Properties and Uses. - Hydragogue cathartic, diuretic; the strongest sodium purgative. When effloresced (dehydrated) it is twice as strong, hence dose should be only one-half. Largely used in veterinary practice, but for man is so harsh that magnesium sulphate almost always is substituted. Used in constipation, plethora, typhoid fever, dysentery, gastric ulcers, to neutralize phenol (carbolic acid) corrosion, to make sodium carbonate and glass. The bitter, nauseous taste may be overcome by flavoring with aromatic syrup, lemon, etc.

Sodii Phosphas. Sodium Phosphate, Na2HPO4 + 12H2O. - (Syn., Sod. Phos., Sodium Orthophosphate, Phosphas Sodicus (Natricus), Disodium Hydrogen Phosphate; Fr. Phosphate de Soude; Ger. Natrium phosphoricum, Natriumphosphat, Phosphorsaures Natron.)

Manufacture: Digest bone-ash with H2SO4, which forms acid calcium phosphate - Ca3(PO4)2 + 2H2SO4 = Ca(H2PO4)2 + 2CaSO4; filter, heat, add sodium carbonate to the solution, evaporate filtrate, crystallize - Ca(H2PO4)2 + 2Na2CO3 = 2Na2HPO4 + CaCO3 + H2O + CO2. It is in large, colorless, monoclinic prisms or granular, crystalline salt, odorless, cooling, saline taste, efflorescent, soluble in water (2.7), insoluble in alcohol; aqueous solution (1 in 10) alkaline; contains 39.25-44.00 p. c. of anhydrous sodium di-ortho-phosphate, corresponding to 99 p. c. of crystallized salt. Tests: 1. Heated above 40° C. (104° F.) - fuses, yielding colorless liquid; at 100° C. (242° F.) - loses all water of crystallization; at red heat - converted into sodium pyrophosphate. 2. Aqueous solution (1 in 20) with magnesia mixture T. S. - white, crystalline precipitate; produces intensely yellow flame. Impurities: Heavy metals, arsenic, calcium, aluminum, carbonate, chloride. Should be kept cool, in well-closed containers. Dose, alterative, gr. 20-40 (1.3-2.6 Gm.)purgative, 3ij-6 (8-24 Gm.).

Preparations. - 1. Soaii Phospnas Exsiccatus. Exsiccated Sodium Phosphate. (Syn., Sod. Phos. Exsic, Natrium Phosphoricum Exsic-catum, Dried (Anhydrous) Sodium Phosphate; Fr. Phosphate de Soude desseche; Ger. Getrocknetes Natriumphosphat.)

Manufacture: Allow sodium phosphate crystals 100 Gm. to effloresce several days in warm air at 25-30° C. (77-86° F.), continue the drying in an oven, gradually increasing the heat to 100° C. (212° P.), until salt ceases to lose weight; powder and sift. It is a white powder which absorbs moisture readily, soluble in water (8.1), boiling water (1.1), insoluble in alcohol; contains, when dried to constant weight, 9 p. c. of pure salt. Should be kept in well-closed containers. Dose, gr. 10-60 (.fr-4 Gm.).

Prep.: 1. Sodii Phosphas Effervescens. Effervescent Sodium Phosphate. (Syn., Sod. Phos. Eff., Natrium Phosphoricum Effervescens; Fr. Phosphate de Soude Effervescent; Ger. Brausendes Natriumphosphat.) Manufacture: Mix powdered citric acid 16.2 Gm., with exsiccated sodium phosphate 20 Gm., tartaric acid 25.2 Gm., then incorporate sodium bicarbonate 47.7 Gm.; heat in an oven at 93-104° C. (199-219° F.); when mixture moist from careful manipulation with wooden spatula, rub through No. 6 tinned-iron sieve, dry granules at 54° C. (130° F.). Should be kept in well-stoppered (sealed) containers. Dose, 3j-4 (4-15 Gm.). Unoff. Prep.: Liquor Sodii Phosphatis Compositus, official 1890-1910 - heat until liquefied sodium phosphate crystals 100 Gm., citric acid 13, add glycerin 15, water q. s. 100 Ml. (Cc), dose, 3 j - 2 (4 - 8 Ml. (Cc.)), in water (hot) 1 hour before meals.

Properties and Uses. - Hepatic stimulant, mild purgative, alterative, scrofula, rachitis, diabetes, scrofulous ophthalmia, bowel complaint, diarrhoea, jaundice, fevers.

Sodii Arsenas. Sodium Arsenate, Na2HAsO4 + 7H2O. - (Syn., Sod. Arsen.,Sodii Arsenias, Arsenias Natricus (Sodicus), Arseniate (Arsenate) of Soda; Fr. Arseniate de Soude; Ger. Natri-umarsenat (arsenicum), Arsensaurus Natron.)

Manufacture: Heat arsenic trioxide (10), sodium nitrate (8.5), and dried sodium carbonate (5.5) to redness, dissolve fused mass in water (35), crystallize - AS2O3 + 2NaNO3 + Na12CO3 = Na4As2O7 + N2O3 .+ CO2. Upon the addition of water to the warm mass, one molecule is combined, thereby converting the sodium pyroarsenate into the orthoarsenate, and as such crvstallizes upon standing - Na4-As2O7 + 15H2O = 2(Na2HAsO4, 7H2O). It is in colorless, transparent, monoclinic prisms; odorless, efflorescent, deliquescent, mild alkaline taste (use great care in tasting and then only in very dilute solutions), soluble in water (1.5), boiling water (1), slightly in alcohol, nearly insoluble in boiling alcohol; contains 58.98-61.92 p. c. of anhydrous sodium arsenate (di-sodium ortho-arsenate), corresponding to 99 p. c. of crystallized salt. Tests: 1. Heat gently - loses 5 molecules of water, being converted into a white powder; at higher temperature - loses all water

Fig. 454.   Sodium arsenate crystal.

Fig. 454. - Sodium arsenate crystal.

of crystallization; strongly heated - fuses, and at red heat - converted into pyroarsenate. Should be kept in well-closed containers. Dose, gr. 1/16-1/8 (.004-.008 Gm.).

Preparations. - 1. Sodii Arsenas Exsiccatus. Exsiccated Sodium Arsenate. (Syn., Sod. Arsen. Exsic; Br. Sodii Arsenas Anhydrosus; Natrium Arsenicum Exsiccatum, Dried (Anhydrous) Arsenate of Soda; Fr. Arseniate de Soude desseche; Getrocknetes Natriumarsenat.) Manufacture: Break into small fragments sodium arsenate crystals 100 Gm., allow them to effloresce at 40-50° C. (104-122° F.) until disintegrated, heat at 150° C. (302° F.) until product ceases to lose weight, pulverize. It is an odorless, amorphous, white powder, slightly hygroscopic, mildly alkaline taste (use great care in tasting and then only in very dilute solutions), soluble in water (3.1), boiling water (1.3), slightly in alcohol, nearly insoluble in boiling alcohol; contains when dried to constant weight, 98 p. c. of pure salt. Tests: 1. Aqueous solution (1 in 20) alkaline, produces intense yellow flame. 2. Aqueous solution with barium chloride T. S. - white precipitate, soluble in nitric acid; with silver nitrate T. S. - dark red precipitate, soluble in nitric acid. Impurities: Lead, copper, iron, arsenite. Should be kept in well-closed containers. Dose, gr. 1/24-1/12 (.0025-.005 Gm.).