On reviewing what has been said respecting potash, we find that the chief actions and uses of its different salts may thus be briefly represented: Potassa Caustica - caustic. Liquor Potassae - antacid and stomachic. Potassae Bicarbonas, Carbonas, and Citras - antacid stomachics, alkalinisers of blood and urine, mild diuretics, very mild diaphoretics, saline expectorants, biliary stimulants. Potassae Tartras, Tartras Acida, and Acetas - the same, but more powerful diuretics; also saline purgatives. Potassae Sulphas - chiefly purgative. Potassae Nitras - excreted unchanged in the urine; is a double diuretic, and probably in this way only a mild febrifuge. Potassae Chloras - excreted unchanged in all the secretions, including the saliva; and is much used in inflamed, ulcerative, and aphthous states of the mouth. The remaining salts of potassium contain, in combination with the alkali, an element or acid possessing such distinctly specific actions that the total effect is but in a minor degree referable to the potash. Such are the arsenite, bromide, iodide, and permanganate, and sulphurated potash. These will, therefore, be discussed under the head of their other constituents.

The following are the officinal salts and preparations of sodium, arranged according to their source:

1. Sodae Carbonas

Sodae Carbonas. Carbonate of Soda. Na2CO3, 10H1O.

Source. - Made from the ashes of marine plants, or from chloride of sodium by chemical decomposition.

Characters. - Transparent colourless laminar rhombic crystals, efflorescent, with a harsh alkaline taste, and alkaline reaction. 20 gr. neutralise 9.7 gr. of citric acid, or 10 1/2 gr. of tartaric acid.

Impurities. - Sulphates and chlorides.

Dose. - 5 to 30 gr.

From Soda Carbonas are made: a.. Sodas Carbonas Exsiccata. - Dried Carbonate of Soda. Na2CO3. A dry white powder, made from Carbonate of Soda by drying. 53 gr. = 143 gr. of the crystallised salt. Dose, 3 to 10 gr.

b. Sodaa Bicarbonas. - Bicarbonate of Soda. NaHC03.

Source. - Prepared from a mixture of the Carbonate and Dried Carbonate by passing;a stream of carbonic acid gas through them; Na2CO3 + H1O + CO2 = 2(NaHCO3).

Characters. - A white powder, or small opaque irregular scales, of a not unpleasant saline taste. 20 gr. neutralise 167 gr. of citric acid, or 17.8 gr. of tartaric acid. 1 part soluble in 10 of water.

Impurities. - Carbonate and its impurities. Dose. - 10 to 60 gr.

Preparations.

a. Liquor Sodae Effervescens. - Soda Water. Made like potash water. 30 gr. in 1 pint. Dose, Ad libitum.

ß. Trochischi Sodae Bicarbonatis. - 5 gr. in each. Dose, 1 to 6. ^e^

γ. Sodae Citro - Tartras Effervescent - Effer-vescent Citro-tartrate of Soda. White granules, deliquescent; made by heating the Bicarbonate with Citric and Tartaric acids, stirring assiduously. Dose, 60 to 120 gr.

c. Liquor Sodae. - Solution of Soda. NaHO (4.1 per cent.) in water.

Source. - Prepared by boiling a solution of Carbonate of Soda with Slaked Lime. Na2CO3 + CaH1O2 = 2NaHO + CaCO3.

Characters. - A colourless alkaline liquid.

Impurities. - Lime, carbonates, sulphates, chlorides.

Dose. - (Rarely given) 10 min. to 1 fl.dr.

From Liquor Sodae are made: a. Soda Caustica. - Caustic Soda. NaHO. Source. - Made by boiling down Liquor Sodae. Characters. - Hard greyish-white fragments, slightly deliquescent, very alkaline. Impurities. - Same as of liquor.

ß. Sodae Valerianas, See Valeriana Radix.

d. Sodae Acetas. - Acetate of Soda. NaC2H3O2... 3H1O

Source. - Made by acting on Carbonate of Soda by Acetic Acid.

Characters. - Transparent colourless crystals. Used only to make ferri arsenias, ferri phosphas, and syrupus ferri phosphatis.

e. Soda Tartarata. - Tartarated Soda. NaK. C4H4O6.4H1O. Tartrate of soda and potash. Rochelle salt.

Source. - Prepared by boiling Acid Tartrate of Potash in a solution of Carbonate of Soda, and crystallising; Na2CO3 + 2KHC4H4O6 = 2NaK.C4H4O6 + H1O +CO2.

Characters. - Colourless transparent right rhombic prisms, tasting like common salt. Solubility, 1 in 2 of water.

Impurities. - Acid tartrate of potash.

Dose. - 1/4 to 1/2 oz.

f. Sodae Sulphas. - Sulphate of Soda. Glauber's salt. Na2SO4.10H1O.

Source. - Prepared by adding Carbonate of Soda to the acid sulphate left in the manufacture of hydrochlorici acid. Na2CO3 + 2NaHSO4 = 2Na2SO4 + CO2 + H1O.

Characters. - Colourless transparent oblique rhombic prisms, efflorescent, with a bitter salt taste. 1 part soluble in 3 of Water.

Impurities. - Salts of ammonium and iron.

Dose. - 1/4 to 1 oz.

g. Sodae Phosphas. - Phosphate of Soda. Na2HPO4. 12H1O

Source. - Prepared by adding a solution of Carbonate of Soda to the acid product of the action of sulphuric acid on bone-ash, and crystallising. (1) Ca32PO4 + 2H1SO4 = CaH42PO4 + 2CaSO4. (2) CaH42PO4 + Na2CO3 = Na2HP04 + CaHP04 + H1O + CO2.

Characters. - Colourless transparent rhombic prisms, efflorescent, tasting like common salt. 1 part soluble in 5 of water. Used to make ferri phosphas and syrupus ferri phosphatis.

Impurity. - Phosphate of lime.

Dose. - 1/4 to 1 oz.

h. Sodae Hypophosphis, - Hypophosphite of Soda. NaPH1O2.

Source. - Prepared by adding Carbonate of Soda to a solution of Hypophosphite of Lime, and evaporating the solution. Ca2PH1O2 + Na2CO3 = 2NaPH1O2 + CaCO3.

Characters. - A white granular deliquescent salt, with a bitter nauseous taste. 1 part soluble in 2 of water.

Dose. - 5 to 10 gr.

i. Sodas Arafinias. - Arseniate of Soda. Na2HAsO4. 7H1O.

Source. - Prepared by fusing Carbonate of Soda and Nitrate of Soda with Arsenious Acid, dissolving out and crystallising.

Characters. - Colourless transparent prisms. 1 part soluble in 2 of water.

Dose. - 1/16 to 1/8 gr.

Preparation. Liquor Sodae Arseniatis. - 4 gr. dried to 1 oz. water. Dose, 5 to 10 min.