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much cf the copper was dissolved, that the writings be-came in a short time as ill-coloured, as if the ink hadbeen of the worst: kind. It is pretty singular that thevitriolic acid, in its separation from the iron, should dis-solve a body, on which otherwise, in so dilute a state, itdoes not seem to have any action. Leaden vessels are alsoobserved to be corroded by ink, and debase its colour;and probably, except the materials of which ink itself iscomposed, all the other bodies, that the vitriolic acidis capable of dissolving, will be found injurious to ink.

II. Compostmi of ink, deduced from the experinmits.

The foregoing experiments point out, for the best pro-portions of the ingredients, one part of green vitriol, oneof powdered logwood, and three of powdered galls. Thebest menstuum appears to be vinegar or white wine,though for common use water will suffice. The quantityof menstruum admits of great latitude : to make an inkof a full body of colour, it should not exceed a quart, orat most three pints, to three ounces of the galls, and oneounce of each of the other two ingredients. The pro-portion of gum may be varied at discretion, accordingas the ink is wanted to be more or less glossy or shining,or as the nature of the paper may require the fluidto be well gummed to prevent its sinking: half anounce to a pint is in most cafes sufficient; though themore gum we can employ, consistently with due free-dom of writing, it is probable that the ink will be themore durable.

The ingredients may be all put together at once, in anyconvenient vessel, and well shaken four or five times aday. In ten or twelve days, and sooner if set in a warmplace, the ink will be fit for use; though both its colourand durability will be improved by standing longer on

the