This research was suggested to me by different experiences with sodium benzoate when taken by mouth in the following ways: A. Pure (1) as crystalline salt, or (2) in aqueous solution. B. In neutral or alkaline solutions, or in mixtures rich in fat, carbohydrate or protein, e. g., milk. C. With vegetable or fruit acids (1) hot, as in tomato soup, or (2) cold, as in canned plums, oranges, lemons, etc. D. In beverages containing high percentages of organic acids, e. g., cider, lemonade, grape juice, wine, etc. E. In mixtures containing inorganic acids, e. g., artificial gastric juice.
Brunton has studied the effects of benzoic acid on enzymes and bacteria. The strong inhibiting effect of this substance on their activity is in striking contrast to the slight effect of sodium benzoate. Doepner has shown that fairly large quantities of sodium benzoate (2 per cent.) did not prevent the development of Proteus vulgaris and, in strengths equal to 0.5 per cent., only slightly retarded the development of B. euteritidis, B. fluorescens and B. coli. Fleck found that benzoic acid in concentrations equal to 0.6-0.7 per cent. caused marked inhibition of yeast fermentation and that the inhibiting action was markedly decreased by the amount of protein present. Lehman observed that meat extract putrefies in the presence of 1 to 2 per cent, of sodium benzoate, but less benzoic acid acts more strongly antiputrefactive when the reaction of the medium is markedly acid. The action of sodium benzoate under markedly acid conditions is the same as the action of benzoic acid. Under such conditions the action of the benzoate diminishes with decrease of acidity. Chassevant and Garnier found that 1.4 gram of benzoic acid per kilo was fatal to guinea pigs in five to seven hours; larger doses (2 grams per kilo) did not necessarily kill sooner.
