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duplicate per %hour day. This can probably be increased by using a longer filtration setup and more hot plates. Finally, because of the high precision demanded the method requires rigorous attention throughout. The operator should thoroughly familiarize himself with the titration until he experiences no difficulty obtaining good checks in the standardization. Burets and pipets must be completely free from any contaminants which might result in the improper delivery of liquids. If srunples are run daily, it is advisable to check the thiosulfate normality daily. LITERATURE CITED (1) Aborn, R. H., ilnd Brown, R. R., IND. END.CHEM..ANAL.Eo.. 1. 26 (1929). (2) Am. SOC.Testing M&tterials.D526-42 (October 1942).
(3) Calingsert, G, and Gambrill. C. M.,IND. ENO.CHEM., ANAL. ED.,11,324 (1939). (4) Cstlin. L. J., and S t m e t t , J. E., Refiner Natural Gas Mfr., 9, 155 (1930). (5) Clark, G. L., andsmith, H. A,. J . Phys. Cfiem.. 33, 659 (1929). (6) Edgar, G., and Cslingaert, G.. IND.ENG.CHEM.,ANAL.ED., 1. 221 (1929). (7) Foglino, N.,and Marciante. A,, Ann. ohim. applicata, 32. 245
ilr,"", -=*, . (8) Frediani, H. A,, and Bass. L. A,, Oil Gas. J.. 39, No. 20, 51 (December 1940). (9) Gonick. H., and Milano, J. J., IND.ENC.CHEM., ANAL.ED..16, 4 (1944). (10) Lykken, L.,Treseder, R. S., Tuemmler. F. D., and Zahn, V.. Ibid.. 17, 353 (1945). (11) Sohwsrtn, L.,Ib
