PYROPE 



Pyrope. Blood-red variety of 

 garnet. Alternatively named 

 Bohemian garnet, it is found in 

 basic and eruptive rocks of the 

 serpentine and peridotite groups, 

 near Leipzig in Saxony, Bohemia, 

 in N. America, S. Africa, and near 

 Elie in Scotland. The stone is cut 

 as a gemstone, and though usually 

 of small size, large specimens have 

 been found. Those obtained in the 

 diamond fields of S. Africa are 

 known as Cape rubies, but they 

 are easily distinguished from 

 genuine rubies by their optical 

 properties. Pron. Py-rop. 



Pyrophorus. Substance which 

 takes fire on exposure to air. 

 Homberg (1662-1715) discpvered 

 that if he heated together in a tube 

 a mixture of lamp black, alum, and 

 flour, the charred mass caught fire 

 on being shaken out of the tube. 

 In the same way sulphides of pot- 

 assium, sodium, and lithium can 

 be prepared, which take fire on ex- 

 posure to air. Pyrophoric iron and 

 lead are also known, the latter 

 being made by charring lead tar- 

 trate. The pyrophoric iron used 

 in pocket lighters is an alloy of 

 iron and cerium. When struck or 

 rubbed this alloy gives off brilliant 

 sparks, which in pocket lighters are 

 made to ignite petrol vapour. 



Pyrotechnics (Gr. pyr, fire ; 

 techne, art). Scientific name for the 

 art of making fireworks (q.v.). 



Pyroxene. In mineralogy, the 

 name given to a group of silicates. 

 They are generally silicates of cal- 

 cium and magnesium, but may 

 also contain iron, aluminium, 

 chromium, manganese, zinc, etc. 

 The chief pyroxenes are augite, 

 an aluminium pyroxene; diopside, 

 a calcium manganese, white, grey, 

 yellow, or green in colour ; 

 hedenbergite, a calcium-iron pyro- 

 xene, black in colour, etc. The 

 pyroxenes are constituents of lime- 

 stone gneisses and igneous rocks, 

 particularly the latter, and some 

 are cut and polished as gem stones. 



Pyroxenite. In geology, an 

 igneous rock composed mainly of 

 varieties of pyroxene or amphibole. 

 The rock changes through weather- 

 ing into serpentine and talc. 



Pyroxylic spirit. Name for 

 crude methyl alcohol (q.v.). 



Pyroxylin. Alternative name 

 for gun-cotton (q.v.), and particu- 

 larly for the soluble variety used 

 for the preparation of collodion. 



Fyrrha. In Greek mythology, 

 wife of Deucalion, king of Phthia 

 in Thessaly. She and her husband 

 were the sole survivors of the great 

 flood which Zeus caused to over- 

 whelm the world. See Deucalion. 



Fyrrho (d. c. 275 B.C.). Greek 

 philosopher, founder of the first 

 school of Sceptics. He was a native 



of Elis, and accompanied Alexan- 

 der on his Indian campaigns. His 

 chief doctrines were : We can 

 know nothing of the real nature of 

 things, since the contrary of every- 

 thing that appears true may be 

 equally true ; we must therefore 

 withhold our judgement, and what- 

 ever happens, preserve our imper- 

 turbability of mind, which alone 

 brings happiness. Virtue is the 

 only thing that really matters ; 

 all external things are indifferent. 

 Pyrrhotite. In mineralogy, an 

 iron sulphide, generally mixed 

 with nickel. Yellow to red in 

 colour, with a metallic lustre, it is 

 found in some meteorites, with 

 magnetite, apatite, etc. 



Pyrrhus (318-272 B.C.). King 

 of Epirus, and one of the most 

 noted generals of ancient times. 

