Carotene and Ascorbic Acid in Foods 2. FRAPS, G. S., and A. R. KEMMERER. Purity and stability of commercial carotene. Indus. and Engin. Chem., News Ed. 19: 846-7. 1941. 3. FRENCH, R. B., and O. D. ABBOTT. Investigation of the vitamin C content of Florida fruits and vegetables. Effect of maturation and cold storage on the vitamin C potency of oranges and grapefruit. Jour. Nutr. 19: 223-32. 1940. 4. KIRK, MARY M., and DONALD K. TRESSLER. Determination of ascorbic acid. Electrometric titration method. Indus. and Engin. Chem., Analyt. Ed. 11: 322-3. 1939. 5. LEUKEL, W. A., and R. B. FRENCH. The physiological response of some grasses to different forms of nitrogen. Fla. Agr. Expt. Sta. Mim. Circ. Nov. 1941. 6. MCHENRY, EARLE W., and MURRAY GRAHAM. Observations on the Sestimations of ascorbic acid by titration. Biochem. Jour. 29: 2013-19. 1935. 7. MILLER, ELMER S. A precise method, with detailed calibration, for the determination of absorption coefficients; the quantitative measure- ment of the visible and ultraviolet absorption spectra of alpha carotene, beta carotene and lycopene. Plant Physiol. 12: 667-84. 1937. 8. MOORE, L. A., and RAY ELY. Extraction of carotene from plant mate- rial. A rapid quantitative method. Indus. and Engin. Chem., Analyt. Ed. 13: 600-2. 1941. 9. MUSULIN, R. B., and C. G. KING. Metaphosphoric acid in the extrac- tion and titration of vitamin C. Jour. Biol. Chem. 116: 409-13. 1936. 10. PETERSON, W. J., J. S. HUGHES and H. F. FREEMAN. Determination of carotene in forage. A modification of the Guilbert method. Indus. and Engin. Chem., Analyt. Ed. 9: 71-2. 1937. 11. SHARP, PAUL F., DAVID B. HAND and E. S. GUTHRIE. Quantitative determination of dissolved oxygen. Ascorbic acid oxidase method. Indus. and Engin. Chem., Analyt. Ed. 13: 595-7. 1941. 12. TAUBER, HENRY, I. S. KLEINER and D. MISHKIND. Ascorbic acid (vitamin C) oxidase. Jour. Biol. Chem. 110: 211-18. 1935. 13. TUBA, JULES, GEORGE HUNTER and HELEN RUTH STEELE. On the specificity of dye titration for ascorbic acid. Can. Jour. Res. 24B: 37-45: 1946.