Abstract
LONDON. Society of Public Analysts, October 6.—A. Chasten Chapman: On the presence of compounds of arsenic in marine crustaceans and shellfish. Marine crus-teans and shellfish have been found to contain from 10 to 174 parts of arsenic (as As2O3) per million of the wet edible portions. Native oysters contained from 5 to 10 parts, and Portuguese oysters from 33 to 70 parts per million. In fresh-water fish, shellfish and crustaceans, the amounts of arsenic ranged from only about 0.4 to 1.5 parts per million. The arsenic in the marine animals is therefore derived from the sea water. Potted and canned Crustacea and shellfish contained from 0.5 to 85 parts of arsenic per million. The arsenic in the urine of two experimental subjects was raised from the normal figure of about 1/200 grain per gallon to ½ grain in one case, and grain in the other, after a meal of lobster.—A. Chaston Chapman and H. Linden: On the presence of lead and other metallic impurities in marine crustaceans and shellfish. The following amounts of copper (parts per million of the dried edible portion) were found: lobster, 167; crab, 130; and whelks, 115. The amounts of lead ranged from 5 (whelk) to 25.6 (lobster). Native oysters contained from 12 to 400 parts and Portuguese oysters 10 to 307 parts of lead per million. Like the arsenic, these metallic impurities are probably derived from the sea water.—A. R. Tankard and D. J. T. Bagnall: The examination of fish for formaldehyde. Various kinds of fish gave a positive reaction in Schryvor's phenyl-hydrazine test, indicating the presence of 1 to 2 parts per million of formaldehyde. Since, however, trimethylamine (a common constituent of fish) can be readily oxidised to formaldehyde, a positive reaction does not necessarily indicate the presence of added formaldehyde. The reaction tends to be less marked when putrefaction of the fish has set in.—Karl Sandved: The potentiometric titration of tin with potassium bromate. The best results (error 0.5 per cent.) were obtained by oxidation of the stannous tin with antimony chloride or ferric chloride, and potentiometric titration of the reduction compound with potassium bromate. A method of determining tin in the presence of antimony has been devised, and the potentiometric titration of ferrous iron has been closely studied.—R. R. T. Young: The determination of nicotine in tobacco. Kellor's, Kissling's, and other methods have been critically examined. Accurate results are obtained by extracting the tobacco with a mixture of petroleum spirit, ether, and aqueous potash, shaking the ethereal extract with dilute (1: 1) alcohol containing cochineal, adding excess of hydrochloric acid to the separated aqueous layer, and titrating with standard sodium hydroxide. Ammonia is best determined by distillation after precipitation of the nicotine with iodine, but little ammonia, if any, was present in the tobaccos examined.
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Societies and Academies. Nature 118, 610–611 (1926). https://doi.org/10.1038/118610b0
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DOI: https://doi.org/10.1038/118610b0