used to disinfect water-closets and sinks. The evaporation of this solution yields ZINCI CHLORIDUM (Zinc Chloride) (ZnCl2), a whitish-gray, semitransparent, deliquescent mass, having the softness of wax, and soluble in water, alcohol, and ether. Its local action is that of a powerful caustic, and it is one of the best escharotics that can be exhibited, to produce healthy granulations in malignant or indolent ulcers, especially in lupus. It may be used as a lotion in the strength of gr. ij to f5j of water, or dissolved in a little. alcohol, or in the form of paste, made with one part of the salt to two or four of flour. A solution of zinc chloride is employed as an antiseptic, and is also injected into the blood vessels of anatomical subjects to preserve them for dissection. Burnett's Disinfecting Fluid is a solution of about gr. cc in water fɔ̃j. ZINCI IODIDUM (Zinc Iodide) (ZnI2) is made by digesting an excess of zinc with iodine diffused in water. It occurs in the form of a white deliquescent mass, or of fine needles, of a metallic, styptic taste, very soluble in water. Externally, it is a most valuable local stimulant and escharotic, equal if not superior in effect to the chloride, and is much used. ZINCI VALERIANAS (Zinc Valerianate) (Zn2C¿H,O2.H2O) is prepared by the double reaction of sodium valerianate and zinc sulphate. It occurs in white, pearly scales, having a faint odor of valerianic acid, and a metallic, styptic taste. It dissolves in 100 parts of water and 40 of alcohol. Used in epilepsy and nervous affections, in the dose of gr. i-ij, repeated several times a day. ARGENTI PRÆPARATA-PREPARATIONS OF SILVER. In the metallic state, silver is wholly inert. The only preparation which is extensively employed is ARGENTI NITRAS (Silver Nitrate). This salt (AgNO3) is obtained by dissolving silver in diluted nitric acid. It is anhydrous, and occurs in transparent, colorless, shining, heavy, rhombic plates, which have a strongly metallic and bitter taste, are wholly soluble in distilled water, and become blackened by the action of light in the presence of organic matters. Its solution yields with hydrochloric acid or sodium chloride a white precipitate, entirely soluble in ammonia. Physiological Effects.-The topical action of silver nitrate to mucous membranes is that of a caustic, by reason of its coagulating action on albumen. This action does not extend deeply, since a superficial protecting pellicle is formed. When moistened and applied to the skin, a white stain is formed, which soon becomes black on exposure to light, by reduction of the silver to the metallic state. Internally-Nervous system: in animals, hypodermic injections of silver hyposulphite and albuminate have caused paraplegia. In small doses, tetanic excitement, and in toxic, convulsions, were produced. On man the silver salts have caused vertigo, loss of memory and nervous depression. The effects of silver on the nervous system are centric and not peripheral. Circulation: the intravenous injection of the silver salts impairs the coagulability of the blood, which is found to be dark and pitchy in color. Other symptoms noted by this method were probably due to the production of embolism and thrombosis. The silver salts do not exert a toxic influ`ence on the heart. They have a metallic, styptic taste. Small doses (oxide, gr. 4, nitrate, gr. %) may be taken with considerable impunity by the stomach. But, in excessive quantity (of nitrate gr. iij-v), it may occasion gastro-enteric irritation, with disturbance of the nervous system; and in these cases the antidote is common salt (sodium chloride), or any inert chloride, which produces, when in contact with the nitrate, sodium nitrate and silver chloride. Silver nitrate has been thought always to undergo conversion into a chloride in the stomach; but more probably it unites with albuminous matters, which render it soluble. In medicinal doses, it has a corroborant action on the nervous system; and, after prolonged use, since its elimination takes place slowly, produces a peculiar indelible blueness or slate color of the true skin (argyria), due to a deposition of the metal in the tissues. This, it has been asserted, is preceded by a peculiar blue line on the gums, resembling that produced by lead poisoning. Prolonged use of the silver salts (in animals) causes a marked loss of weight. Elimination takes place by means of the bile, kidneys (chiefly) and intestines.* Medicinal Uses.-Internally, silver nitrate has been employed *Journal de l' Anatomie et de Physiologie, 1873, p. 289. in the treatment of epilepsy, but it is much inferior to the bromides in the treatment of this intractable affection; and its effect. in discoloring the skin is an objection to its protracted use. It is used also successfully in locomotor ataxia, being especially extolled by Rosenthall, Charcot, and others, in the dose of gr. 4, t. d.; but in this disease the galvanic current, in addition to medicines, renders important aid. In gastric ulcer and chronic gastritis it is also efficacious in small doses in pill form, after the stomach is afforded rest by liquid diet, preferably with milk. As an astringent in chronic dysentery and diarrhoea, combined with opium its exhibition may prove serviceable. But it is as an external agent that it is most resorted to. It is one of the best applications that can be made to inflamed mucous membranes, and, either in the solid form or in solution, it is employed in every variety of inflammation of this tissue. It is also extensively used to produce healthy granulations in wounds and ulcers, to arrest the progress of erysipelatous