DR. J. P. JOULE ON SOME AMALGAMS. 119 



whether it was exposed to the action of air^ or was placed 

 under the exhausted receiver of an air-pump. 



The amalgam of iron^ whether solid or fluid, is at- 

 tracted by the magnet, and in the solid condition is capa- 

 ble of receiving a slight dose of permanent magnetization. 



In No. I, the iron, though apparently completely dis- 

 solved by the mercury, remained in the full possession of 

 its magnetic virtue. 



A portion of No. 2, weighing 87*69 grains, placed in a 

 piece of quill, was attracted by a magnet with a force equal 

 to 0*36 gr. 3*058 grains of iron wire, cut into small 

 pieces and placed in the same quill, were attracted by a 

 force of 0*94 gr. The quantity of iron contained by the 

 amalgam was i*2 grain. Hence it appeared that the iron 

 had lost very little of its magnetic virtue by combination 

 with the mercury. 



The following observations were made to discover the 

 position of the amalgam of iron in the electro-chemical 

 series. The galvanometer which was employed had a coil 

 I foot in diameter, composed of 400 convolutions of 

 wire I -40th of an inch in diameter. 



Positive Metal. 



Negative Metal. 



Deflection. 



Amalgamated zinc. 



Zinc. 



10° 



Zinc. 



Iron. 



42° 



Zinc. 



Copper. 



65° 



Amalgamated iron. 



Copper. 



15° 



Iron. Amalgamated iron. 5° 



It appears, therefore, that the amalgamation of iron 

 produces a contrary efi'ect to the amalgamation of zinc. 

 This is especially remarkable, as the amalgamated iron 

 contained no carbon, which must have existed to a certain 

 extent in the plate of iron with which it was associated. 



When amalgam of iron is left under water for a few 

 days, it becomes coated with rust. If shaken violently, it 



