1974. To Transfer Engravings to Paper

1974.     To Transfer Engravings to Paper. Place the engraving a few seconds over the vapor of iodine. Dip a slip of white paper in a weak solution of starch, and, when dry, in a weak solution of oil of vitriol. When again dry, lay a slip upon the engraving, and place both for a few minutes under a press. The engraving will be reproduced in all its delicacy and finish.

1975. To Print Engravings on Plaster

1975.    To Print Engravings on Plaster. Cover the engraved plate with ink, and polish its surface in the usual way; then put a wall of paper round it, and, when completed, pour in some finely-powdered plaster of Paris mixed in water; jerk the plate repeatedly, to allow the air bubbles to fly upwards, and let it stand 1 hour; then take the cast off the plate, and a very perfect impression will be the result.

1976. Hydrographic Paper

1976.    Hydrographic Paper. This is a name given to paper so prepared, that, when written upon with water, or some other colorless fluid, instead of ink, the characters will become visible.

1977. To Write Black Characters with Water

1977.      To Write Black Characters with Water. Thoroughly dry and reduce to a very fine powder a mixture of 4 parts nut-galls, and 1 part calcined sulphate of iron; rub it over the surface of the paper, then forcing it into the pores by powerful pressure; brush off the loose portion, and a pen dipped in water will write black.

1978. To Write Blue Characters with

1978.      To Write Blue Characters with. Water. Prepare the paper with a mixture of sesquisulphate of iron and ferrocy-anide of potassium, by the same method as the last receipt. Write with water as before, and the characters will appear blue.

1979. To Produce Brown Writing with Water

1979.    To Produce Brown Writing with Water. Instead of the sulphate of iron in the last receipt, use sulphate of copper ; and characters written with water will be reddish-brown.

1980. To Write Blue with a Colorless Fluid

1980.   To Write Blue with a Colorless Fluid. Wet the paper with a solution of ferrocyanide of potassium, and dry it again; write on it with a pen dipped in a solution of sesquisulphate of iron, and the writing will be blue.