Photosensitive to Picture mold
Photosensitive. Sensitive to light or similar radiation.
Photostat. A photographic process for rapid duplication of maps, drawings, charts, and records on sensitized paper.
Photo synthesis. (Chern.) Process wehereby plants produce carbohydrates from water and carbon dioxide when the leaves of plants are exposed to sunlight.
Photovolatic. Providing a source of electric current under the influence of light or similar radiation.
Physical change (Phys.) A change by which the identity of the sub- . stance is not altered;.e.g., sawing a board into small pieces is a physical change.
Physical metallurgy. Has to do with the physical and chemical properties of metals being worked on as well as their action in service.
Physical pendulum. Any apparatus consisting of a body of possibly" irregular shape allowed to rotate freely about a horizontal axis on which it is pivoted.
Physics. The science which treats of . the constitution and properties of the matter.
Pi. (Math.) The ratio of the circumference of a circle to its diameter, or 3.1416. (Print.) Loose type matter badly mixed.
Piano wire. (Metal.) An exceptionally strong wire with tensile strength of from 300,000 to. 340,000 lb. per square inch. Its composition is as follows: carbon, 0.570; silicion, 0.090; sulphur, 0.011; phosphorus, 0.018; managanese, 0.425.
Pica. (Print.) A type size equivalent to twelve point. It is also the unit of length for rules, leads, slugs, etc.
Pick. (Textile) A filling thread. The rel;ltive value of cotton cloth is determined by the number of picks to the inch.
Picket. (Carp.) A narrow board used in making fences. It is often pointed at the top; sometimes called a pale or paling.
Picking of paper. (Print.) The pulling off of the surface of coated or enameled papers due to tacky ink.
Picking sort. (Print.) When a compositor is setting up a job and finds needed letters missing, he is compelled to pick; "sort" from other jobs to supply his own.
Pickle. The solution in which castings are dipped for cleansing. Dilute sulphuric acid is used for iron castings and iron plates; nitric acid for brass.
Pickling. (Fdry.) A process by which sand and foreign matter are removed from rough castings.
Picric acid. A monobasic acid (C6H2 (N02)3' OH) prepared by treating phenol-sui phonic acid with nitric acid. It forms yellow crystats. Used in the manufacture of explosives and to some extent in dyeing.
Pictorial. Representing as in a picture; containing or illustrated by pictures or drawings.
Picture mold. (Arch.) A molding at
Picture signal to pilot
tached to wall from which picture are hung.
Picture noise.Intereference signal causing spots of light and other irregular patterns on the reciever picture.
Picture signal. (Iel.) The electrical impulses which represent the video or picture elemetns being transmitted. (See SingaL)
Picture tube. (Tel.) A cathode-ray tube used to produce an image by variation of the beam intensity as the beam scans a raster. Piecework (Print.) Work paid for at the rate of so much per thousand ems.
Piecrust table. (Furn.) A table, usually round, having a raised, carved, or molded edge.
Poier. (Arch.) A mass of masonry supporting an arch, bridge, etc.
Pier glass. (Bldg.) A large mirror placed between two windows.
Pietra dura. (Arts.) Hard and fine stones as those used for inlay and the like.
Piezoelectricity. Electrification produced by pressure in particular directions on certain crystals.
Piezometer. A gauge for measuring the pressure of fluids or liquids.
Pig. (Metal.) Cast iron in the form of a bar ingot.
Pigeon-hole. Small open compartment, as in the upper portion of a roll-top desk, used as receptacle for letters, envolpes, etc.
Pig iron. (Metal.) The cast iron of commerce as it comes from the smelting furnace; usually in bars of about 100 lb.
'Pigment. (Chern, Colour, and p'rint.) That substance added to pamt or ink to give body and colour.
Pigskin. (Leather.) A leather of high quality and durability made from the skin of the domestic pig. Desirable for wallets, bill fords, cigarette cases, gloves, etc.
Ptgtail. (Elec.) A splice made by twisting togehter the bared ends of parallel conductors.
Pike pole. A pole tipped with a sharp metal point; used in supporting poles in an upright position during "planting" or removal.
Piklaster. (Arch.) A right-angled coIU!l'nar projection from a pier or wall.
Pile driver. A vertical framework provided with guides for carrying a weight which, after being elevated t6 the top of the framing, is allowed to fall, by force . of gravity, on the head of a pile.
Piling. (Engin.) Large timbers or poles driven into the ground or the bed of a stream to make a firm foundation.
Pillar. (Arch.) A column to support a structure.
Pillar file. (Shopwk.) Used on narrow work, cutting grooves, etc. Same general shape as a hand file but not as wide and is obtainable in any cut.
Pillow block. (Mech.) A bearing or support for a shaft.
Pilot. (Aero.) An operator of an aircraft. This term is applied regard less of the sex of the operator.
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