PETROLEUM JELLIES: See Lubricants.
PETROLEUM SOAP: See Soap.
PEWTER: See Alloys.
PEWTER, TO CLEAN: See Cleaning Preparations and Methods.
PEWTER, AGEING:
If it is desired to impart to modern articles of pewter the appearance of antique objects, plunge the pieces for several moments into a solution of alum to which several drops of hydrochloric or sulphuric acid have been added.
PICTURES, GLOW.
These can be easily produced by drawing the outlines of a picture, writing, etc., on a piece of white paper with a solution of 40 parts of saltpeter and 20 parts of gum arabic in 40 parts of warm water, using a writing pen for this purpose. All the lines must connect and one of them {523} must run to the edge of the paper, where it should be marked with a fine lead-pencil line. When a burning match is held to this spot, the line immediately glows on, spreading over the whole design, and the design formerly invisible finally appears entirely singed. This little trick is not dangerous.
PHOSPHATE SUBSTITUTE.
An artificial phosphate is thus prepared: Melt in an oven a mixture of 100 parts of phosphorite, ground coarsely, 70 parts of acid sulphate of soda; 20 parts of carbonate of lime; 22 parts of sand, and 607 parts of charcoal. Run the molten matter into a receiver filled with water; on cooling it will become granular. Rake out the granular mass from the water, and after drying, grind to a fine powder. The phosphate can be kept for a long time without losing its quality, for it is neither caustic nor hygroscopic. Wagner has, in collaboration with Dorsch, conducted fertilizing experiments for determining its value, as compared with superphosphate or with Thomas slag. The phosphate decomposes more rapidly in the soil than Thomas slag, and so far as the experiments have gone, it appears that the phosphoric acid of the new phosphate exercises almost as rapid an action as the phosphoric acid of the superphosphate soluble in water.