Pounce

Powdered gum juniper is used under this name, for preparing parchment for writing on. For liquid pounce, see Ink, Marking.

Poudre Clarifiante

Beat together the whites and yolks of eggs, dry them with a very gentle heat, and reduce to powder. For clarifying Mines and syrups.

Powders

See Tooth Powders, and Hair Powders, under Cosmetics; Scent Powders, under Perfumery, etc.

Preservative Liquids

See Anatomical Subjects, and Animal Substances, to Preserve.

Prussiate of Potash (Yellow)

What is known in commerce by this name is the ferro-prussiate of potash, or ferrocyanide of potassium. It is prepared by fusing in an egg-shaped iron pot a mixture of 2 parts of pearlash and 5 parts of dry animal matters, such as horns, hoofs, tallow-chandler's greaves, etc., till fetid vapours cease to be produced. Iron tilings are sometimes added, but usually the iron necessary to the formation of this salt is derived from the iron pots and stirrers. The fused mass (prussiate cake) is allowed to cool, dissolved in warm water, and the clear filtered or decanted solution evaporated, that crystals may form. These are dissolved in hot water, and the solution allowed to cool very slowly, that large crystals may form.

Soluble Prussian Blue

Add a solution of proto-sulphate of iron to a solution of prussiate of potash, and expose the precipitate to the air till it becomes blue, and wash it till the soluble salts are washed away. By continuing the washing, the blue itself dissolves, forming a deep blue solution, which may be evaporated without decomposition. Or add a solution of persulphate of iron to a solution of ferro-prussiate of potash, keeping the latter in excess; wash the precipitate until it begins to dissolve, and dry it. See Ink, Reade's Patent Blue, for another method.

Rat and Mice Poisons

[Such as contain arsenic are placed first, and afterwards several compounds which have been introduced as substitutes for that mineral, which has proved so destructive of human life. According to a recent Act of Parliament, this dangerous compound can only be purchased in wholesale quantities. Among other precautions taken to prevent accident, it is provided that it be mixed with colouring matters, such as soot and indigo, in order to prevent its being taken by mistake, or to ensure detection if designedly administered.]

Rennet

The stomach of a calf, washed, salted, and dried.

Rennet Liquid

Essence of Rennet. Fresh rennet 12 oz., salt 2 oz., proof spirit 2 oz., white wine a quart; digest for 24 hours and strain. A quart of milk requires 2 or 3 teaspoonfuls. Wislin directs, 10 parts of a calf's stomach, salt 3 parts. The membrane of the stomach is to be cut with scissors, and kneaded with the salt and with the rennet found in the interior of that organ; the whole left in a cool place in an earthen pot till the cheesy odour is replaced by the proper odour of rennet, which will be in 1 or 2 months. Then add 16 parts of water and 1 of spirit. Filter and colour with burnt sugar.