Baii - 137.37.

The element barium (L. bar(ytes)+ium, fr. Gr.

Barium 901

heavy, owing to high sp. gr. or heavy spar) and its compounds are not much used in medicine; it is found rarely in nature, and occurs then chiefly as sulphate (barite or heavy spar, BaSO4), also as carbonate (witherite, BaCO3). The metal fuses with difficulty, is of a silvery-gray color, decomposes water, oxidizes rapidly, sp. gr. 3.6. Salts are poisonous, but used sometimes in medicine as alterative, diuretic, cardiac tonic; cutaneous affections, scrofula; the sulphate employed to adulterate white lead, the nitrate in preparing green fire.

Tests for Barium Salts: 1. With H2SO4 or a soluble sulphate get white precipitate of barium sulphate, insoluble in all acids. 2. With alkaline carbonate get white precipitate, insoluble in excess. 3. With K2Cr2O7 get pale yellow precipitate of BaCrO4. 4. Gives yellowish-green color to flame.

Poisoning: Have salivation, thirst, vomiting, purging, abdominal pains, cramps, feeble pulse, dilated pupils, excessive urination, difficult breathing, spine paralysis, convulsions, collapse, death. Give emetics, magnesium or sodium sulphate (antidotes), albuminous drinks, diffusible stimulants, digitalis, opium, heat, etc.

Important Salts:

1. Barii Sulphas. Barium Sulphate, BaSO4, official 1830-1840. - This is. a native mineral (heavy spar) from which the other barium compounds are prepared. It is heavy, lamellar, brittle, sp. gr. 4.0, white or flesh-red. When heated decrepitates, melting into a white enamel (sulphide), which becomes a powder after some hours, insoluble in most solvents, therefore non-poisonous; soluble in excess of diluted hydrochloric acid. The artificial sulphate, made by precipitation from sulphide solution with diluted H2SO4, is known as permanent white or blanc fix, used for glazing cards, in water colors, and by painters instead of white lead.

2. Barii Carbonas. Barium Carbonate, BaCO3, official 1870-1880. - This is native witherite, found in lead mines in England, Scotland, Sweden. May be obtained artificially by precipitating a soluble barium salt with an alkali carbonate, or may fuse barium sulphate 10 parts, carbon 2, potassium hydroxide 5; wash the mass with water, thus leaving behind the carbonate - BaSO4 + C2 + 2KOH = BaCO3 + K2S + CO2 + H2O. It is in grayish fibrous masses or rhombic crystals, sp. gr. 4.5. If made artificially, it is a soft, white, amorphous or crystalline, tasteless powder. Impurities: Sulphate, lead, metals, alkalies, calcium. Other barium salts may readily be made by acting upon this salt with the respective acids; thus, nitrate - BaCO3 + 2HNO8 = Ba(NO3)2 + H2O + CO2, hydroxide - BaCO3 + 2KOH = Ba(OH)2 + K2CO3, also bromide, iodide, etc.

3. Barii Chloridum. Barium Chloride, BaCl2.2H2O, official 1870-1880. - Obtained by dissolving barium carbonate in diluted HC1, evaporating, crystallizing - BaCO3 + 2HC1 = BaCl2 + H2O + CO2; or (1) BaSO4 + C2 + white heat = BaS + 2CO2, (2) BaS + 2HC1 = BaCl2 + H2S. While the first method, in which the native carbonate is used, is the better, that salt is so scarce that the second formula is followed generally. It is in colorless, translucent, rhom-boidal tables or lamellae, permanent, soluble in diluted alcohol or water. Impurities: Carbonate, sulphate, lead, metals, alkalies, calcium, strontium chloride. Used only in making Liquor Barii Chloridi (10 Gm. + water q. s. 100 Ml. (Cc.)).

4. Barii Dioxidum. Barium Dioxide, BaO2, official 1890-1900. - Obtained by passing oxygen or air over barium oxide or hydroxide heated to redness. It is a heavy grayish or yellowish-white amorphous coarse powder, odorless, tasteless, nearly insoluble in water, forms salts with acids, slowly decomposes, absorbing H2O and CO2. Used only in making Liquor Hydrogenii Dioxidi.

The test-solutions of the carbonate, chloride, hydroxide, and nitrate are all used officially in assaying official salts, acids, etc.