ELECTRO-CHEMICAL POSITIONS OF WROUGHT-IRON, ETC. 



215 



Table I. 



Galvanometer Experiments with Bright Steel, Wrought Iron, and Cast-Metal Plates, Sfc. 



Inscription. , 



Percentage 



of Combined 



SOLUTION IN WHICH THE PLATES WERE IMMERSED. 



One-Fifth Normal Standard Sulphuric Acid. 



Wrought-Iron Plates {Bright), forming 



one Element with each of the following 



Bright Steel, &c, Plates. 



Plates covered with Scale (Magnetic 



Oxide) placed in Galvanic Connection 



with Bright Plates from the same 



piece of Steel, &c. 







Deflection of 



Galvanometer in 



Degrees. 



Electro-Chemical 



Position of the 



Metals. 



Deflection of 



Galvanometer in 



Degrees. 



Eleetro-Chemical 



Position of the 



Metals. 















Average. 



Highest. 





Average. 



Highest. 





Soft Siemens-Martin steel, 



0-170 | 



0- 7 

 0.0 



2-25 

 1-00 



P for 26 minutes 

 N afterwards 









Soft steel (Firth's), . 



0-460 | 



0-25 

 1-00 



0-25 

 1-25 



P for 2 minutes 

 N afterwards 









Wrought iron, .... 



Trace 















Soft Bessemer, .... 



0-150 j 



0-40 

 0-24 



2-00 

 0-25 



P for 60 minutes 

 N for 120 „ 









Hard Bessemer, 



0-510 



1-21 



1-75 



P 









Hard Siemens-Martin steel, 



0-720 



1-62 



2-00 



P 









Hard steel (Firth's), . 



1-407 



0-74 



2-00 



P 











r 



0-44 



1-25 



P for 12 minutes 



0-62 



1-00 



P for 5 minutes 



Cast metal,* .... 



2-010 < 



0-63 



0-90 



N afterwards 



0-12 



0-25 



N afterwards 



* Graphitic carbon, 1'50 per cent. 

 Remarks. 

 Each result is the average of about forty observations, taken at equal distances of time, each experiment 



extending over three hours. 

 It is interesting to compare the results of the above table and diagram I with table and diagram G. 

 A partial reversal of the galvanic positions of some of the steels appears to take place, when an 

 acidsolution is employed instead of sea-water, as previously pointed out. 



Experiments to ascertain the Galvanic Action caused by Plates of Wrought Iron 

 {the half of every Plate being Bright, the other half left with its Scale on). 



Eleven plates of wrought-iron (cut from the same large plate) were each 

 bent double, thus, the half of every plate polished bright, and the 

 other half left covered with scale just as it left the rolls, they were 

 then placed in a clean porous cell, Daniells battery, filled with sea- 

 water. 



Each plate was 4*12 inches square, and as there were eleven in 

 the whole series, this represents a total superficial area of 373-48 Fiw 2 

 sq. inches of scaled surface, and 373-48 sq. inches of bright surface, 

 though, of course, the action of a voltaic series like this would be different to 



