Summary
A study has been made of the colouring matter extracted from liquorice root and of some of the possible causes of variation in colour of liquid extract of liquorice B.P. It has been shown that the colour variation occurring in samples of extract prepared according to the official instructions may result from the standardisation of the preparation on its content of total water-soluble extractive. The effect of changes in pH value on the colour of liquid extract of liquorice has also been investigated. The authors wish to thank Miss S. M. Stokes for assistance in carrying out the practical work, and the Directors of The British Drug Houses, Ltd., for permission to publish this paper.