200 



MR THOMAS ANDREWS ON THE RELATIVE 



One interesting fact observed in the course of these experiments is that 

 ■wrought iron and steels, &c, are not static in their relative electro-chemical posi- 

 tions, and when immersed in sea-water, or other solutions in connection with each 

 other, cannot exactly be regarded as constant elements. The relative electro- 

 chemical position is also varied, according to the nature of the solutions employed. 



The chemical composition of the iron and steel bars and plates employed in 

 the following experiments is shown by the accompanying analyses. 



Table B. 



Analyses of Steel, Wrought and Cast-iron Plates. Percentage Composition. 



Description. 



Graphitic 

 Carbon. 



Combined 

 Carbon. 



ilicoii. 



Sulphur. 



Phosphorus. 



Manganese. 



Iron 

 (by diffeienee). 



Soft Siemens-Martin steel, 





■170 



071 



•117 



•077 



•627 



98-938 



Soft steel (Firth's), . 





•460 



074 



•025 



•210 



•184 



99-047 



Wrought iron, 





Trace. 



•206 



•024 



•454 



•396 



98-920 



Soff Bessemer, 





•150 



•015 



•111 



•064 



•540 



99-120 



Hard Bessemer, 





•510 



•068 



•113 



•087 



1-153 



98 069 



Hard Siemens-Martin steel, . 





•720 



•080 



■102 



•143 



1-239 



97-716 



Hard steel (Firth's), 





1-407* 



•121 



•056 



■080 



•360 



97-976 



Cast metal, .... 



1-500 



2-010* 



•410 



•250 



•450 



•650 



94-730 



* By combustion. 



Some of the physical properties of the bars employed are indicated by the 

 following tests to which they were submitted : — 



Table C. 



Description 



Original. 



Ultimate Stress. 



Fractured. 



Stress 

 per Square 



Inch of 

 Fractured 



Area. 



Extension 

 in 10 Inches. 



Appearance 



of 



Fracture. 



Size. 



Area. 



Total. 



Per Square Inch 

 of Original Area. 



Size. 



Area. 



Difference. 



Inch. 



Per 



Cent. 



Area 



Per 



Cent. 



Tungsten steel, 



Hard steel, 



Bessemer steel, 



Puddled steel, 



Puddled steel ) 

 (chilled), ] 



Wrought iron, 



Soft Siemens- ) 

 Martin steel, \ 



Cust metal, 



Inch. 

 •30 



•298 

 •297 

 •296 



•298 



•296 



•38 



•293 



Sq. in. 



•070 



•0697 

 •0693 

 •0688 



•0697 



•0688 



•113 



•0674 



lbs. 

 12,561 



10,967 

 9,851 

 7,180 



6,322 



6,028 



8,328 



1,436 



Lbs. Tons. 



179,443 = 80-1 



157,346 = 70-2 

 142,150 = 63-4 

 104,361=466 



90,703 = 40-5 



87,618 = 39-1 



73,699 = 329 



21,305= 9-6 



Inch. 

 •27 



•289 

 •275 

 •257 



•295 



•284 



•25 



•293 



Sq. in. 

 •057 



•0656 

 •0594 

 •0518 



•0683 



•0633 



•049 



•0674 



■013 



•0041 

 •0099 

 •0170 



■0014 



•0055 



•064 



•0000 



18-6 



5-8 

 14-2 

 24-7 



2-0 



7-9 



566 



o-o 



lbs. 

 220,368 



167,179 

 165,841 

 138,610 



92,562 



95,229 



169,959 



21,305 



73 



•12 

 •16 



•27 



•07 



■11 



1-97 



•00 



7 3 



1-2 

 1-6 



2-7 



0-7 



1-1 



19-7 



o-o 



( 10 % silky 

 \ 90 % granular 



100 % granular 



100 % granular 



100 % silky 



( 35 % silky 

 \ 65 % granular 



100 % fibrous 



100 % silky 



( 100 % granular 

 I (mottled) 



