Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/725

Rh M O L M M 697 thus distributed over an area measuring about 450 miles from east to Avest, and about 800 from north to south, and include (1) the Moluccas proper or Ternate group, of which Jilolo is the largest and Ternate the capital ; (2) the Bat- chian, Obi, and Sula groups ; (3) the Ambon or Amboyna group, of which Ceram (Serang) and Buru are the largest ; (4) the Banda Islands (the spice or nutmeg islands par excellence}, of which Lantoir or Great Banda is the largest, and Neira politically the most important ; (5) the south eastern islands, comprising Tenimber or Timor -Laut, Larat, &amp;lt;fcc. ; (6) the Kei Islands and the Aru Islands, of which the former are sometimes attached to the south eastern group ; and (7) the south-western islands or the Babber, Sermatta, Letti, Wetter, Roma, and Damme groups. At the close of the 16th century this part of the archi pelago was divided among four rulers settled at Ternate, Tidore, Jilolo, and Batchian. The northern portion be longs to the Dutch residentship of Ternate, the southern portion to that of Amboyna. The name Moluccas seems to be probably derived from the Arabic for &quot;king.&quot; Argensola (1609) uses the forms islas Malucas, Maluco, and el Maluco; Coronel (1623), islas del Moluco ; and Camoens, Maluco. Compare the articles on INDIAN ARCHIPELAGO, ARU ISLANDS, JILOLO, TERNATE, &c., and J. J. &amp;lt;le Hollander, Handleiding bij de, Bcocfening dcr Land- en Volkenkunde von Ned. Oost. Indie, Breda, 1877 and 1882. MOLYBDENUM, one of the rarer metallic elements (symbol for atomic weight, Mo = 96; H = l), occurs in nature chiefly in the two forms of Yellow Lead Ore (PbOMoOg) and Molybdenite (MoS 2 ). The latter mineral is very similar in appearance and in mechanical properties to graphite or black lead, and, in fact, was long confounded with it chemically, until Scheele in 1778 and 1779 proved their difference by showing that only the mineral now called molybdenite yields a white earth on oxidation. The metallic radical of the earth, after its discovery by Hjelm, was called molybdenum, from )u,o&amp;gt;a&amp;gt;/38os, lead. By heating molybdenite in a combustion tube in a current of air, we obtain the trioxide Mo0 3 (molybdic acid) as a white crystalline sublimate. This substance, when heated to redness in close vessels, fuses without much volatilization into a yellow liquid, which, on cooling, freezes into a crystalline radiated mass of 4 39 specific gravity. It dissolves in 500 parts of cold, and in 960 of hot water. It dissolves readily in aqueous ammonia or alkalies, form ing molybdates. Like silica, it combines with bases in a great variety of proportions. Of these many salts, an ammonia salt of the composition 3(NH 4 ) 2 0. 7Mo0 3 + 4HoO (known in laboratory parlance simply as molybdate of ammonia) is the most important, affording, as it does, the most delicate, characteristic, and widely applicable precipitant for ortho-phosphoric acid. To detect phos phoric acid in any substance soluble in water or nitric acid, add first to a solution of molybdate of ammonia an excess of nitric acid, and then (not too much) of the nitric solution of the phosphate, and keep the mixture at 40 C. ; the whole of the phosphoric acid gradually separates out in the shape of a canary-yellow crystalline precipitate of &quot; phospho-molyldatc of ammonia&quot; of the composition 24Mo0 3 . P,0 5 . 3(NH 4 ) 8 I, i fiH O + 24Mo0 3 . P.,0 5 . 2(NH 4 ) 2 . H 2 / + )H 2 (according to Gibbs), which is insoluble in the reagent, even in the presence of dilute nitric acid, but soluble in excess of phosphoric acid. By treatment of this complex ammonia salt with aqua regia we can eliminate its acid 24Mo0 3. P._&amp;gt;0 5. 3H..O as a substance soluble in water and crystallizing from &quot;this solution with 59 molecules of water. This phospho-molybdic acid plays a great part in chemical toxi cology, being a generically characteristic precipitant for all (organic) alkaloids, which combine with it, pretty much as ammonia does, into precipitates insoluble in dilute mineral acids. A solution of the acid sufficient for this purpose may be obtained by saturating carbonate of soda solution with molybdic acid, adding phosphate of soda, one part for every five of Mo0 3, evaporating to dryness, fusing, dissolving in water, filtering, and adding nitric acid until the liquid becomes yellow. Metallic molybdenum is obtained by reduction of the trioxide in hydrogen gas at very high temperatures. It is thus obtained in small