No abstract

The tannin content of the barks of several Eastern Canadian conifers has been determined by standard methods in an attempt to assess their value as sources of tanning extracts.A more intensive study has been made of the extractable materials of white spruce bark. The chemical reactions of the extract from this bark show that the tannins therein are typical examples of the catechol or condensed group. Comparison of the ratio of tannin to non-tannins and the buffer index of this extract with the corresponding values for several commercial extracts indicates that the spruce extract would probably be fairly astringent. The titration curves of various fractions of the extract show some indications of the character of the non-tannin constituents.