16,5 Heise and Clemente: Corrosion of Iron 441 
TABLE 1—Effect of addition of potassiwm dichromate on the corrosion of 
iron in 0.5 N sulphuric acid. 
Potas- Loss du 
Expittnent No. sium di-| Weight to corro- 
chromate} of iron. |sion in 20 
added. hours. 
Grams 
per liter.| Grams. | Grams. 
Wk ee hc Thea Ohad eset suse wa 0.0 15. 055 0. 070 
PSE ESR Ri ee Dae or ah le ar HARE COT s PApOOR © SNL eT wep RO RA OEE eta pe 0.0 15. 884 0.078 
Rt So FI DESO GR Lo REE Wily Ue ees ee Oe ee ERC RE Re oes ere era 2.5 14, 231 0.517 
hints bug Geccuk’. sik Scahhi cate ees. asta Ss Caan eas bEbet 2.5 14.176 0.474 
_ SESE ae LOE eRe nee ree ce eee PR EPEC Me? ene EO rye eae 6.25 15.410) . 1.163 
Re ee ee 6.25} 15.301| 1.125 
Fe NGM eiiane cdoiiis kgenckegh dita as) Ae nak sien bans tha elocnaees 12.5 13, 985 2.071 
__ ee a eee pedand po gacutc a ete reg ae wep vente 12.5 15.756 | 2.109 
engine ee ios wreaked oe a ald ace ee es a oe eee Sa ee 18. 75 15. 007 1. 775 
5 RED TESA RRS Abe tah - de a on eo og Aig PSE iat ERE 18. 75 13. 948 1. 726 
th” Se OOP ee Ra RCREROMENEE ST TE KES CM ETE CeIn t ce MEAT PAE 25.0 15. 457 0. 002 
Te ations Bisiiite d Siic bide < wenglabed a cece lcagqdan ce Riciee ete 25.0 15. 462 0. 002 
EE ECE AEES Vic Nae ENR Pe ee aes SEM Ee Meee ee 87.5 15.774 0. 001 
ag ni Ss RSME jh SR i I gs a A ag eam lie 87.5 15.101 0. 003 
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 dichromate on the corrosion of 
iron in normal sulphuric acid. 
a r 
Potas- | ; Loss due 
| Experiment No, aoe ea bate nig sion im 2A 
added. hours. 
I. 
Grams | 
per liter.| Grams. | Grams. 
MP end cic att oe ee a eed 0.0} 14.624| 0.156 
hg UNIT CE ASE BAGS PRL REN CRITE Ue SIE eee rw ie ee ae | 2.6 | 15.597 | 0.687 
i i BT a a al 2.5 14. 953 0, 563 
iO SRRSASSA Seis ar es a gear mer by, aa eae NG TR 12.5) 15.768) 2,219 
tei ee ee 12.5 | 15.216 | . 2.225 
a ee eS ee Oe pet rir 25.0| 15.489/ 4.166 
te Ee ee | Ean eee eae oe gi 25.0; 14.122| 4,129 
RSE oP Pa Se St ig eles itaia Gane ne eR et 50.0} 15.109| 3,334 
ES Ir A ca act ga Ue DN cds GOGO TEAR OR alto 50.0 | 15.424 / 3.336 
Wee HB GoTi BU pi io: ds tt. eS ee ' 75.0 14.578; 9.000 
sce i SOS gag ating Sa te cae Page eines Se | 75.0) 14.999) 0.000 
