mustard-plaister

The best mustard-plaister is made thus : take of mustard, in powder, two and a half parts, linseed-meal two and a half parts, boiling water ten parts.

...these Gissing 'mustard-plaisters' are still much coveted by collectors, and it is well worth rescuing from "the inequity of oblivion" examples of other Gissing novels published in the uniform series and house-styles of the 1890's and after.