CHLORIDE OF LEAD.
511
Lyons found litharge to be irritant in large doses of half an ounce,”(Christison, op. cit. p. 509).
From its external use ill consequences have sometimes resulted.
Uses. —The oxides of lead are never employed internally. Lithargeis sometimes sprinkled over ulcers, as an astringent and desiccatingsubstance.
In pharmacy, litharge is used in the preparation of emplastrumPLUMBI, CEltATLM SAFONIS, ACETAS FLUMBI, and LIQUOR PLUMB IDIACETATIS.
The plumbi oxydiim hydratum, Pli. Lond., is directed to be used inpreparing Quince Sulphas. But the Pharmacopoeial process for makingthe latter substance has not been found by manufacturers to answer,and, therefore, the hydrated oxide of lead is, in fact, not employed inpharmacy.
Hair Dyf.. —Various powders, pastes, and liquids, have been pre-pared for dyeing the hair brown or black ( Journ. de Chern. Med. ii. 250,2” de Ser.) In general a mixture, or rather compound, of litharge andlime is employed. The preparation sold as Orfila’s hair dye is of thiskind. The proportions are one part of each, or three parts of lithargeand two of lime. Sometimes carbonate of lead is partially or whollysubstituted for litharge. The mixture is made into a paste with hotwater or milk, and applied to the hair for four or five hours, thepart being enveloped in oil-skin or a cabbage leaf. The water causesthe oxide of lead to combine with the lime, and thereby form a salinecompound, called plumbite of lime. The lime is useful by removing thefatty matter of the hair, while the oxide of lead forms, with the sulphurcontained in the oil of the hair, a black sulphuret of lead. Dyed hair isdry and crisp. The mode of detecting stained hair has been describedby the late Dr. Cummin {Lond. Med. Gaz. xix. 215), and by Devergie{Med. Leg. ii. 931).
Natural History. —Chloride of lead occurs in the mineral- kingdom.
Preparation. —In the London Pharmacopoeia this compound is di-rected to be prepared as follows :—Dissolve 19 ounces of acetate of leadin three pints of boiling distilled water, and 6 ounces of chloride ofsodium in one pint of boiling distilled water: mix. Wash the precipi-tate when cold with distilled water, and dry it.
In this process one equivalent or 163 parts of dry acetate of lead aredecomposed by one equivalent or 60 parts of chloride of sodium; bywhich one equivalent or 140 parts of chloride of lead are precipitated,and one equivalent or 83 parts of acetate of soda remain in solution.
REAGENTS.
1 eq. Acetate of ( 1 e( L Acetic Acid ...Lead.... 163 (leq. Ox. Lead 112
1 eq.Chloride of U eq. Sodium .
Sodium.. 60 (1 eq. Chlorine.
.51
leq.Oxyg.leq. Lead 10-p.24
1 eq. soda 32
RESULTS.
1 eq. Acetate Soda 831 eq. Chlorde Lead 140
Hydrochloric acid occasions the precipitation of more chloride of leadafter the action of the chloride of sodium is over; so that there must besome compound of lead in solution (Phillips, Transl. of Pharm. 3rd ed.)