crystalline granules which are infusible even in the oxy- hydrogen flame. An alloy of the metal with four or five per cent. of carbon (formerly accepted as molybdenum) fuses in the oxy- hydrogen flame into a silver-white metal, of 8 6 specific gravity which is harder than topaz (Debray). Analysis. Molybdenum in all its forms is readily converted in to molybdic acid by oxidizing agents, such as nitric acid ; or if in non volatile forms into alkaline molybdate by fusion with carbonate of alkali and nitre. Alkaline molybdate is soluble in water ; the solution, on a gradual addition of hydrochloric acid, gives first a white precipitate, which then dissolves in the excess of acid. &quot;When a piece of zinc is added to such a solution, the latter, through gradual reduction of its Mo0 3 to lower oxides, assumes first a blue, oxidizing yellow in the heat, but almost colourless on cooling ; the reducing flame colours it dark brown, and may cause the separation of brown flakes of Mo0 2. Compare CHEMISTRY, vol. v. pp. 541, 542. MOMBASA, or less correctly MOMBAS, the Mwita of the Sawahili, a town on the east coast of Africa, in 4 4 S. lat., with the best harbour on all the Zanzibar mainland. The coralline island of which it occupies the eastern portion is 3 miles long by 2^ broad, and lies in the middle of a double inlet of the sea stretching northward into Port Tudor (so called after the English officer who surveyed it) and westward into Port Reitz (after the English resident who died while exploring the Pangani river in 1823). Except at the western end, the coast of the island consists of cliffs from 40 to 60 feet high. In the vicinity of the town palms, mangoes, guavas, baobabs, and cinnamon -trees flourish abundantly, and farther to the west are stretches of virgin forest, the haunt of monkeys, wild hogs, and hytenas. The citadel, originally constructed by Xeixas and Cabrera in 1635, still remains in good condition, &quot;a picturesque yellow pile with long buttressed curtains,&quot; but has preserved little of its Portuguese architecture. Of the twenty. Portuguese churches which Mombasa once contained, only two or three can be identified. A few of the houses are built of stone, but most of them are mere thatched huts. The population in 1844 was, according to Dr Krapf, from 8000 to 10,000, mostly Wasawahili, but with a considerable number of Arabs and some thirty or forty Banyans. In 1857 Burton estimated the inhabitants at 8000 to 9000, and in 1883 they numbered about 20,000. The Arabs, the Wamwita, and the Wakilindini (the two divisions of the Wasawahili residents, of which the former is the original stock) have each their own chief. In 1875-76 the Church Missionary Society, which made Mombasa one of its stations in 1844, established a settlement for liberated slaves at Freretown (Kisauni) on the mainland, opposite Mombasa. By 1881 it consisted of about 450 persons, of whom about one-fourth were children attending school. The pupils are taught to read both English and Sawahili (Ch. Miss. Intelligencer, 1875-76 and 1881). A branch station at Rabbai numbers 600 inhabitants. Mombasa takes its name from Mombasa in Oman. It is men tioned by Ibn Batuta in 1331 as a large place, and at the time of Yasco da Gama s visit it was the residence of Calicut Banyans and Christians of St Thomas, and the seat of considerable commerce. The &quot;king&quot; of the city, however, tried to entrap Da Gama, and with this began a series of troubles which give full force to the native name Mwita (war). The principal incidents are the capture and burning of the place by Almeyda (1505), Nuno da Cunha (1529), and Duarte de Menezes (1587) this last as a revenge for its submission to the sultan of Constantinople the building of the Portuguese fort (1594), the revolt of Yusuf ibn Ahmed (1631), the erection of the Portuguese citadel (1635), the five years siege by the imam of Oman (1660-65), and the final expulsion of the Portuguese (1698). In 1823 the Mazara family, who had ruled in Mombasa from the early part of the 18th century, placed the city under British protection ; but Britain soon withdrew, and left the place to be bombarded and captured by Sayyid Said of Zanzibar, who was obliged to make repeated attacks between 1829 and 1833, and only got possession in 1834 by treachery. A revolt against Zanzi bar in 1875 was put down by British assistance. See Capt. W. F. W. Owen, Narrative, &c. (1833) ; Capt. Thomas Bottler, Narrative, &c. (1835); Guillain, Voyage, (Paris, I860); Krapf, Travels, (1860); Burton, Zanzibar, (1872). XVI. 88