latter case with the formation of a blue solution which on heating becomes colourless, molybdenum trioxide being formed with the liberation of sulphur dioxide.
Molybdenum combines with oxygen to form many oxides, the most important of which are: the monoxide, MoO.n(H2O), the sesquioxide, Mo2O3, the dioxide, MoO2, and the trioxide, MoO3. Molybdenum monoxide, MoO.n(H2O), is a black powder obtained when the dichloride is boiled with concentrated potash solution. According to W. Muthmann and W. Nagel (Ber., 1898, 31, p. 2009), this oxide does not exist, the reaction leading to the formation of an hydroxide according to the equation: Mo3Cl4(OH)2+4KHO+3H2O＝3Mo(OH)3+4KBr+3H. Molybdenum sesquioxide, Mo2O3, a black mass insoluble in acids, is formed by heating the corresponding hydroxide in vacuo, or by digesting the trioxide with zinc and hydrochloric acid. Molybdenum dioxide, MoO2, is formed by heating sodium trimolybdate, Na2Mo3O10, to redness in a current of hydrogen (L. Svanberg and H. Struve, Jour. prak. Chem., 1848, 44, p. 301), or by long fusion of a mixture of ammonium molybdate, potassium carbonate, and boron trioxide (W. Muthmann, Ann., 1887, 238, p. 114). It forms quadratic prisms, having a violet reflex and insoluble in boiling hydrochloric acid. Molybdenum trioxide, MoO3, is prepared by oxidizing the metal or the sulphide by heating them in air, or with nitric acid. It, is a white powder, which turns pale yellow on heating, and melts at a red heat. It sublimes in small rhombic tables or needles, and is slightly soluble in cold water, the solution possessing an acid reaction. Several hydrated forms of the oxide are known, and a colloidal variety may be obtained by the dialysis of a strong hydrochloric acid solution of sodium molybdate. Molybdenum trioxide, like chromium trioxide, is an acidic oxide, and forms salts known as molybdates. The normal molybdates show a tendency to pass into polymolybdates. The molybdates are also capable of combining with other oxides (such as phosphorus and arsenic pentoxides) yielding very complex salts. The ordinary ammonium molybdate, used as a test reagent for phosphates, is a salt of composition (NH4)10Mo12O41; it has been examined physicochemically by J. Sand and F. Eisenlohr (Abst. J.C.S., 1907, ii. pp. 178, 179). The molybdates may be recognized by the fact that they give a white precipitate on the addition of hydrochloric or nitric acids to their solutions, and that with reducing agents (zinc and sulphuric acid) they give generally a blue coloration which turns to a green and finally to a brown colour.
Molybdenum combines with the halogen elements in varying proportions, forming with chlorine a di-, tri-, tetra- and penta-chloride, and similar compounds with bromine and iodine. Molybdenum dichloride (MoCl2)3 or Cl4Mo3Cl2 (chlormolybdenum chloride), is prepared together with some tetrachloride) by heating the trichloride in a stream of carbon dioxide (C. W. Blomstrand, Jour. f. prak. Chem., 1857, 71, p. 449; 1861, 82, p. 433). It is a yellow amorphous powder which is soluble in dilute alkalis, the solution on acidification giving an hydroxide, Cl4Mo3(OH)2, which is soluble in nitric acid, and does not give a reaction with silver nitrate. The molecular weight determinations of W. Muthmann and W. Nagel (Ber., 1898, 31, p. 2009) show the salt to possess the composition Mo3Cl6. Molybdenum trichloride, MoCl3, is obtained when the pentachloride is heated to a temperature of about 250° C. in a current of hydrogen. It forms red crusts, is insoluble in cold water, but is decomposed by boiling water. It is easily soluble in hot nitric acid. Molybdenum pentachloride, MoCl5, is obtained when molybdenum is gently heated in dry chlorine (L. P. Liechti and B. Kempe, Ann., 1873, 169, p. 345). It is a dark-coloured crystalline solid which melts at 194° C. and boils at 268° C. It fumes in moist air and deliquesces gradually. It is occasionally used as a chlorine carrier. It is soluble in absolute alcohol and in ether. Molybdenum disulphide, MoS2, is found as the mineral molybdenite, and may be prepared by heating the trioxide with sulphur or sulphuretted hydrogen. It is a black crystalline powder, resembling graphite in appearance. It is readily oxidized by nitric acid, and when strongly heated in a current of hydrogen is reduced to the metallic condition. Molybdenum trisulphide, MoS3, is obtained by saturating a solution of an alkaline molybdate with sulphuretted hydrogen and adding a mineral acid. It is a brown powder which on heating in air loses sulphur and leaves a residue of the disulphide. A tetrasulphide, MoS4, has also been described.
