pyritohedral 
or belonging to the class of hemihedral forms 
of which it is the type. 
It Is very curious that in the treatment with aqua regia 
Hi. cube and octahedron faces remain unattacked, while 
the acids exert a decided action upon the pyritohedral 
(pentagonal dodecahedral) faces, entirely destroying their 
power of reflecting light. Sri. Amer., N. 3., LX. 162. 
Pyrltohedral hemihedrism, in crystal. See hemihe- 
drimn. 
pyritohedron (pi-ri-tp-he'dron), w. [NL., < 
Gr. Trvpirt/f, pyrites, T iApa, 
a seat, base.] In crystal., 
a pentagonal dodecahedron 
(see dodecahedron); a solid 
contained by twelve penta- 
gons: a common form with 
pyrite, whence the name. It 
is the hemihedral form of the 
tetrahexahedron . 
... . . .,,,_... I yrilohc'lron. 
pyritology (pir-i-tol'o-ji),_n. 
[< Gr. mpirrif, pyrites, + -/oy/a, < teyetv, speak: 
see -ology.] 1 . Facts or information relating to 
pyrites. 2. A system of or treatise on blow- 
pipe analysis. 
pyritOUS (pir'i-tus), a. [< NL. pyrites + -ous.] 
Consisting of pyrites. 
pyre- (pi'ro- or pir'o-). [L., etc., < Gr. mpo-, 
combining form of Trvp, fire, = E. ./ire: see./iYf.] 
An element in many words of Greek origin or 
formation, meaning ' fire.' 
pyro-acetic (pi-ro-a-set'ik), a. [< Gr. Trip, fire, 
-r E. acetic.] Pertaining to or obtained from 
acetic acid when subjected to the action of heat . 
Pyre-acetic spirit. Same as acetone. 
pyro-acid (pi-ro-as'id), M. [< Gr. Trip, fire, + E. 
acid.] A product obtained by subjecting cer- 
tain organic acids to heat. Also pymcid. 
pyroballogy (pi-ro-bal'o-ji), . [< Gr. Trip, fire, 
+ /3d/Uf(V, throw, hurl (see ballixta), + -)*>) ia, 
< Zeyciv, speak: see -ology.] The art of throw- 
ing fire; the science of artillery, or a work on 
artillery. [Rare.] 
He was enabled, by the help of some marginal docu- 
ments, . . . together with Gobesius's military architec- 
ture suiApyrotiaUoi/y, translated from the Flemish, to form 
his discourse with passable perspicuity. 
Sterne, Tristram Shandy, li. :i. 
Pyrocephalus (pi-ro-sef'a-lus), . [NL. (J. 
Gould, 18IJ8), < Gr. 7ri>p, fire, + Kepi/./',, head.] 
A genus of Tyranuidx ; the vermilion flycatch- 
ers, which have in the male sex a full globular 
4876 
Pyrochroidae (pi-ro-kro'i-de), . pi. [NL. 
(Leach, 1817), < Pyrochroa + -idte.] A small 
family of heteromerous beetles of moderate 
size, with broad depressed bodies and elytra 
Vermilion Flycatcher ( fyroitftttttus mbincus], male. 
crest and the whole under parts flaming-red, 
the back, wings, and tail dusky-brown, p. rubi- 
neu is about sixinches long. A variety of this is found in 
Mexico and the southwestern parts of the United States. 
There are several others. 
pyrochlore (pi'ro-klor), M. [< Gr. Trvp, fire, + 
x'fjupoc,, yellowish-green: see clilorin.] A niobo- 
titanate of calcium, cerium, and other bases, 
occurring in isometric crystals, commonly oc- 
tahedrons, of a brownish color and resinous 
luster. It turns yellowish-green under the 
blowpipe, whence the name. 
Pyrochroa (pi-rok'ro-ii), . [NL. (Geoffrey, 
176L>), < Gr. rip, fire,'-! 1 ' %p6a, color.] A genus 
of heteromerous beetles, typical of the family 
Pyrocliroidx, and comprising about a dozen 
species, of which 2 are found in North Amer- 
ica, 1 in Japan, and the rest in Europe. P. 
ciii-cinea and P. niiVw.x are known as cardinal 
beetle*, from their red color. 
pyrochroid (pi-rok'ro-id), a. and . I. . Of or 
pertaining to the Pyrocliroiilie. 
