The lignin fraction of animal feeding‐stuffs. I.—preliminary examination of lignin determination procedures

The procedures commonly employed for the determination of lignin in plant materials used as animal feeding‐stuffs are reviewed with particular reference to the possible sources of error. A study of the reproducibility of each stage in the determination of lignin by a method employing 72% sulphuric acid is reported, and it is concluded that the variability of the final lignin yields is partly due to the presence of alcohol‐soluble substances not completely removed before the main treatment with 72% sulphuric acid. The need is indicated for further investigation of various ‘humin’ precipitates obtained during lignin determination.