16, 6 
Heise and Clemente: Corrosion of Iron 
441 
Table 1. — Effect of addition of potassium dichromate on the corrosion of 
iron in 0.5 N sulphuric acid. 
The corrosion of iron in 0.5 N sulphuric acid became pro- 
gressively greater with increasing additions of potassium di- 
chromate, until a maximum was reached. Further additions 
of potassium dichromate decreased the amount of corrosion, the 
iron becoming passive when between 18.75 and 25 grams of 
potassium dichromate were present in a liter of 0.5 N sulphuric 
acid. 
Very similar results are obtained with normal sulphuric acid 
as shown by the data in Tables 2 and 3. 
Table 2 . — Effect of addition of potassium dichronmte on the corrosion of 
iron in normal sulphuric acid. 
Experiment No. 
PotaB- 
Bium di- 
chromate 
added. 
Weight 
of iron. 
Loss due 
to corro- 
sion in 21 
hours. 
15 - 
Grams 
per liter. 
0.0 
Grams. 
14.624 
Grams. 
0. 166 
16 
2.6 
15. 597 
0. 687 
17 _ 
2.6 
14.953 
0. 563 
18.. _ . 
12.5 
16. 768 
2.219 
19 
12.5 
15. 216 
2. 225 
20 
26.0 
15. 489 
4. 166 
21 
25.0 
14.122 
4. 129 
22 
50.0 
15. 109 
3.334 
23 — 
60.0 
15. 424 
S.336 
24 
75.0 
14.678 
0.000 
26 
75.0 
14. 999 
0.000 
