no mecha- 

 nical method of charging coke with hydrogen, by which it can 

 be made to cause the reduction of the metals. 



36. The last set of experiments which I instituted upon the 

 reduction of the metals by hydrogen was the value of bibulous 

 paper to effect that object. In dilute chloride of gold appa- 

 rently no action after two or three days took place. 



37. In a solution of sulphate of copper, after many days, 

 no action apparently occurred with paper and hydrogen. 



