2. Sodii Carbonas. Sodium Carbonate, Na2CO3 + 10H2O, official 1830-1900. Obtained by several processes: 1. Leblanc's: (1) 2NaCl + H2SO4 - Na2SO4 + 2HC1. (2) Na2SO4 + 4C + CaCO3 + heat = Na2CO3 + CaS + 4CO; the resulting mass (black-ash) is washed with water, thereby dissolving out the sodium carbonate. 2. Cryolite: This mineral is found in Greenland, being the double fluoride of aluminum and sodium. (1) Al2F66NaF + 6CaCO3 + heat = Al2O3 3Na2O + 6CaF, + 6CO2. (2) Al2O33Na2O + 3CO2 + 3H2O = 3Na2CO3 + 2Al(OH)3. The sodium aluminate is dissolved out by lixiviation with water, and into this solution CO2 is passed, under pressure, which, decomposing, precipitates aluminum hydroxide together with a little Na2CO3, while most of the pure Na2CO3 remains

Fig. 455. - Sodium thiosulphate crystal.

Fig. 456. - Sodium nitrate crystal.

in solution only to be crystallized out. 3. Solvays: (1) NaCl + 2NH3 + 2CO2 + 2H2O, under pressure = NaHCO3 + NH4HCO3 + MH4C1. (2) NH4HCO3 + NaCl = NaHCO3 + NH4C1. (3) 2Na-HCOa + heat = NaaCO3 + H2O + CO2. It is in colorless, monoclinic crystals, odorless, alkaline taste, effloresces, losing one-half of its water of crystallization (31.46 p. c. by weight), becoming a white powder.; soluble in water (1.6), glycerin (1.02), insoluble in alcohol, ether. Impurities: Iron, lead, arsenic, aluminum, ammonia, calcium, potassium, sulphates, chlorides, sulphite, hyposulphite, sulphocyanate. Should be kept in well-closed vessels. Dose, gr. 10-30 (.6-2 Gm.).

3. Sodii Carbonas Exsiccatus. Dried Sodium Carbonate, official 1830-1900. Obtained by exposing ordinary sodium carbonate 200 Gm., in broken crystals, for several days to warm air until effloresced and disintegrated; heat at 45° C. (113° F.) until reduced to 100 Gm. It is in loose white powder responding to reactions of monohydrated sodium carbonate. Dose, gr. 5 - 15 (.3-1 Gm.). Properties and uses of these two carbonates identical with that of the official salt.

4. Sodii Bisulphis. Sodium Bisulphite, NaHSO3, official 1880-1910. - Obtained by saturating a solution of sodium carbonate (bicarbonate) with SO2, crystallizing in a cool place - Na2CO3 + 2H2O + 2SO2 = 2NaHSO3 + H2O + CO2. It is in opaque, prismatic crystals, granular powder, odor of SO2, taste disagreeable, sulphurous; on exposure loses SO = SO2, becoming oxidized into sulphate; soluble in water (3.5), alcohol (70); strongly heated decrepitates; contains 90 p. c. of pure salt. Impurities: Heavy metals, thiosulphate. Checks putri-faction, fermentation, yeasty vomiting, aphthous sore throat, neutralizes chlorine in bleaching fabrics. Should be kept cool, in small, well-filled, well-stoppered containers. Dose, gr. 5-30 (.3-2 Gm.).

5. Sodii Chloras. Sodium Chlorate, NaClO3, official 1880-1910. - Obtained by adding sodium carbonate crystals (9) to tartaric acid (9.5) in solution (hot), add this to potassium chlorate (8) in solution - (1) Na2CO3+2H2C4H4O6 = 2NaHC4H4O6 + H2O + CO2. (2) NaHC4H4O6 + KC1O3 = NaClO3 + KHC4H4O6. It is in colorless, transparent crystals (regular cubes with tetrahedral facets) or a crystalline powder, odorless, cooling, saline taste, permanent, soluble in water (1), glycerin (5), alcohol (100), melts when heated, giving off oxygen (45 p. c. by weight), leaving a residue of sodium chloride; contains 99 p. c. of pure salt. Impurities: Lead, copper, potassium, etc. Same as potassium chlorate, only more soluble, and therefore may be used in more concentrated solution. Should be kept in well-stoppered containers, and handled cautiously, as dangerous explosions may occur if heated, subjected to concussion or trituration with organic substances (cork, tannin, sugar, sulphur, antimony sulphide, phosphorus, gambir, catechu, glycerin, etc.). Dose, gr. 5-15 (.3-1 Gm.).

Fig. 457. - Sodium chlorate crystal.

6. Sodii Pyrophosphas. Sodium Pyrophosphate, Na4P2O7 + 10H2O, official 1880-1910. - Obtained by heating sodium phosphate to dull redness - 2(Na2HPO4 + 12H2O) = Na4P20O7 + 25H2O. It is in colorless, transparent, monoclinic prisms, crystalline powder, odorless, cooling, saline, feebly alkaline taste, efflorescent in warm air, soluble in water (11.5), insoluble in alcohol, at 100° C. (212° F.) loses its water of crystallization (40.35 p. c.); contains in an uneffloresced condition 99 p. c. of pure salt. Impurities: Heavy metals, arsenic, carbonate, ortho-phosphate. Same as phosphate. Dose, 3j-4 (4-15 Gm.).

7. Sodii Santoninas. Sodium Santoninate, 2NaC15H19O4,7H2O, official 1880-1910. - Obtained by heating solution of sodium hydroxide 100 Ml. (Cc.), water 30 Ml. (Cc), santonin 30 Gm., until dissolved, filtering, crystallizing. It is in fine felt-like crystals (prisms), inodorous, saline, bitter, alkaline reaction; soluble in water (3), alcohol (12). Anthelmintic; lumbricoid worms. Should be kept dark, in amber-colored, well-stoppered vials. Dose, adult, gr. 5-10 (.3-.6 Gm.), twice daily; children, gr. 1-5 (.6-.3 Gm.), with sugar.

Li = 6.94.

The metal lithium (Gr.

a stone - i. e., dissolves these in the system, or is round among minerals) is not official, but has several salts which are. It is found sparingly as silicate in a few rare minerals, lepidolite, spodumene, amblygonite, etc., as chloride in soils and spring water, and as carbonate in plant ashes; it is the lightest metal known, resembles potassium and sodium, and, like them, ignites when thrown upon water.

Tests for Lithium Salts. - 1. The volatile salts give a vivid red to colorless flame. 2. Lithium compounds in strong solutions give with ammonium carbonate a white precipitate. 3. The neutral or alkaline solutions give with sodium phosphate, on boiling, a white precipitate (Li3PO4), soluble in acids and ammonium salts.