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Sympathetic Laks

Process I.--Write with a solution of sulphate of iron,--the writing will be invisible. Dip a feather in an infusion of nutgalls (water in which pulverised nutgalls have been steeped,) and the writing will become black. Process 2.--Write with a dilute infusion of galls,--it will be invisible. Dip a feather in a solution of sulphate of iron, and moisten the paper with it and the writing will become black.

Process I.--Write with a solution of sub-carbonate of potass; wet this writing with a solution of sulphate of iron,--it will take a deep yellow colour. Process 4.--Write with a solution of sulphate of copper,--no writing will be visible. Wash the paper with a solution of prussiate of potass,--the writing will then get a reddish brown colour.

Process 5.--Write with diluted nitrate of silver, and let the writing dry in the dark--it will be invisible; but expose the paper to the rays of the sun, and the writing will become black.