A text-book on chemistry. For the use of schools and colleges (1866)
Draper, Henry, 1837-1882 · New York, Harper & brothers · leaf 469
te of iron, with anequal weight of gum arabic, and a few drops of crea-sote. Let the mixture digest for two or three weeks,with occasional agitation, then decant. Tannic acidforms insoluble compounds with starch, gelatine, andother organic bodies, that with gelatine being of con-siderable interest:… … GALLIC ACID. 457 characteristic precipitate it gives with iron, it is usedas a test for that metal, which must, however, be in thestate of peroxide, as the protosalts are unacted upon.The gradual darkening of pale writing inks is due tothe slow oxidation of the iron they contain. Tannin isvery…
Chemistry · Physics
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