PIGMENT 



1084 



PILATIO 



of the coal-tar colors. An adjective coloring-matter is 

 one which requires a mordant or mediating agent in 

 order to become insoluble upon the fiber. A mordant 

 is a substance which has an affinity for or which can 

 at least penetrate the tissue to be colored, and which 

 possesses also the property of combining with the 

 coloring-matter employed, and of forming with it an 

 insoluble compound within or about the fibers. Mor- 

 dants may be iron salts (copperas, ferrous acetate, 

 iron pyrolignite, ferric sulphate, and nitrates), nickel 

 (nickel-ammonium chlorid, nickel nitro-acetate), 

 chromium (chromium sulphate, fluorid, chlorate, potas- 

 sium di-cnromate and chromate), tin (stannous and 

 stannic chlorid, " pink salt," sodium stannate), man- 

 ganese (MnCl 2 , KMn0 4 ), lead, copper (nitrate), 

 antimony (tartar emetic), or tannin. Raising is the 

 process or method of intensifying colors by means of 

 mordants. Dunging is a term applied to the mordant- 

 ing of goods by passing them through a dung-bath, 

 which is a bath composed of water in which a small 

 proportion of cows' or pigs' dung, or some substitute 

 for it, has been dissolved, with a certain amount of 

 chalk to remove the acetic acid from the printed 

 material. A discharge is some compound, such as 

 the chlorid of lime, which has the property of bleach- 



Pigment-cells of Frog. A, Contracted ; B, C, Partially 

 relaxed pigment-cells. {From Stirling.) 



ing or taking away the color already communicated to 

 a fabric, by which means white patterns are produced 

 on colored grounds. A lake is a pigment formed by the 

 absorption of animal, vegetable, or coal-tar coloring-mat- 

 ter from an aqueous solution by means of metallic 

 bases. Application-colors. See Spirit-colors. Coal- 

 tar colors is a name given to a numerous class of 

 colors derived from coal-tar by various complex 

 chemic processes. Distemper, ox fresco, colors are colors 

 ground in water to a creamy consistency, with the ad- 

 dition of a sizing of glue or white of egg to make them 

 adhere to the surface to which they are applied. 

 They are generally used for decorating plastered 

 walls or ceilings. Graining-colors are colors ground 

 in linseed-oil with the addition of a small amount of 

 wax to prevent their spreading when manipulated 

 with a graining- comb to imitate the graining of 

 various woods. Japan-colors are those ground in the 

 medium called japan. An oil-color is a pigment of 

 any kind ground in linseed-oil or poppy-oil. Spirit- 

 colors (also called "spirits," or application-colors) are 

 certain colors obtained in calico-printing, so-called 

 from the use of "spirits," the technical name for the 

 acid solutions of tin, in applying the colors. Water- 



colors are pigments ground in water containing a 

 small amount of glue, glycerin, honey, or molasses, to 

 cause them to bind and adhere to the surface to 

 which they are applied. When pressed into molds 

 and dried, they are called cake-colors ; but when sold 

 in the form of stiff pastes, they are called moist colors. 

 Very many of the materials used for dyeing purposes 

 are extremely poisonous, and have been productive of 

 eczema and other skin-diseases, or even of systemic 

 poisoning. Recently the use of dyes as staining 

 reagents in bacteriologic, physiologic, and biologic 

 researches has assumed such marked importance that 

 it has been deemed advisable to introduce the following 

 conspectus (pages 1085 etseq.j, which contains the more 

 important pigments and dye-stuffs. P., Bile. See 

 under Bile. P., Blood, hemoglobin and its deriva- 

 tives. P., Brown. Same as Soudan Brown. P.- 

 cell, a cell specialized for the secretion or retention 

 of a pigment ; a chromatophore. P. -granule, a min- 

 ute, structureless mass of pigment. P., Hematogen- 

 ous, any pigment derived from the blood. Hemato- 

 genous pigments are hemoglobin, hematoidin, 

 hemosiderin ; the bile-pigments, which are indirectly 

 derived ffom the blood-pigment ; ferrous sulphid, 

 which stains the abdominal walls and the serous coat 

 of the abdominal organs after death, is also derived 

 from hemoglobin. P. -liver, a coloration of the 

 liver occurring in the course of malarial fevers, 

 and in the morbid condition of the blood described as 

 melanemia. The liver is also deeply pigmented in 

 pernicious anemia and in chronic valvular heart-disease, 

 with long-continued congestion of the organ. P., 

 Metabolic, a pigment formed by the metabolic action 

 of cells. Melanin is the type of metabolic pigments. 

 P. -molecule. Same as P. -granule. P., Respira- 

 tory, a pigment resulting from oxidation of the tissues, 

 or a pigment by means of which oxygen is absorbed. 

 Hemoglobin maybe considered a respiratory pigment. 

 P. -spot, in biology, a small mass of pigment in the 

 spores of certain plants and protozoans. P., Urinary, 

 urobilin, urochrome, uroerythrin, and others. P., 

 Uveal. See under Uvea. 



Pigmental, Pigmentary {pig-men' -tal, pig f -men-ta-re) 

 [pingere, to paint]. Pertaining to or containing pig- 

 ment. P. Atrophy, atrophy of adipose tissue with 

 deposit of pigment in the fat-cells. P. Layer, the 

 external layer of the retina. See Retina. P. Mole. 

 See Ncevtis pigmentosus. 



Pigmentation {pig-men-ta' -shun) [pingere, to paint]. 

 Deposition of or discoloration by pigment. See also 

 Chromatosis. 



Pigodidymus {pi - go - did'- im -us) [ nvyi/, buttock ; 

 didvfioq, double]. A double monster united at the 

 buttocks. 



Piitis {pi-i'-tis) [/w,pia; itic, inflammation]. In flam 

 mation of the pia ; leptomeningitis. 



Pike (pik) [ME., pike, a sharp point]. In biology, a 

 thorn or prickle. 



Pilar, Pilary {pi'-lar, pi'-lar-e) [pilaris; pilus, hair]. 

 Pertaining to the hair. 



Pilastered {pi-las' -terd) [pila, a small supplemental 

 pillar]. In anatomy, flanged so as to have a fluted 

 appearance ; arranged in pilasters or columns. P- 

 Femur, a condition observed in the femur of indi- 

 viduals' of certain races in which the backward 

 cavity of the femoral shaft is exaggerated, and the 

 aspera prominent. This exaggeration ol structure 

 causes the pilastered appearance. 



Pilastri {pi-las' -Ire) [pi. of Pilastrum, a small pillar]. 

 In biology, strong gelatinous columns placed between 

 the subgenital openings in Meduut* 



Pilatio {pi-la' -she-o) [pilus, hair]. A cranial fissure. 



