PREPARATIONS OF LEAD.

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made by mixing Goulard's extract (20 parts) and camphor cerate (80 parts); it is an admirable dressing to excoriated and blistered surfaces, burns, scalds, etc. Linimentum plumbi subacetatis (liniment of lead subacetate) is made by mixing cottonseed oil with Goulard's extract.

PLUMBI IODIDUM (Lead Iodide) (PbI) is made by the double reaction of solutions of lead nitrate and potassium iodide. It is a bright-yellow, heavy, inodorous powder, volatilizable by heat, sparingly soluble in cold water, but more soluble in boiling water. It is used chiefly to reduce the volume of indolent tumours, and may be given internally in the dose of gr. iij-iv, or more, in pill; but it is principally employed externally in the form of ointment (10 parts to benzoinated lard 90 parts).

PLUMBI NITRAS (Lead Nitrate) (Pb2NO3), made by dissolving litharge in diluted nitric acid, occurs in white, nearly opaque, octahedral crystals, permanent in the air, of a sweet, astringent taste, and soluble in water and alcohol. It may be given internally, as a sedative astringent, in doses of gr. to gr. j, twice or thrice daily, in pill or solution. But its principal use is as a topical agent in the treatment of wounds, ulcers, and cutaneous affections. Dr. Fordyce Barker recommends it as an application to fissured nipples (gr. x in glycerin 3j). The breast must be carefully washed before nursing. Ledoyen's Disinfecting Fluid is a solution of lead nitrate 3j in water f3j.

PLUMBI OXIDUM (Lead Oxide) (PbO), or Litharge, is prepared by blowing air through melted lead, and is obtained also in the process for extracting silver from argentiferous galenas. It occurs in minute yellowish or orange-coloured scales, insoluble in water, and is never employed internally. It is sometimes sprinkled over ulcers, but its chief use is in the preparation of emplastrum plumbi, or lead plaster (called also diachylon), which is made by boiling litharge with olive oil in water, and is, chemically, a mixture of lead oleate and margarate. It serves as a basis for most of the other plasters. Unguentum diachylon (diachylon ointment) consists of lead plaster 60 parts melted with olive oil 39 parts, and incorporated when partly cool with oil of lavender I part. Emplastrum saponis (soap plaster),

made by rubbing up soap with lead plaster, is an excellent discutient.

PLUMBI CARBONAS (Lead Carbonate), or White Lead, is manufactured in this country by exposing lead to the fumes of vinegar or acetic acid, carbonic acid being derived from the fermentation of tan, in which the pots containing lead are packed; lead oxyacetate as formed, is converted into carbonate. It is a white powder, without smell or taste, and insoluble in water, and, as it occurs in commerce, is a compound of lead carbonate and hydrate (2PbCO.Pb2HO). It is never administered internally, but it is employed as a dusting powder-though there is danger of its absorption. Uuguentum plumbi carbonatis (10 parts to benzoinated lard 90 parts) is a good application to burns, etc. White paint is used for the same purpose, but when applied to a large surface it may produce lead-poisoning.

ALUMEN-ALUM.

Alum is a double salt, an aluminium and potassium sulphate (K2A124SO.24H2O). It is manufactured from aluminous schist, and sometimes by the direct combination of its constituents. It crystallizes in regular octahedrons; but it is commonly found in the shops in large colourless, transparent crystalline masses, without any regular form. It has an astringent and sweetish acid taste; by exposure to the air it slowly effloresces; it is soluble in cold water, and more so in boiling water; and when heated it undergoes the watery fusion, swells up, and gives out its water of crystallization, and is converted into a white, spongy mass, called dried alum. The alkalies and their carbonates, lime solution, magnesia and its carbonate, potassium tartrate, lead acetate, and tannic acid are incompatible with alum. It is aided in its action by the vegetable and mineral astringents.

Besides the potassium alum, there are varieties in which the potassium is replaced by some other base, as ammonium or sodium; the officinal alum was formerly the aluminium and ammonium sulphate, but this has been superseded by potassium alum.

Physiological Effects.-The immediate topical effect of alum is that of a powerful astringent, in virtue of a chemical action

on the tissues. When it is applied to a part in large quantities, the astriction is soon followed by irritation; and thus, taken internally in excessive doses, it gives rise to vomiting, griping, purging, and even inflammation of the gastro-enteric mucous membrane. After its absorption it acts as an astringent on the system generally, and produces astriction of the tissues and fibres, contraction of the capillaries, and a diminution of secretion, thus producing constipation. It is eliminated chiefly with the fæces. After large doses, Orfila detected it in the urine of dogs. Death has resulted in man from dried alum 3jss.

