OSLER 



OSMUNDA 



Sir W. Osier, 

 British physician 



Russell 



Osier, SIB WILLIAM (1849-1919). 

 British physician. Born at Bond- 

 head, Canada, July 12, 1849, he 

 was educated 

 at McGill Uni- 

 versity, Lon- 

 don, Berlin, 

 and Vienna. 

 He was ap- 

 pointed pro- 

 fessor of 

 physiology at 

 McGill Uni- 

 versity, 1874, 

 of clinical 

 medicine at 

 Pennsylvania University, 1884, of 

 medicine at Johns Hopkins Univer- 

 sity 1889, and regius professor at 

 Oxford University, 1905. Created 

 a baronet in 1911, Sir . William 

 Osier wrote widely and authori- 

 tatively on nearly every aspect of 

 medicine. He died Dec. 29, 1919. 

 His books include Principles and 

 Practice of Medicine, 8th ed. 1912, 

 and A System of Medicine, 7 vols., 

 2nd ed. 1915. 



Oslo. Capital of Norway. The 

 name of Christiania (q.v.) was chang- 

 ed to Oslo as from Jan. 1, 1925. 



O sman OR OTHMAN 1 (1259- 

 1326). Founder of the Ottoman 

 empire. Born in Bithynia, he suc- 

 ceeded to the leadership of his 

 clan in 1288, and gradually con- 

 quered the surrounding Turkish 

 and Tartar tribes. Assuming the 

 title of sultan in 1299, he founded 

 the Osmanli or Ottoman dynasty. 

 See Ottoman ; Turkey. 



Osman Digna (1836-1900). 

 Dervish chieftain. A Hadendoa 

 slave dealer at Suakin, he was 

 made governor 

 1 of Eastern 

 j Sudan by the 

 | Mahdi (q.v.), 

 ] captured Sin- 

 kat and Tokar 

 in 1883, and 

 defeated Baker 

 Pasha's troops 

 at El Teb, Feb. 

 4, 1884, being 

 himself de- 

 feated there by General Graham, 

 Feb. 29, and also at Tamai, 

 March 13. Holding the country 

 round Suakin, he was a continual 

 menace to the Sudan. On the defeat 

 and death of 

 the Mahdi, 

 Osman was 

 killed in a 

 fray near 

 Tokar. 



Osmanieh. 

 Turkish order 

 o f chivalry, 

 in full the 

 Nishan -i - Os- 



manie or Qsmanieh, star oi 

 Order of the Turkish order 







Osman Digna, 

 Dervish chieftain 



Osman. It was instituted by Abdul 

 Aziz in 1861, and has four grades 

 The badge is a green star of seven 

 points with gold knobs, and be- 

 tween each are three golden rays. 

 The ribbon is of green watered silk 

 with red stripes near the edge. 



Osman Pasha (c. 1835-1900). 

 Turkish soldier. Born in Asia 

 Minor and educated for the army 

 at Constantinople, he fought in 

 the Crimea, the Lebanon, and 

 Crete, and won the rank of marshal 

 against the Serbians in 1876. His 

 fame, however, rests on his defence 

 of Plevna (q.v.). He was minister 

 of war, 1878-85, and died at Con- 

 stantinople, April 4, 1900. See 

 Russo-Turkish Wars. 



Osmanthus fragrans. Ever- 

 green shrub of the natural order 

 Oleaceae, native of Japan and 

 China. It has toothed, lance- 

 shaped, opposite leaves, and yel- 

 lowish-white, four-lobed, fragrant 

 flowers. The Chinese employ the 

 flowers to scent tea. 



Osmiridium. Alloy of the 

 rare metals osmium and iridium. 

 Characterised by great hardness 

 and durability, it is used for the 

 manufacture of fine instruments, 

 parts of ships' compasses, and for 

 watch pivots and other delicate 

 mechanical parts, and also for the 

 points of pocket pens. It is found 

 in Tasmania, where in 1920 the 

 output was valued at 67,987. 



Osmium. Rare metal dis- 

 covered in 1803 by Smithson Ten- 

 nent in samples of platinum ore. 

 Its atomic weight is 192 ; specific 

 gravity 22'0 ; melting point about 

 2,500 C. (4,532 Fah.); chemical 

 symbol, Os. It is bluish white in 

 colour with distinct lustre. It is 

 found, chiefly associated with 

 platinum, in the mines of Russia, 

 South America, California, and 

 the East Indies, in the form of 

 osmiridium or iridosmine. 



It occurs usually in grains, dis- 

 tinguished by their extreme hard- 

 ness and by the peculiar offensive 

 and poisonous fumes which they 

 give off when heated with potash. 

 The metal is most conveniently 

 recovered by heating osmiridium 

 in porcelain tubes to a white heat 

 in a current of air, when the oxide 

 of osmium sublimes over and is 

 collected as a powder, from which 

 the metal may be obtained by 

 reduction with hydrogen or car- 

 bon. The chief industrial use of 

 the metal is in the manufacture of 

 filaments for electric lamps. A salt 

 of the metal has been used for the 

 precipitation of bacterial organ- 

 isms in water. 



Osmosis (Gr. osmos, pushing, 

 impulsion). Name applied to 

 the diffusion of one liquid into an- 

 other, when they are separated by 



a permeable membrane. The force 

 impelling osmosis is known as 

 osmotic pressure. A piece of 

 bladder or parchment is a con- 

 venient membrane to employ in the 

 apparatus. The direction of the 

 osmosis varies according to the 

 composition of the liquids in the 

 inner and outer vessels. If the 

 osmosis be from the inner vessel to 

 the outer, it is called exosmosis, if in 

 the reverse direction endosmosis. 



I 



L 



i .. 



Osmanthus fragrans. Foliage and 

 flower of the Oriental shrub 



Osmosis plays an important part 

 in plant physiology and in chemis- 

 try. Elaborate investigations were 

 made by Pfeffer on the osmotic 

 pressure of sugar solutions through 

 films of copper ferrocyanide de- 

 posited on unglazed earthenware 

 pots. Afterwards van' tHoff estab- 

 lished the analogy between osmo- 

 tic pressure and gaseous pressure as 

 expressed by Avogadro's law. Van't 

 Hoff stated that the pressure is 

 due to the bombarding of the semi- 

 permeable membrane by the dis- 

 solved molecules trying to diffuse 

 into the solvent and bring about a 

 uniform concentration of the two 

 liquids. The osmotic pressure was 

 found to be identical with the 

 gaseous pressure which the weight 

 of dissolved substance would exert 

 at the same temperature, if it were 

 in the state of gas and occupied the 

 volume filled by the solution. 



Osmund (d. 1099). English 

 bishop and saint. Count of Seez in 

 Normandy, he accompanied the 

 Conqueror to England and was 

 created earl of Dorset. He is said to 

 have been also chancellor of Eng- 

 land. He embraced the religious 

 life, and in 1078 was made bishop 

 of Salisbury, where he built a cathe- 

 dral at Old Sarum about ten years 

 later. He wrote a Life of S. 

 Aldhelm, and had considerable skill 

 as a copyist and bookbinder. He 

 died in 1099, and was buried in 

 his own cathedral at Old Sarum. 

 Canonised in 1457, his remains were 

 removed to the new cathedral. 



Osmunda. Genus of ferns, the 

 most important of which is the 

 royal fern (q.v.). 



