445
P YIl
PYR
vinces of Bigorre. Its mountains abound with game, lead, cop-per, iron, marble, jasper, and slate ; its valleys with corn, rye,millet, and flax. It is famous for fine horses. Tarbes is the ca-pital .
PYRETIC, [from a fever,] a medicine for a fever.
PYRETOLOGY, [moir©* and xvy©',] a treatise on fevers.
PYRIFORMIS, in anatomy. See Anatomy.
PYRITES, [from we;,] tire-stone, an inflammable substancecomposed of sulphur, saturated with metals. Thus there are manykinds of pyrites; as of gold, arsenic, iron, &c. It is also theprincipal ore of sulphur; particularly that called mhrtial pyrites,copperas-stone, or marcasite. This is very common, containing aquantity of sulphur in proportion to the iron; and, when tho-roughly inflamed, burns by itself. In the new chemical nomen-clature it is also called Sulphurated Oxide of Iron.
PYRMONT, a late county of Germany, in Westphalia ,bounded on the N. by that of Calenberg; E. by Wolfenbuttleand Calenburg ; S. by Wolfenbuttle ; and W. by Tip pc; 9 mileslong and 3 broad. It’is watered by the Emmer.
Pyrmont, the capital of the above county. It has a castle andmineral-waters, which are much esteemed. The Protestants havethe free exercise of their religion. It is seated on the confines ofthe duchv of Brunswick, 40 miles S. W. of Hanover. Lon. 9. 0 .E. Lat. .52. 0. N.
PYRN A. a town of Upper Saxony, upon Mount Sonnenstein ;10 miles S. E. of Dresden . Lon. 13. 56. E. Lat. 51.6. N.
PYROBOLI, [from tk;, fire, and to throw,] the fire-
works of the ancient Greeks.
PVROBOLY, and the art of making fire-works.
PYROLA, Winter-Green ; a genus of the decandria mono-gvnia class and order. Natural order, Bicornes. Calyx five-parted; petals five; capsule superior, five-celled, opening at thecorners, many-seeded; anthers with two pores. 1 here are sixspecies, natives of the north of Europe .
PYROLIGNOUS and PYROTARTAROUS ACIDS.When wood is distilled in close vessels, it always yields more orless of an acid juice : the same remark applies to the salt calledtartar. These liquids are distinguished by the name of pyrolig-nous and pyretartarous acids ; but they are now known to be onlythe acetic disguised by the presence of a peculiar oil.
PYROMANCY, divination by lire. See Di-
vination.
PYROMETER, Os and justsov,] an instrument for measuringthe expansion of bodies by heat. Muschenbroeck, who was the ori-ginal inventor of this machine, lias given a table of the expansionof the different metals in the same degree of heat. Havingprepared evlindric rods of iron, steel, copper, brass, tin, and lead,he exposed’ them first to the pyrometer with one flame in the mid-dle ; then with two flames; and successively to one with three,four, and live flames. But previous to this trial, lie took care tocool them equally, by exposing them some time upon the samestone, when it began to freeze, and Eahrenheit’s thermometer wasat 32°. The effects of which experiment are digested in the fol-lowing tabic, where the degrees of expansion are marked in partsequallo the - 5 , 4-73 part of an inch.
Expansion of
Steel
lirass
Tiii
Lead
By one flame.
80
85
89
no
153
155
By two flames placed to-getber.
117
123
115
220
274
By two flames 2 \ inchesdistant.
109
94
92
141
219
263
By three flames placedclose together.
142
168
193
275
. By four flames placedclose together.
211
270
370
361
By five flames.
230
310
310
377
'VOL, IV.—NO. 186,
Mr. Elicot found, upon a medium, that the expansion of brassof different metals as nearly of the same dimensions as possible, bythe same degree of heat, were as follow :
Gold, Silver, Brass, Copper, Iron, Steel, Lead ,
73 103 95 89 60 56 149.
The great difference between the expansions of iron and brass hasbeen applied with great success to remedy the irregularities inpendulums arising from heat. See Pendulum . The followingtable shews how much a foot in length of each metal grows longerby ail increase of beat, corresponding to 180° of Fahrenheit’s ther-mometer, or to the difference between freezing and boiling water,expressed in such parts of which the unit is equal to the to, 000 th
part of an inch.
J. White glass barometer-tube........ 100
2. Martial regulus of antimony. 130
3. Blistered steel.;. 138
4. Hard steel. 147
5. Iron...151
7. Copper hammered.204
8. Copper 8 parts, with tin one.218
9. Cast brass. 225
10. Brass 16 parts, with tin one.229
11. Brass-wire.........232
12. Speculum-metal.,...23'i
13. Spelter solder, viz. brass two parts, zinc one.247
14. Fine pewter...274
15. Grain-tin.298
16. Soft solder, lead two, tin one. 301
17. Zinc 8 parts, with tin one, a little hammered.323
18. Lead. 344
19. Zinc or spelter....353
20. Zinc hammered half an inch per foot.I..373
PYRAMUCOUS ACID, an acid obtained hi the distillation ofsugar and saccharine substances. It is now found to be the aceticacid holding empyreumatic oil in solution.
PYROPS, a mineral found in Bohemia , which was formerlydistinguished by the name of Bohemian garnet. It is never foundcrystallized, but only in round or angular fragments, usually small.Colour deep red, which passes to orange when the mineral is ex-posed to the sun. It is very hard-; the specific gravity is from3.7 to 3.9. Fracture conchoidal and very brilliant. It is com-posed of
40.00 silicaCS.50 alumina10.00 magnesia3.50 lime
16.50 oxide of iron0.25 oxide of manganese.
93.75
PYROPIIORUS, [from row, fire, aud prow, I bear,! in che-mistry, a compound substance, which takes fire on the’admbsionof the atmospheric air. It is prepared by exposing to heat in ani'-on-pot, three parts of alum, with one nart of flour ; the mixtureliquifies, and is to be stirred constantly till the whole becomesgrey, and easily reducible to powder while hot. The coarsepowder is put into a coated phial, so as nearly to fill it; the mouthof'the phial is stopped with a small plug of clay, and is placed in acrucible, and surrounded with sand up to the neck. The crucibleis heated to redness, until a blue flame appears at tfie mouth of thephial; when this has continued ten minutes, the crucible is re-moved from the fire, and the.phial, when sufficiently, cold, is ac-curately stopped. This substance inflames in atmospheric air ; ina moist atmosphere, the inflammation is much more speedy, and,in a dry air, it can scarcely take place. _ It burns also .very bril-liantly’in oxygen gas, in niveous gas, and in oxymuriatic acid gas;and is inflamed bv the sulphuric and nitric acids. See Alum.
PY’ROSTRIA, in botany, a genus of the tetrandria monogyniaclass and order. Calyx very small, four-toothed ; coro’da bell-shaped, five-cleft, tomentose in the throat; stamina four ; pistilsone; stigma capitate; pericarpium drupe, pear-shaped, inferior,small, eight-streaked ; nuts eight, one-seeded. There is but onespecies, viz. P. SaliCifolia, a native ot the island of Mauritius.
, 5 X PYROTECHNY.