Many varying values have been given for the atomic weight of molybdenum. J. J. Berzelius (Pogg. Ann., 1826, 8, p. 23), by converting lead molybdate into lead nitrate, obtained the value 95·2; while J. B. A. Dumas (Ann., 1860, 113, p. 32), by converting the trioxide into the metal, obtained the value 95·65. K. Seubert and W. Pollard (Zeit. anorg. Chem., 1895, 8, p. 434) using this second method obtained the value 96·28; whilst E. F. Smith and P. Maas (Zeit. anorg. Chem., 1894, 5, p. 280), by heating pure sodium molybdate in hydrochloric acid and estimating the amount of sodium chloride formed, obtained the value 96·087.
MOLYNEUX. This historic English name came into the country from France at the time of the Norman Conquest through William de Molines (Moleyns, Molyneux), who obtained a grant of Sefton, in Lancashire, whence come the earls of Sefton to-day. His descendant Adam de Molyneux (Moleyns or Molins), who died in 1450, was bishop of Chichester and keeper of the privy seal; he was a son of Sir Richard Molyneux of Sefton, and uncle of the Sir Richard Molyneux (d. 1459), the Lancastrian and favourite of Henry VI., whose descendant Richard Molyneux (1593–1636) was created in 1628 1st Viscount Molyneux of Maryborough, a title now merged in that of Sefton (created 1771). Another Molyneux family of some importance is the Irish one, descended from Sir Thomas Molyneux (1531–1597), Irish chancellor of the exchequer, who, born at Calais, settled in Ireland in 1576. He was the great-grandfather of Sir Thomas Molyneux, Bart. (1661–1733), a well-known physician and zoologist, and of William Molyneux (1656–1698), the philosopher, astronomer and politician, the friend of Locke, and author of Dioptrica nova (1692), whose famous work on the legislative independence of Ireland (The Case of Ireland, &c. 1698) created much stir at the time. The latter’s son Samuel Molyneux (1689–1728), was also a well-known astronomer.
MOMBASA, the principal seaport of British East Africa,
in 4° 4′ S., 39° 43′ E., 150 m. N. of Zanzibar. Pop. about
30,000. Mombasa is built on a coralline island which nearly
fills the mouth of a deep arm of the sea. The channel on either
side of the island-Mombasa to the N.E., Kilindini to the S.W.—affords
safe harbourage, and each leads to a deeper ramification
of the sea, Mombasa Harbour to Port Tudor, Kilindini Harbour
to Port Reitz. Mombasa town is on the N.E. side of the island,
2 m. from Kilindini, with which it is connected by rail and
tramways. Viewed from the sea Mombasa has a picturesque
appearance, the most conspicuous object being the fort, built
on a coral hill 40 ft. high. Except for the main street and
Government Square (close to the harbour and containing the
customs-house and other official buildings), Mombasa proper
presents the usual aspect of an Oriental city-a maze of narrow,
irregular streets and lanes. To the south, overlooking the sea,
is the European suburb. There are Anglican and Roman
Catholic churches (the Roman Catholic church and mission
house is one of the finest buildings in Mombasa), mission schools,
Hindu, Parsee, and Mahommedan temples, and hospitals and
law courts, the last named completed in 1902. Built into the
façade of the courts is a stone with an inscription recording
the building of a fort, dedicated to St Joseph, by the Portuguese
at Kilindini in 1666. This stone was found in the ruins of Fort
St Joseph. Mombasa Fort, or citadel, quadrangular in form,
was built by the Portuguese in 1593–1595 (as an inscription in
the interior testifies), was dedicated to the Saviour, and known
as the Jesus Fort. It bears the symbol I.H.S. The fort was
repaired by Seixas de Cabreira in 1635, the restoration being
recorded in an inscription over the gateway. By the British
authorities the fort is used as a military store and central gaol.
In the public garden on the point of the town facing the sea
a bronze statue of Sir William Mackinnon—to whom Mombasa
owes its renaissance—has been placed. The population of
the city is cosmopolitan, with three well-marked racial distinctions:
the Arab (Swahili), the Indian and the European. The
climate is fairly healthy, and Europeans live there with comfort.
The harbour at Mombasa is more than a mile in length, but only 1200 ft. in width. It is consequently not so suitable for large ships as Kilindini (“the place of deep water”), which possesses the finest land-locked harbour on the East Coast of Africa. The entrance is about the same width as that of Mombasa, but Kilindini Harbour widens to 12 m. and is 3 m. long, the depth of water varying from 25 to 30 fathoms. Kilindini is a depot of the British navy. Port Reitz, which opens out of Kilindini Harbour westward, is 4 m. long and 1 m. broad, with excellent anchorage. At Kilindini is a pier alongside which ships 450 ft. in length and drawing 27 ft. can load and unload cargo. Here is the virtual terminus of the Uganda railway, and the offices, workshops and hospital connected therewith, also a branch customs-house. The Uganda railway crosses to the mainland on a bridge, 12 m. long, built over the shallow channel Which on the north-west separates the island from the continent. Mombasa is the outlet for the produce of a large tract of territory, including the European
