XI, A, 4 Heise and Clemente: Galvanized Iron 139 



Table II. — Removal of zinc from galvanized iron by hnmersion. 



Exper- 

 iment 

 No. 



Solution used. 



Weight 



of 

 sample. 



Loss on immer- 

 sion. 



Remarks. 







Grams. 



Grams. 



P. ct. 





6 



Sodium peroxide (Meyer 

 method) . 



8.494 



0.830 



9.77 





6 



Nitric acid (concentrated) 









Rapid and complete dissolu- 













tion. 



7 



Hydrochloric acid (sp. gr. 1.2).— 



5.773 



0.651 



9.55 



Loss after 30 minutes addi- 

 tional, 0. 001 gram. 



8 



Hydrochloric acid (25 per cent 

 by volume). 



5.094 



0.495 



9.73 





9 



Sulphuric acid (50 per cent by 









Action is very slow, but iron 





volume) . 









is attacked. 



10 



Sulphuric acid (25 per cent by 

 volume) . 



4.957 



0.497 



10.02 



Action continues indefinitely. 



11 



Sulphuric acid (5 per cent by 

 volume) . 



5.348 



0.505 



9.44 



Loss after 80 minutes addi- 

 tional, 0. 002 gram. 



12 



Sodium bisulphate (concen- 

 trated). 



4.413 



0.417 



9.45 



Loss after 18 hours additional, 

 0. 002 gram. 



13 



Phosphoric acid (26 per cent by 

 volume) . 



5.182 



0.496 



9.57 



Loss after 60 minutes addi- 

 tional, nil. 



14 



Phosphoric acid (2 per cent by 

 vohime) . 



4.228 



0.400 



9.45 





15 



Acetic acid (25 per cent by vol- 

 ume). 



5.822 



0.560 



9.61 



Required 24 hours for com- 

 pletion. Loss after 5. 5 hours 

 additional, 0. 0025 gram. 



16 



Lead acetate 



5.123 



0.496 



9.68 



Loss after 90 minutes addi- 













tional, 0. 0015 gram. 



17 



Lead acetate plus sodium hy- 

 droxide. 



5.027 



0.468 



9.30 



Loss after 20 hours additional, 

 0. 0015 gram. 



18 



Lead acetate plus acetic acid 



4.705 



0.428 



9.09 



Loss after 90 minutes addi- 

 tional, 0. 0005 gram. 



19 



Lead nitrate 



4.435 



0.303 



6.83 



Deposit is hard and adherent. 



20 



Lead nitrate plus nitric acid 



4.653 



0.428 



8 9.19 



Action is slow. 



21 



Lead nitrate plus sodium hy- 

 droxide. 



4.257 



0.402 



9.44 



Deposit is not readily re- 

 moved. Loss after 18 hours 

 additional, 0. 0035 gram. 



22 



Lead chromate plus sodium hy- 









No action. 





droxide. 











23 

 24 



Cadmium nitrate 









Do. 

 Action is very slow; coating 



Cadmium nitrate plus ammo- 



4.159 



0.398 



9.57 





nium hydroxide. 









is hard to remove. 



25 



Copper sulphate plus ammo- 

 nium hydroxide. 



4.063 



0.S94 



9.70 



Action is very slow. 



26 



Copper sulphate plus tartaric 

 acid plus potassium hydroxide. 



3.953 



0.381 



9.64 



Copper scale is readily re- 

 moved by scrubbing. 



27 



Cobalt acetate 



4.553 



0.293 



6.43 



Reaction not completed at 

 end of 10 days. 













28 



Cobalt acetate plus ammonium 

 hydroxide. 



2.669 



0.255 



9.56 



Action proceeds with efferves- 

 cence. 



29 



Chromium nitrate 



4.549 



0.467 



10.36 



72 hours required for com- 













pletion, coating is hard and 













adherent, and iron is attack- 













ed. 



* The iron base is attacked on continued immersion. 