 His father 

 Aeacides hav- 

 ing been de- 

 posed, Pyrrhus 

 lived for some 

 years under the 

 pro tection of 

 an Illyrian 

 chief named 

 Glaucias.When 

 twelve years of 

 age, he was re- 

 stored to the 

 throne of his 

 father, but in 

 five years' 

 time, owing to 

 the intrigues of 

 Cassander 



Pyrrhus, 

 King of Epirus 



(17. v. ) he was again in exile. Taking 

 service under Antigonus, he found 

 himself a hostage of the Egyptian 

 king Ptolemy, when his patron had 

 been defeated at the battle of Ipsus, 

 301 B.C. Ptolemy assisted him 

 to recover his father's throne. 

 Consolidating his position as king 

 of Epirus, he began to endeavour 

 to extend his dominions, chiefly 

 at the expense of Macedonia, and 

 for a time was in actual possession 

 of the whole of that country. 



In 281 B.C. the inhabitants of 

 Tarentum in southern Italy, who 

 were then at war with Rome, 

 appealed to Pyrrhus for help, and 

 in the following year Pyrrhus 

 appeared in Italy with a con- 

 siderable army. The Romans were 

 defeated in two successive battles 

 at Heraclea, 280, and at Asculum, 

 279, but at such cost in human 

 life that the term " Pyrrhic vic- 

 tory " has passed into a proverb. 

 An invitation from the Sicilian 

 Greeks for assistance against the 

 Carthaginians took him over to 

 Sicily in 278, his lieutenant Milo 

 being left in command at Tarentum. 



The Sicilian campaign was at 

 first successful, but finding himself 

 very much handicapped by the 



PYTHAGORAS 



lack of unanimity among the 

 Sicilian cities, Pyrrhus in 276 re- 

 turned to Tarentum. His last 

 battle with the Romans took place 

 at Beneventum in 275, and resulted 

 in a severe defeat. His resources 

 failing, he returned to Epirus, but 

 before long he was again engaged 

 in new schemes of conquest. After 

 f ailing to take Sparta, he attacked 

 Argos, but in the street fighting in 

 that city he was killed by a tile 

 thrown from one of the houses by 

 an old woman. 



Pyrrol. Colourless oil with a 

 pleasant ethereal smell. It is ob- 

 tained by fractional distillation 

 from bone oil. When heated with 

 acids it is converted into pyrrol- 

 red. By the action of iodine on 

 potassium pyrrol, a substance 

 known as iodol is produced, which 

 is used as an antiseptic in place of 

 iodoform, over which it has the 

 advantage of freedom from smell. 



Pyrus. Genus of trees of the 

 natural order Rosaceae. See Apple. 



Pyruvic acid. Organic liquid 

 acid, with an odour resembling 

 meat extract and acetic acid. It is 

 also called pyroracemic acid, be- 

 cause it is produced by the dis- 

 tillation of racemic acid, an isomer 

 of tartaric acid. Lactic acid is 

 formed by the action of nascent 

 hydrogen on pyruvic acid. 



Pytchley. Famous English 

 hunt. It hunts a stretch of country 

 in Leicestershire and Northampton- 

 shire, from Market Harborough to 

 Northampton, the district being 

 about 20 m. from N. to S., and 

 25 from E. to W. The kennels are 

 at Brixworth. Founded about 

 1750, Earl Spencer was the first 

 master, and later earls have been 

 among its leading supporters. 

 From 1827-34, Squire Osbaldeston 

 was master of the pack. The 

 Woodland Pytchley is an offshoot 

 of the Pytchley, having been 

 established in 1874 to hunt the 

 part of the country N. and E. of 

 that now hunted by the older pack. 

 The kennels are at Brigstock. Both 

 packs are the property of the mem- 

 bers. See The Pytchley Hunt, H. 0. 

 Nethercote, 1888. Pron. Pltchley. 

 Pythagoras (b. c. 582 B.C.). 

 Greek philosopher. Born at Samos, 

 he settled at Crotona, in Italy, 

 about 529 B.C., 

 and there 

 founded a 

 school or 

 society, half- 

 religious, half- 

 phi 1 osophical. 

 His d i s ciples 

 were bound by 

 very strict 

 rules, under- 

 went acompre- 

 in gymnastics, 



Pythagoras, 

 Greek philosopher 



hensive training 



