LEACOCK, RAMBLE JAMES, 1795-1856; b. Cluff's Bay, Barbadoes: descended frown a noble English ancestry. His father was a slaveholder in Barbadoes. The son received his early education at Codrington college, Barbadoes. became reader in his native parish, studied with his pastor, rev. W. hi. Harty, and obtained deacon's orders in 1826.
assistant priest of St. John's church he gave the privileges of the church to all the slaves of the parish, at the same time freeing his own slaves. This awakened so much opposition that the bishop removed hint to St. Vincent, and then to Nevis. Difficulty with the bishop, insurrection of the slaves, and fall of property occurring, be removed to the United States, where he was settled in Kentucky Tennessee. in 1840 he took charge of a small farm near New Brunswick, N. J., supplying churches in the vicinity. In 1841 and 1847 he revisited the West Indies, preaching vehemently against the prevailing vices. In 1855 he sailed for Africa as a missionary of the West Indian ,church association, and landed at Freetown, Sierra Leone. By the aid of the bishop and governor he founded the station, the Rio I'ongas. From a converted negro chief •he obtained a site for his dwelling and chapel; opened a school for boys, which was very successful. His health failing he went to Sierra Leone, but soon returned to his post, .Where he died. A. large missionary field was opened as the result of his labors.
LEAD (symb. Pb., equiv. 103.7—new system, 207—spee. gray. 11.4) is a bluish-white metal of considerable brilliancy, which soon disappears on exposure to the air, owing to the formation of a thin film of oxide. It is so soft that it may be readily cut with a knife, or may be made to take impressions, and it leaves a streak upon paper. It may be cut or beaten into thin sheets, but in ductility and tenacity it is low in the scale of _metals. It is readily fusible at a temperature of about 625°, and at a higher tempera ture it absorbs oxygen rapidly from the air, and the oxide thus formed volatilizes in the form of white fumes.
The combined action of air and water on lead is a subject of great practical impor tance, in consequence of the metal being so frequently employed in the construction of cisterus• and water-pipes. The lead becomes oxidized at the surface, and the water dissolves the oxide; this solution absorbs the carbonic acid of the atmosphere, a film of hydrated oxycarbonate of lead (PbO,HO is deposited in silky scales, and a fresh portion of oxide of lead is formed and dissolved, and in this way a rapid corrosion of the metal ensues. This action is materially increased by the presence of some salts
and diminished by the presence of other salts in the water. It is much increased by the occurrence of chlorides (which, as chloride of sodium, is often present in spring water), and of nitrates and nitrites (which are often present in and river waters, from the decomposition of organic matter); while it is diminished by the sulphates, phos phates, and carbonates, and especially by carbonate of lime, which is an extremely common impurity in spring water. In the latter case, a film of isoluble carbonate of lead is rapidly formed on the surface, and the metal beneath is thus protected from the action of the water. If, however, the water contain much carbonic acid, the carbonate of lead may be dissolved, and considering the dangers that arise froni the use of water impregnated with lead, cisterns constructed of slate are far preferable to leaden ones.
Pure lead is of very rare occurrence. Almost all the lead of commerce is obtained from galena, the native sulphide of lead, by a process to be presently explained. The lead thus obtained is often nearly pure, and to obtain it perfectly pure it should be reduced with black flux from.the oxide left by igniting the pure nitrate or carbonate.
The compounds of lead with oxygen arc four in number—viz., a suboxide, Which is a black powder of no importance; a protoxide, PbO, which is the base of the ordinary salts of the metal; a binoxide, and red lead, which is a compound of the two last-named oxides, and is usually represented by the formula The protoxide is commonly known as litha•ge. It is obtained on a large scale by the oxida tion of lead in a current of air, when it forms a scaly mass of a yellow or reddish tint. If the oxidation be effected at a temperature b !ow that rcquir for the fusion of oxide, a yellow powder, termed massicot, is obtained. Litharge is much used by the assayer (see ASSAY) as a flux; it enters largely into the composition of the glaze of common earthenware, and it is employed in pharmacy in the preparation of plasters. A mix ture of 1 part of massicot with 10 of brickdnst, made into a paste with linseed-oil, forms the compound known as dhil mastic, which, from the hardness with which it sets, is frequently employed to repair defects in stone-facings.