Medicinal Uses-Alum is employed internally in hæmorrhages, chronic diarrhoea, colliquative sweating, diabetes, etc., and it is sometimes combined with cubeb in the treatment of gleet and gonorrhoea, as in the following prescription: R. Pulveris aluminis, 3j; Pulveris cubebæ, živ; Pulveris cinnamomi, 3ss; M. et sig. Tablespoonful in half a glass of water 3 times a day; an efficient mixture when it does not disorder the stomach. Alum is also used as an injection in leucorrhoea. It has also been given as an emetic in croup. Its use in lead-colic has been alluded to. As a topical remedy it is valuable as an astringent antiphlogistic in ophthalmia, diphtheria, tonsillitis, etc.; to produce contraction of the tissues, in relaxation of the uvula, prolapsus ani, etc.; as a styptic in hæmorrhages; and to arrest excessive secretion from the mucous surfaces. In hæmoptysis and bronchitis, a strong solution of alum may be applied by atomization. Dose, gr. x-xxx, in powder or solution, or made into pills with some tonic extract, and combined with an aromatic, as nutmeg, to prevent nausea. It may be agreeably given in the form of whey, prepared by boiling 3ij with milk Oj, and straining, of which the dose is f3ij. Topically, it is. employed in the forms of powder, solution, and poultice, the latter of which is made by rubbing up whites of eggs with alum, and is applied to the eye in ophthalmia, between folds of linen. Dried alum (alumen exsiccatum) is employed internally in the dose of gr. v-x, and externally as a mild escharotic.

ALUMINII SULPHAS (Aluminium Sulphate) (Al„3SO....18H2O) is employed externally as an astringent and antiseptic application to ulcers, an injection in gonorrhoea, etc. The aqueous

solution is used to preserve bodies for dissection. A paste, made of a mixture of aluminium sulphate and sp. nitrous ether, applied to the cavity of a carious tooth, is a good remedy for toothache.

ORDER VI.—STIMULANTS.

Stimulants are medicines which produce a rapid and temporary exaltation of the vital functions. Their influence is most conspicuous in conditions of morbid depression, when a marked tolerance of their action is established, and large amounts are borne. In health, when the powers of the system are at the normal standard, stimulants soon induce depression. Topically, they irritate and inflame the parts to which they are applied, and hence are classed with irritants.

Stimulants are employed principally in disorders known as asthenic, and in all conditions of the system attended with exhaustion. From their action in arousing the energies of the nervous system, they exercise a control over many nervous disorders, particularly those of a spasmodic nature. They are also frequently given with a view to their action on some one or other of the secretions. As stimulants to the gastro-intestinal canal, they are administered to promote digestion (when they are called stomachics) and to dispel flatulence (when they are known as carminatives). Topically, they are employed as rubefacients, vesicants, etc.

The more powerful and rapid stimulants are called diffusible. In overdoses, they act as violent narcotics and sedatives. The diffusible stimuli usually employed are vinous and spirituous liquors and the preparations of ammonia. Vegetable stimulants which contain a volatile oil are termed aromatics, and are usually given as stomachics and carminatives. The volatile oils are also employed as local irritants.

DIFFUSIBLE STIMULANTS.

ALCOHOL.

Alcohol is a product which results from a process termed the vinous fermentation, in substances containing grape-sugar. At a temperature of 80° F., the presence of a fermenting

body converts a solution of grape-sugar into alcohol and carbonic acid. Starchy substances, being convertible into grape-sugar, also yield alcohol. Alcohol is obtained from vinous or fermented liquors by repeated distillation. It is, chemically, an ethyl hydrate (C,H,HO). Officinal alcohol

should be of the sp. gr. 0.820. It is a colourless, inflammable liquid, wholly vaporizable by heat, and unites in all proportions with water and ether. Contamination of fusel oil or amylic alcohol may be detected by agitation with concentrated sulphuric acid, when, if the alcohol becomes coloured, the presence of the impurity is indicated in proportion to the depth of the colour; or solution of silver nitrate, with exposure to a bright light, will convert fusel oil into a black powder.

Physiological Effects.—Alcohol is the intoxicating ingredient of all vinous and spirituous liquors. Locally, alcohol acts as an astringent by hardening the albumen and condensing the tissues. It evaporates rapidly, causing a feeling of coolness. When evaporation is prevented, it acts as an irritant (due to absorption and paralysis of the cutaneous vessels), and may even produce inflammation. When inhaled it may produce anææsthesia, stupor and death. Nervous system: when taken internally, in small doses, it stimulates the cerebral hemispheres, possibly by the hyperæmia induced; in large doses it causes excitement with impaired co-ordination of ideas; and in excessive doses it produces coma. Small doses stimulate the spinal cord, while larger amounts weaken the centres governing automatic motion and co-ordination, and lessen the sensibility of the cutaneous nerves, especially that of the fifth pair of cranial nerves. Large doses paralyze the vaso-motor nerves, giving rise to dilatation of the arterioles, flushing of the surface, and sensations of heat. In inflammatory diseases, medicinal doses contract the arterioles by giving tone to the vaso-motor system, and prevent the migration of white corpuscles (Farquharson). In toxic doses, the nervous centres are involved in the following order: 1. The gray matter of the convolutions and the higher functions of animal life (shown by disordered intellection). 2. The basic ganglia (shown by disordered sensation and motion). 3. The cerebellum (shown by disordered equili