II. H. A beetle of the family P 
t (anaJfMsir, a menilter of the family Pyrofltreidm. 
a, larva ; b, pupa ; f, beetle (female) : J. enlarged anal horns ; t. 
enlarged head of larva ; /. antenna of male beetle, magnified. (Line* 
show natural sizes of a, t, f.) 
broadening behind, and remarkable for their 
relative size. They live In all stages under the half- 
decayed bark of many trees. Five genera and about 20 
species are known, represented In Europe, Asia, North 
America, and Australia. Dendroidef canatlciixu is a com- 
mon North American member of this family. 
pyrochroite (pi-rok'ro-it). . [< Gr. Tri'p, fire, 
r xi'"", color, -I- -ife 2 .] Manganese hydrate, a 
mineral occurring in foliated forms with pearly 
luster, resembling brucite. It is white when 
fresh, but changes to bronze and black upon 
exposure. 
pyrocitric (pi-ro-sit'rik), . [<Gr. Trip, fire, + 
E. citric.] Obtained by subjecting citric acid 
to the action of heat. Pyrocltrtc acid. Same as 
citraconic acitl (which see, under citraconic). 
pyroclastic (pi-ro-klas'tik), . [< Gr. Trip, fire, 
+ K).(inn'ir, broken: see elastic.] Formed by 
volcanic agencies, or in the process of being 
erupted: applied to volcanic breccia or to any 
angular or comminuted material of igneous 
origin. 
It is asserted that there is an absence of masses of pyro- 
claxtic materials (tutfs and dust) such as we should expect 
to find around great volcanic centres. 
(Juart. Jour. Oeol. jc., XLV. 204. 
Pyroderinaet (pi-rod-e-n'ne), . pi. [NL., < /'//- 
rwlerux + -inie.] A subfamily named from the 
genus I'yroderufi. Sec Gymnoderinje. 
Pyrodems (pi-rod'e-rus), H. [NL. (G. R. Gray, 
1840), < Gr. Trip, fire, + Si-pi/, neck.] A genus 
of South American fruit-crows belonging to 
the subfamily (!i/miiodcriiitp, giving name to the 
Pyroderinee. Tiiere are 3 species, J'. xcutatux, 
P. orinoci-Hxix, and 7*. griinadcxiii*, inhabiting 
tropical parts of South America. 
pyrodin (pi'ro-din), M. [< Gr. Trptidi/c, like fire 
(< Triyi, tire. 4- Mof, form), + -in 2 .] An anti- 
pyretic, acetyl-phenyl hydrazine, CgH5N2H2C2 
HsO. Also called paenaeethydrattnt, 
pyro-electric (pi'rd-e-lek'trik), a. and . [< 
Gr. -ip, fire, + E. electric.'} I. a. Relating to 
pyro-electricity; having the property of becom- 
ing electropolar when heated, as certain crys- 
tals; thermo-electric. 
There are certain crystals which, while being heated or 
cooled, exhibit electrical chargesatcertain regions or poles. 
Crystals thus electrified by heating or cooling are said ti> 
be pyrihtlectric. S. P. Thompton, Elect, and Mag., p. 04. 
U. ii. A substance which becomes electrified 
when heated. 
pyro-electricity (pi'ro-e-lek-tris'i-ti), H. [< Gr. 
Tri-p, fire, + E. electricity.] That branch of elec- 
tricity which considers the production of a state 
of electrification in certain crystallized bodies 
by change of temperature alone. Thus, when a 
prismatic crystal of tourmalin is slightly heated, positive 
electricity is found to be developed at one extremity (called 
the analogoui pole) and negative at the other (the antiln- 
gou pole). If the crystal is cooled, similar properties are 
developed, but the poles are reversed. Many other crys- 
tals show the same property, especially t hose whose molec- 
ular structure differs at the opposite extremities of the 
same crystallographicaxisnike tourmalin) that is, which 
are hemimorphic or hemihedrnl. The unlike parts of a 
compound (twin) crystal of quartz become dissimilarly 
electrified by change of temperature. This can be well 
shown by shaking over a heated section of such a crystal a 
mixture of red lead and sulphur ; the former collects on 
the parts which are negatively, the hitter on those which 
are positively electritled. The phenomenon Is closely re- 
lated to the variations In stress which occur In the crystal 
when its temperature Is altered. Bv some writers pyro- 
electricity is used to include also the phenomena of thermo- 
electricity, which, however, are totally different in char- 
acter. 
pyrogallate (pi-ro-gal'at), n. [< Gr. irt>, fire, 
+ ET gallnte.~\ A salt of pyrogallic acid. 
pyrogallic (pi-ro-gal'ik), a. [< Gr. -vp, fire, + 
K. (/"'>'-'] Obtained from gallic acid by the 
action of heat : noting an acid, or more properly 
pyrolater 
a phenol (CqH 3 (OH) 3 ), which form* colorless 
crystalline plates or needles, soluble in water 
and poisonous. In the presence of alkali! It rapidly ab- 
sorbs oxygen, and it Is used In chemical proceMes lor that 
purpose. Pyrogallic acid rapidly reduce* salts of mercury, 
silver, and gold, precipitating the metals, and from Us 
property of reducing silver Baits Is one of the most effi- 
cient and most extensively used of photographic develop- 
ing agenU. 
pyrogen (pi'ro-jen), n. [< Gr. wi-p, fire, + ->frfo, 
producing: seo-f/f/i.] 1. Any substance which, 
introduced into the blood, causes pyrexia or 
fever. 2. The electric fluid. 
pyrogenesia (pi'ro-je-ne'si-ft), w. [NL.] Same 
as pyrogrnegi*. 
pyrogeriesis (pi-ro-jen'e-sis), n. [< Gr. iri>/j, fire, 
+ -jfviatc, generation : see genesis.] Production 
of fire or heat. 
pyrogenetic (pi'ro-je-net'ik), a. \_<pyrogenemn, 
after genetic.] Heat-producing. 
