PYRHELIOMETEK. 576 PYROLXJSITE. very complete review of iiyrhcliometers is given in the report on radiation by Jules VioUe, pub- lished in the report -of the meeting at Saint Petersburg. 1899, of the International Meterologi- cal Committee. PYB'IDINE, CiHjN. A powerful basic com- pound of carbon, hydrogen, and nitrogen. It is usuallv prepared on a commercial scale from coal- tar ; it combines with the sulphuric acid used in purifying the coal-tar hydrocarbons, and when the acid 'is neutralized with soda, a mixture of pyri- dine and several other bases (notably quinoline) separates out in the free state; from this mixture pyridine is isolated by fractional distillation, and it may then be obtained pure by transforming it into one of its salts and purifying the latter by repeated crvstallizations. Pure pyridine is a col- orless liquid that boils at 115° C. (2.39° F.) ami niav be readily identified by its peculiar odor. The derivatives of pyridine include many of the alkaloids (q.v.) ; nicotine, for example, is closely allied to it, and when subjected to a process of oxidation yields nicotinic acid, CoHjN.COOH, a com|ii)und evidently derived from pyridine by sub- stituting a carboxyl group (COOH) for one of its hydrogen atoms. Another important deriva- tive of pyridine is piperidinc. C,-,H,„XH, a color- less, powerfully basic liquid that boils at 100° C. (222.8° F. ) and nuiy be identified by its pepper- like odor. Piperidine may be obtained, on the one hand, from pyridine, by the action of nascent hydrogen: on the other hand, it may be prepared from the alkaloid piperine, a characteristic con- stituent of pepper, by the action of caustic pot- ash. The chemical constitution of pyridine and of pi])eridine is rejjresented, respectively, by the following graphic formulas: Hc; ."c^ CH H2C; Hc: XH N Pyridine. CHs H2C I CH? N H Piperidine. PYRITE (Lat. pjiritPS. from Gk. wvplrrit, R'mt, millstone, relating to fire, from TrCp, piir, fire). An iron disulphide (FeSj) that crystallizes in the isometric system, has a metallic lustre, and is of a brass-yellow color. It is videl_y dissemi- nated, occurring in rocks of all kinds and of all ages, sometimes in the form of grains disseminat- ed throughout the mass of a rock or along the line of contact between basic eruptives and sedi- mentaries; as irregular and sporadic and con- cretionary masses in sedimentary rocks and modern sands and gravels; in the form of true fissure veins; and as interbedded, often lenticu- lar masses, sometimes of immense size, lying conformably with the stratification of the in- closed rock. The origin of the mineral in the older crystalline rocks is frequently somewhat obscure, but in sedimentary rocks it is regarded as due to the precipitation of the included fer- ruginous matter by sulphureted and deoxidizing solutions produced by decomposing animal and vegetalde matter. When found on the surface the mineral is often considerably altered by oxidation and hydration, forming limonite. Py- rite is found in many localities, including Frei- berg, Saxony; Pribram, Bohemia; Schemnitz, Hungary: Langban, Sweden; Kongsberg, Nor- way ; Cornwall and Derbyshire, England ; and Peru. In the United States numerous localities where large crystals occur are known in Maine, New Hampshire, Vermont, Connecticut, New York, Pennsylvania, Virginia, North Carolina, Colorado, and California, The amount produced in the United States in 1901 was 234,- 825 long tons, valued at $1,024,440. The mineral finds its principal use in the manufacture of sul- phuric acid and ferrous sulphate (green vitriol). Small quantities are used in the manufacture of vermilion paints, and some varieties are cut into squares, ovals, and other shapes for u.se as set- tings for rings, scarf pins, trinkets, etc. Owing to its yellow' color, pyrite has been frequently called fool's gold, and many stories are told of the disappointment of miners, who, thinking they had found a fortune, were undeceived only when the mineral was submitted to experts. The name jtyriles is applied by Dana to a group of isometric sulphides and arsenides, in- cluding, besides that of iron, those of manganese, cobalt, nickel, etc. PYRKER, perlcer, .Iohann Ladislavs, von Felsil-Eur (1772-1847). An Austrian poet. He was born at Laugh, in Hungary, studied at Stuhl- weissenburg, where he had for teachers Anyos and Viriig, both classical scholars and poets in the vernacular, and, after many adventures, entered a Cistercian cloister at Lilienfeld. There he showed much executive ability and rose rap- idly. He was made Archljishop of Erlau in 1827, and in this office did many good works. His poetry is ambitious epic for the most part, full "of patriotism and piety. Tunisias (1819) told of the conquest of Tunis by Charles V. : Rudolf von HaUhurg ( 1824) sang the glorious deeds of Rudolf of Hapsburg; and the Pcrlcn der hciligen Vor::eit (1821), Leyetiden der Eeiligpn (1842), and Bilder aus dem Lehen Jesu und der Apostrl (1843) are biblical and ecclesiastical. But if his epic is flat in its attempts at Homeric simplicity, it cannot be denied that there is the true 'lyric cry' in his Liedcr der l^ehnsiickt mich den Alpen (1845). Pyrker's collected works in three volumes ap]ieared 1853-56. Consult : Sauer's critique in Allficmeine Deutsche Biographic, vol. xxvi.. pp. 790-94. PYRMONT, per'mont. A small town in the Principality of Waldeck, Western Germany, 15 miles northeast of Detmold. It is celebrated for its mineral springs, which were formerly among the most famous in Europe, and are still visited liy over 18,000 patients annually. Perma- nent population, in 1900, 1483. PYRMONT. A former principality of Ger- many, united with Waldeck (q.v.). PYR'OLIG'NEOUS ACID, See Acetic Acid. PYR'OLU'SITE ( from Gk, irvp, pyr, fire + ovfi% /oK.SiS, bath, from oi(i.v, (ohtih, to wash). A mineral manganese dioxide that crystallizes in the orthorhombic sy.stem and has a metallic lus- tre and a dark iron-black or steel-gray color. Manganese oxides are believed to have been formed from the decomposition of preexi^tmg manganiferous silicate constituents of the nhler crystalline rocks and the subsequent decomposi- tion of the oxides in secondary strata. Pyrolusite
