British Chemical Standard – bottles of 100g chips graded 180µm (85 mesh) for chemical analysis. Page 2 of 2 BCS-CRM No. 236/3 (ECRM 454-1) HEMATITE IRON NOTES ON METHODS USED SILICON All Analysts except No. 3 determined silicon gravimetrically. No. 1 used a nitro-sulphuric acid method (Dicks and Clarke, B.C.I.R.A. Journ., 1962, 10, 303) whereas Nos. 2, 4, 5, 6, 7 and 8 used the Standard method B.S. 1121 Part 10: 1967 which depends on double dehydration with perchloric acid. No. 3 used a titrimetric method based on the precipitation of potassium fluorosilicate which was filtered off, dissolved in hot water and titrated with standard alkali (Sneddon, Foundry Trade Journ., 1966, 120, 605). MANGANESE Analysts Nos. 1, 3, 4 and 5 determined manganese photometrically after oxidation with potassium periodate. No. 5 followed the procedure of the Standard method B.S. 1121: Part 23: 1951. Nos. 2, 6, 7 and 8 determined manganese titrimetrically by oxidation with persulphate/silver nitrate and titration with arsenite/nitrite solution (No. 2) or arsenite only (Nos. 6, 7 and 8). Analyst No. 3 also determined manganese titrimetrically after a zinc oxide separation and found 1.14%. PHOSPHORUS Analysts Nos. 1, 5, 7 and 8 determined phosphorus photometrically as phosphovanadomolybdic acid according to the Standard method B.S. 1121: Part 45: 1966. No. 2 determined phosphorus gravimetrically by precipitation as ammonium phosphomolybdate and conversion to lead molybdate according to the Standard method B.S. 1121 Part 9: 1948. Nos. 3, 4 and 6 determined phosphorus titrimetrically after precipitation as phosphomolybdate. Analysts Nos. 5 and 8 also determined phosphorus titrimetrically and found 0.047% and 0.046% respectively. SULPHUR Analysts Nos. 1, 3, 4, 7 and 8 determined sulphur by combustion, the sulphur gases being absorbed in hydrogen peroxide or silver nitrate solution and titrated with sodium borate ; Nos. 1, 3 and 7 used a stoichiometric method employing special porous cartridges for combustion of the samples (Green, B.C.I.R.A. Journ., 1963, 11, 76). Nos. 2, 5 and 6 determined sulphur gravimetrically. No. 2 carried out a chromatographic separation of the sulphur, as sulphuric acid, on an alumina column before precipitation as barium sulphate (Nydahl, Anal. Chem., 1954, 26, 580) whereas Nos. 5 and 6 used the Standard method B.S. 1121: Part 1: 1966. Analyst No. 2 also used the British Standard gravimetric method and found 0.066%. No. 4 also used a similar gravimetric method and found 0064%. No. 5 also used a combustion method and found 0.068%. TITANIUM Analyst No. 1 determined titanium photometrically by extraction of its thiocyanate trioctylphosphine oxide complex in cyclohexane. The other Analysts separated the titanium by precipitation with cupferron and determined it photometrically with hydrogen peroxide. Nos. 2, 3, 5, 6 and 7 followed the procedure of the Standard method B.S. 1121: Part 46: 1966 TOTAL CARBON Standard gravimetric method B.S. 1121: Part 11: 1967, Method 1. GRAPHITIC CARBON Standard gravimetric method B.S. 1121: Part 11: 1967, Method 2. NICKEL Photometric method using dimethylglyoxime (Analoid Method No. 44). ARSENIC Arsenic was precipitated with hypophosphite and determined iodimetrically. COPPER Photometric method using bis-cyclohexanone oxalyldihydrazone.

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