The sulphorets precipitate lead from its solutions, the sulphur falling clown in combination with the lead. Pure alka line solutions dissolve a small portion of lead, and corrode a considerable quanti ty : the solution is said to give a black co lour to the hair.
Oils dissolve the oxides of lead, and be come thick and consistent ; in which state they are used as the basis of plasters, cements for water-works, paints, &c.
In the dry way, lead alone is oxided and vitrified. When fused with fixed alkaline salts, it is converted into a dark coloured scoria, partly soluble in water. The neutral salts in general are not act ed upon by lead. Nitre oxides this me tal when heated with it, though scarcely any commotion or apparent flame is pro duced by its action. Sulphur readily dissolves it in the dry way, and pro duces a brittle compound, of a deep grey colour and brilliant appearance, which is much less fusible than lead itself; a property which is common to all the combinations of sulphur with the more fusible metals.
The phosphoric acid, exposed to heat together with charcoal and lead, be comes converted into phosphorus, which combines with the metal. This combina tion does not greatly differ in appearance from ordinary lead : it is malleable, and easily cut with a knife ; but it loses its brilliancy more speedily than pure lead ; and, when fused upon charcoal with the blow-pipe, the phosphorus burns, and leaves the lead behind.
Lead decomposes sal ammoniac, or mu riate of ammonia, by the assistance of heat : its oxides unite with the muriatic acid of that salt in the cold, and disen gage its volatile alkali. When the vola tile alkali is obtained by distilling sal am moniac with the oxides of lead, the resi due consists of the muriate of lead.
Litharge fused with common salt de composes it ; the lead unites with mu riatic acid, and forms a yellow compound, at present used in this country as a pig ment. The alkali either floats at top, or is volatilized by the heat, if strongly urg ed. The same decomposition takes place in the humid way, if common salt be ma cerated with litharge, and the solution will contain the pure alkali.
Lead unites with most of the metals.
Gold and silver are dissolved by it in a slight red heat. Both these metals are said to be rendered brittle by a small ad mixture of lead, though lead itself is ren dered more ductile by a small quantity of them. Platina forms a brittle compound with lead ; mercury amalgamates with it ; but the lead is separated from the mercu ry by agitation, in the form of an impalpa ble black powder, if oxygen be present, which is at the same time absorbed. Copper and lead do not unite but with a strong heat. If lead be heated so as to boil and smoke, it soon dissolves pieces of copper thrown into it : the mixture when cold is brittle. The union of these two metals is remarkably slight ; for, upon exposing the mass to a heat no greater than that in which lead melts, the lead almost entirely runs off by it self. This process, which is peculiar to lead with copper, is called eliquation. The coarser sorts of lead, which owe their brittleness and granulated texture to an admixture of copper, throw it up to the surface on being melted to a small heat. Iroil does not unite with lead, as long as both substances retain their me tallic form. Tin unites very easily with this metal, and forms a compound which is much more fusible than lead by itself, and is for that reason used as a solder for lead. Two parts of lead and one of tin, form an alloy more fusible than either metal alone ; this is the solder of the plumbers. Bismuth combines readily with lead, and affords a metal of a fine close grain, but very brittle. A mixture of eight parts bismuth, five lead, and three tin, will melt in a heat which is not Sufficient to cause water to boil. Antimo ny forms a brittle alloy with lead. Nickel, cobalt, manganese, and zinc, do not unite with lead by fusion.
It will appear, from the foregoing ob servations, that the uses of lead are very extensive. It is easily reduced to thin .sheets, adapted to the covering of build ings; to be formed into pipes of all sizes, and fitted for divers purposes. Its oxides are used as paints ; in the manu facture of glass; and in the glazing of earthen-ware, he.
LExn, black. See the article Iaox.