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PUOPERTIES OF LEAD.

PROPERTIES OF LEAD.

Lead is of a bluish-white colour when fresh cut. It is mal-leable. It soon tarnishes in the atmosphere. It may easily be<;ut with a knife, and stains the fingers bluish-grey when rubbed.It fuses at 540° Fahr. and renders other more refractory metalsfusible. It becomes vitrified in a strong and continued heat, andvitrifies various other metals. It is the least elastic of all themetals. It is very laminable, but it possesss very little ductility.Its specific gravity is 11.435. It crystallizes by cooling in smalloctahedra. When fused its surface first becomes yellow andthen red. It unites by fusion with phosphorus and sulphur.The greater part of the acids act upon it. The sulphuric acidrequires the assistance of a boiling heat. Nitric acid is decom-posed by it. Muriatic acid acts very weakly on if Acetic aciddissolves it. Fluoric acid attacks it by heat, and slightly in thecold. It combines with other metals, but few of its alloys areapplied to any use. When combined with mercury it forms acrystallizable alloy which becomes fluid when triturated withthat of bismuth.

METHOD OF OBTAINING LEAD.

In order to obtain lead in the great way the ore is picked fromamong the extraneous matter with which it was naturally mixed.It is then pulverized and washed. It is next roasted in a rever-beratory' furnace in which it is to be agitated, in order to bringall its surfaces in contact w ith the air. When the external partsbegin to soften, or assume the form of a paste, it is covered withcharcoal, the mixture is stirred, and the heat increased gradually)the lead then runs on all sides, and is collected at the bottom ofthe furnace, which is perforated so as to permit the metal toflow into a receptacle defended by a lining of charcoal.

The scoria remaining above in the furnace still retain a con-siderable proportion of lead; in order to extract it die scoria