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Germicides
616
CURRENT TOPICS.
[J. F. I.
Germicides.--In the Wiley Memorial Lecture, H. R. L. DOHME
(.Tour. Asso. Off. Agric. Chem., 1934, XVII, 19-28) reviews the history and value of germicides or disinfectants, agents which destroy microorganisms. The introduction and use of germicides followed the foundation of bacteriology by Koch and Pasteur and the development of the germ theory of disease. Among the earliest germicides were iodine, mercuric chloride, and phenol. Other substances that have found application in this field are lunar caustic (silver nitrate), colloidal metals, hypochlorites and chloramines, methenamine (hexamethylene tetramine), organic arsenical compounds (atoxyl, and arsphenamine and its derivatives), organic derivatives of mercury (mercurochrome, metaphen, methiolate, and mercurophen), certain dyes like acriflavine, and the alkyl resorcinols. However, "no germicide for the blood that is safe and has the approval of the medical profession is yet available." Research is now proceeding in this direction. J. S. H. Ascorbic Acid.--Many research workers consider that ascorbic acid, which is widely distributed in plants and animals, is a pure crystalline form of water-soluble C, the vitamin which protects from scurvy. It was formerly classed as a hexuronic acid, but its constitution has now been demonstrated by R. W. HERBERT, E. L. HIRST, E. G. V. PERCIVAL,R. J. W. REYNOLDS,AND F. SMITH (Joul'. Chem. Soc., 1933, I27O-129o). They used laevo ascorbic acid prepared from an animal source (adrenal glands) and from a plant source (paprica), found it to be related to the hexose sugar laevo gulose, to contain a double bond, to have the empirical formula CGHsOs, and the structural formula
CH2OH. CHOH. CH. COH = COH. CO. J. s. H. Nitrazine Yellow: A New Indicator.--HENRY WENKER (Ind. and Eng. Chem. Ind. Ed., 1934, XXVI, 35o) suggests the use of nitrazine yellow (2, 4-dinitrobenzene-azo-l-naphthol-3, 6-disulphonic acid) as an indicator. This compound dissolves in water to produce a red-brown solution, the color is bright yellow in acid solution, and a bright deep blue in alkaline solution. It is yellow at pH 6.0, pale yellow at pH 6.4, pale gray at pH 6.6, pale blue at pH 6.8, and blue at pH 7.0. J. S. H.
CURRENT TOPICS.
[J. F. I.
Germicides.--In the Wiley Memorial Lecture, H. R. L. DOHME
(.Tour. Asso. Off. Agric. Chem., 1934, XVII, 19-28) reviews the history and value of germicides or disinfectants, agents which destroy microorganisms. The introduction and use of germicides followed the foundation of bacteriology by Koch and Pasteur and the development of the germ theory of disease. Among the earliest germicides were iodine, mercuric chloride, and phenol. Other substances that have found application in this field are lunar caustic (silver nitrate), colloidal metals, hypochlorites and chloramines, methenamine (hexamethylene tetramine), organic arsenical compounds (atoxyl, and arsphenamine and its derivatives), organic derivatives of mercury (mercurochrome, metaphen, methiolate, and mercurophen), certain dyes like acriflavine, and the alkyl resorcinols. However, "no germicide for the blood that is safe and has the approval of the medical profession is yet available." Research is now proceeding in this direction. J. S. H. Ascorbic Acid.--Many research workers consider that ascorbic acid, which is widely distributed in plants and animals, is a pure crystalline form of water-soluble C, the vitamin which protects from scurvy. It was formerly classed as a hexuronic acid, but its constitution has now been demonstrated by R. W. HERBERT, E. L. HIRST, E. G. V. PERCIVAL,R. J. W. REYNOLDS,AND F. SMITH (Joul'. Chem. Soc., 1933, I27O-129o). They used laevo ascorbic acid prepared from an animal source (adrenal glands) and from a plant source (paprica), found it to be related to the hexose sugar laevo gulose, to contain a double bond, to have the empirical formula CGHsOs, and the structural formula
CH2OH. CHOH. CH. COH = COH. CO. J. s. H. Nitrazine Yellow: A New Indicator.--HENRY WENKER (Ind. and Eng. Chem. Ind. Ed., 1934, XXVI, 35o) suggests the use of nitrazine yellow (2, 4-dinitrobenzene-azo-l-naphthol-3, 6-disulphonic acid) as an indicator. This compound dissolves in water to produce a red-brown solution, the color is bright yellow in acid solution, and a bright deep blue in alkaline solution. It is yellow at pH 6.0, pale yellow at pH 6.4, pale gray at pH 6.6, pale blue at pH 6.8, and blue at pH 7.0. J. S. H.