The actual rise of temperature that follows upon strip- 
ping In a cold atmosphere or upon first entering Into a cold 
bath is not one of the least curious phenomena of the reg- 
ulative function of the pyrogenetic mechanism. 
Arc. Cruite a/ the Corwin, 1881, p. 12. 
pyrogenic (pi-ro-jen'ik), a. [< Gr. trip, flre, + 
-yivt/f, producing : see -gen, -yenouit.] Producing 
fever. 
pyrogenous (pi-rej'e-nus), a. [< Gr. m>p, fire, 
+ -jei"}f, producing: see -ycnoun.] 1. Produ- 
cing or concerned in the production of fire or 
heat: as, pyroi/enou* action in the blood. 2. 
Produced by fire ; igneous. 
pyrognomic (pi-rog-nom'ik), . [< Gr. nvp, 
fire, + }vcj//ui', index, mark: see I/HOIHOH.] Ex- 
hibiting an incandescent glow when heated to 
a certain degree: specifically noting certain 
minerals. 
pyrognostic (pi-rog-nos'tik), . [< Gr. irvp, 
fire, + j itxrm'iif , knowing: see gnostic.] Per- 
taining to fire or heat: specifically noting those 
characters of a mineral which are observed by 
means of the blowpipe. 
pyre-gnostics (pi-rog-nos'tiks), n. [PI. ttfpyroy- 
noatic (see -j>*).] Those properties of a min- 
eral which it exhibits when neated, alone or 
with fluxes, in the blowpipe-flame or in the 
flame of a Bunsen burner, as the fusibility, 
intumescence, or other phenomena of fusion, 
flame-coloration, etc. 
pyrography (pi-rog'ra-fi), M. [< Gr. -arp, fire, 
+ tpaQetv, write.] A method of reproducing a 
design or an inscription on wood by the applica- 
tion underpressure of heated metallic plates or 
cylinders, the surfaces or peripheries of which 
bear dies or matrices in relief. 
pyrogravure (pi'ro-grfi-vur'), . [< Gr. Trip, 
fire, + F. yrarvre, engraving, < graver, grave : 
see oraw 1 .] A method of engraving on wood 
bv the use of a red-hot metallic point; also, a 
picture produced by this method. 
Puroyramre Is a new method of engraving In black, 
reddish brown, bister, etc., by the use of a red hot metal- 
lic point. Sei. Amer., N. 8., LVIII. 858. 
pyroheliometer (pl-ro-he-li-om'e-ter), H. Same 
as pyrlieliometer. 
Pyro'la (pir'o-lil), . [NL. (Tournefort, 1700), 
so called from the resemblance of the shining 
leaves to those of the pear-tree; prop. Pirola; 
dim. of L. pints, improp. pyrus, a pear-tree : see 
]'yruti.] 1. A genus of dicotyledonous plants 
of the order Kricaccte, the heath family, type 
of the tribe Pyrolcse, characterized by racemed 
flowers with five converging petals, ten sta- 
mens with peculiar four-celled inverted anthers 
opening by pores, and a capsule opening from 
tne base upward, with cobwebby margins. 
The 18 species are natives of the northern hemisphere, 
including 8 in the fnited States. They are smooth per- 
ennial herbs, sending out subterranean runners, and bear- 
ing radical or alternate long stalked evergreen leaves, 
commonly entire and rounded, ami an erect scape of bract- 
ed nodding flowers, which are white, yellowish, roae-col- 
ored, or purple. Several species are known in England 
and among American writers as mittergreen or/alre trinter- 
green. P. rotundtfulia, the larger wlntergrcen, Is the niont 
conspicuous species, a plant of both hemispheres, with 
thickish veiny round leaves, and commonly pure-white 
flowers, the stalk to 12 Inches high. It has been called 
Indian lettuce and cankrr -lettuce. P. eUiptiea, a smaller 
American plant with thin elliptical leaves, is called lAm 
leaf, a name also extended to tne genus. 
2. [/. r.] Anv plant of the above genus One- 
flowered pyrola, Xanetet grandijlom, a plant once In- 
cluded in the genus Pyrola. 
Pyrolaceae ( pir-o-la'se-e), n. pi. [NL. (Lind- 
ley, 1836), < Pyrola + -<tceie.] Same as Pyrolese. 
pyrolater (pi-rol'a-ter), n. [< pyrolatry (cf. 
idolater).] A fire-worshiper. [Rare.] 
The fires [were rejected) ... as having too near an 
analogy to the religion of the pyrolatort. 
SouOuy, Tbalaba, vllL, note. 
