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in water, of such strength, that the liquor concreted intoa gelly before it was quite cold: with this gelly, kept fluidby sufficient heat, I mixed some ivory black: charactersdrawn with this mixture on paper bore rubbing muchbetter than the others, but were discharged withoutmuch difficulty by a wet pencil.

It was now suspected, that the colour could not be suf-ficiently fixed on paper without an oily cement. As oilsthemselves are made miscible with watery fluids by theintervention of gum, I mixed some of the softer printersvarnish, already described, with about half its weightof a thick mucilage of gum arabic, working them welltogether in a mortar, till they united into a smooth uni-form mass: this was beaten with lamp black, and somewater added by little and little, the rubbing being con-tinued, till the mixture was diluted to a due consistencefor writing. It wrote freely, and of a full brownifh-blackcolour: the characters could not be discharged by tub-ing, but water Washed them out, though not near soreadily as any of the foregoing. Instead of the printersvarnish or boiled oil, I mixed raw linseed oil in the samemanner with mucilage and lamp black, and on dilutingthe mixture with water, obtained an ink not greatly dif-ferent from the other.

Though these oily mixtures answered better than those?with simple gums of glues, it was apprehended that theirbeing dischargeable by water would render them unfit forthe purposes intended. The only way of obviating thisimperfection appeared to be, by using a paper, whichshould admit the black liquid to sink a little into its sub*stance. Accordingly I took some of the more sinkingkinds of paper, arid common paper made damp as forprinting; and had the satisfaction to find, that neither theoily nor the simple gummy mixtures spread upon them so

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