inflammation and variolous pustules, in porrigo and other skin diseases. The strong injections of silver nitrate formerly used to abort acute gonorrhoea are now rarely resorted to. In this disease, either of the male or female urethra, the best results are obtained by using solutions of the strength of gr. 4-j to water f3j, care being taken to avoid staining the clothing with it. As a collyrium it is contra-indicated when ulcer of the cornea exists, for fear of forming an opacity. If a strong collyrium be used (gr. v-x-f3j), in uncomplicated conjunctivitis for the relief of which it is an excellent application, the effect on the conjunctiva should be counteracted by flushing it out with weak solution of salt and water, or even with cold water alone. Silver nitrate stains can be removed by moistening the spot with tincture of iodine and then washing it with solution of sodium hypophosphite. It may be used to destroy the virus of poisoned wounds, but its action as a caustic is too superficial to be of much service for this purpose. Administration.-The dose of silver nitrate internally is gr., gradually increased to gr. or j, t. d., in pill, and given soon after a little light food has been taken. For external use, solutions are made of various strengths, from gr. ij-5ss or more in f3j of distilled water. An ointment is also employed. ARGENTI NITRAS FUSUS (Moulded Silver Nitrate-Lunar Caustic). For external use, in the solid form, silver nitrate is melted and poured into small moulds. ARGENTI NITRAS DILUTUS (Diluted Silver Nitrate) consists of 50 per cent. each of silver nitrate and potassium nitrate. It is used externally. ARGENTI OXIDUM (Silver Oxide) (Ag2O) is obtained by adding solution of potassa to a solution of silver nitrate. It is a tasteless, olive-brown powder, very slightly soluble in water. Its action and applications are analogous to those of the nitrate, and it is considered to be free from liability to discolor the skin. Dose, gr. ss-j, twice or thrice daily in pill. ARGENTI IODIDUM (Silver Iodide) (AgI) may be used in gastric and uterine affections instead of the nitrate. It is also said to have some alterant effects. Dose, gr. j-ij. BISMUTHI PRÆPARATA-PREPARATIONS OF BISMUTH. Metallic bismuth is inert. The salts are very insoluble, but to a slight extent are absorbed and eliminated* slowly, as bismuth has been found in the urine, blood, etc., after their administration. The unabsorbed residue, passing down the alimentary canal, is converted into a sulphide and colors the stools black. BISMUTHI SUBNITRAS (Bismuth Subnitrate). This salt is prepared by forming bismuth nitrate by dissolving bismuth in diluted nitric acid, suitable means at the same time being taken to get rid of arsenical contamination, as metallic bismuth generally contains arsenic. Bismuth subnitrate, known as pearl white and magistery of bismuth (BIONO3.H2O), is a white, inodorous, tasteless powder, insoluble in water. Its medical properties are tonic, sedative and astringent. It is used chiefly to allay nausea and check vomiting in chronic affections of the stomach, as ulcer, in which gr. xv-xx should be given t. d., to relieve the pain of gastralgia, and also as an astringent in subacute and chronic diarrhœa. As bismuth exerts its astringent influence on the intestinal tract by a local protective action, in the diarrhoea of adults it * Journal de l'Anatomie et de la Physiologie, 1873, p. 243. may be given, advantageously, in large doses (5ss-j), to be taken one hour before each meal. It is particularly useful in any form of diarrhoea where the stools contain mucus; and acute cases of diarrhoea occurring during the summer season are frequently benefited by it also. The following combination is of great service: R Morphinæ sulphatis, gr. 1⁄2-j; bismuthi subnitratis, 3j-ij; sodii bicarbonatis, 3j; sacchari lactis (seu pulveris cinnamomi), 3ij. M. et div. in chart. xii. Sig.-One powder after each alvine dejection. It is often advantageously given suspended in an emulsion of castor oil with laudanum, in these and similar complaints. Dose, gr. v-xx, or even 5ss, in powder or pill. Externally, it is a good remedy in skin diseases, in the form of ointment. The following forms a good antiseptic application in the treatment of ulcers:-R Iodoformi, 5j; acidi borici, ɔ̃ij; bismuthi subnitratis, 3iv; petrolati, 3ij. M. Sig.-Ft. ungt. It is also well combined with camphor as a dusting powder, or boracic acid in the treatment of purulent otitis of the external auditory meatus. BISMUTHI SUBCARBONAS (Bismuth Subcarbonate)—(Bi2OCO. H2O)—is recommended as a substitute for the subnitrate. It is thought to be more readily tolerated by the stomach, and is more soluble in the gastric juice, but it is less astringent. Dose, gr. v-xx, or even 3ss, in powder or pill. BISMUTHI ET AMMONII CITRAS (Bismuth and Ammonium Citrate), which occurs in glossy, translucent, colorless scales, of a slightly acid, metallic, but not disagreeable taste, very soluble in water, is a good preparation as an astringent. It is much more astringent than the insoluble preparations, but is more irritant; dose, gr.ij. The valerianate (not officinal) has been used in neuralgia; dose, gr. 1⁄2-j, several times a day, in pill. The test for a soluble salt of bismuth is a piece of paper wetted with a solution of potassium sulphocyanide, and dried, which will produce a yellow spot at the point of contact. CERII OXALAS-CERIUM OXALATE. This salt (Ce2(C2O4)3.9H ̧O) is usually made by adding a solution of ammonium oxalate to any soluble salt of cerium, and is obtained also from the mineral cerite. It occurs as a snow-white, |