On the kidneys soda acts less powerfully as a diuretic than potash, increasing the water and the solid constituents, and diminishing or neutralising the acidity of the urine. The bicarbonate is the most useful salt of soda for this purpose; the acetate and nitrate, whilst also diuretic, are so inferior to the acetate and nitrate of potash, that they are very seldom employed. The tartarated soda maybe usefully combined with other alkalinisers of the urine, as in the ordinary Seidlitz powder; and the effervescing citro-tartrate of soda is a convenient modification of much the same drugs. The use of these alkalinisers of the urine has been explained already.

The secretions of the bronchi are increased by soda; that is, the sputa become more abundant and more liquid, and are more easily expelled by cough. The bicarbonate and the chloride are specially expectorant, and are indicated in the early stages of bronchitis, and in recurrent slight bronchial catarrh, when secretion is deficient and cough harassing. The effects of soda on the stomach, blood, and urine add much to its usefulness in such cases. The stimulant effect of soda salts on ciliary action may also account in part for its expectorant action.

"When a comprehensive view is taken of the action and of the salts of soda - locally in the alimentary canal, in the blood, in the tissues, and in the organs and passages where it is excreted from the body, it is found to be peculiarly indicated in a condition of system which may be called the "gouty," the "rheumatic," "acidity," or "chronic derangement of the liver," and which is specially characterised, amongst other symptoms, by catarrhs, or discharges from the mucous membranes, interfering with the functions of the part; by imperfect biliary activity and constipation; and by scanty, high-coloured, very acid urine. In such a condition great benefit may be derived from a course of alkaline waters. If the stomach be the principal seat of catarrh, i.e. if chronic indigestion be urgent, the more purely carbonated alkaline waters should be selected, such as those of Vichy, Bilin, and Ems. If the derangement chiefly involve the liver and intestines, the sulphated and (NaCl) waters will be more suitable, such as Carlsbad, Kissin-gen, Wiesbaden, and Marienbad. For chronic catarrh of the bladder and urinary passages, Ems, Vichy, Wildungen, and Carlsbad are indicated.

5. Action And Uses Of The Different Soda Salts

The action and uses of the preparations of soda may be summarised as follows, and the special action of some of the salts particularly noticed: Soda Caustica and Liquor Sodae are for external use, but very rarely employed. Sodae Carbonas and Bicarbonas (the former rarely, the latter almost invariably used) possess the action and uses of soda in general upon all parts. Soda Citro-tartras is like the carbonates, but milder. Soda Tartarata is like the carbonates, but purgative; and more rapidly and distinctly diuretic and alkalinising, by virtue of the potash it contains. Sodae Acetas and Sodae Nitras are used pharmaceutically only. Sodae Sulphas and Sodae Phosphas are chiefly hydra-gogue purgatives and cholagogues, the former acting more on the bowels, the latter more on the liver. Sodii Chloridnm is in large doses a free and safe emetic; an anthelmintic as enema; it possesses otherwise the ordinary action of soda, and is greatly used for this purpose as the waters of Homburg, Wiesbaden, Kissingen, and Baden-Baden, and as sea-water. The remaining salts of soda possess peculiar properties by virtue of their second constituent, and are described elsewhere - Sodae Arsenias under Arsenic; Sodae Chlorates Liquor, under Chlorine; Sodae Hypo-phosphis under Phosphorus; Sodae Biboras under Acidum Boricum; Sodae Valerianas under Valerianae Radix.

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

1. Ammonii Chloridum

Ammonii Chloridum. Chloride of Ammonium. Muriate of Ammonia. Sal Ammoniac. NH4C1.

Source. - Made by neutralising Ammoniacal Gas Liquor with Hydrochloric Acid, and evaporating. NH4HO + HC1 = NH4C1 + H1O.

Characters. - Colourless translucent fibrous masses, inodorous and tough. Solubility, 1 in 4 of water; soluble in spirit.

Impurities. - Iron and lead.

Dose. - 5 to 20 gr.

From Ammonii Chloridum are made: a. Liquor Ammoniae Fortior. - Strong solution of Ammonia. NH3 (32.5 per cent.') in water.

Source. - Made by heating Chloride of. Ammonium with Slaked Lime, and collecting the gaseous product in water. 2NH4C1 + CaH1O2 = 2NH, + CaCl2 + 2H1O.

Characters. - A colourless liquid with a very pungent characteristic odour, and strong alkaline reaction.

Impurities. - Ammonium chloride, sulphide, and sulphate; lime, and metals. Detected by usual tests.

Preparations, a. Linimentum Camphorae Compositum..-Compound Liniment of Camphor. Strong solution of Ammonia, Camphor, Rectified Spirit, and Oil of Lavender; 1 in 4 1/2.

β. Liquor Ammonias Citratis. - Solution of Citrate of Ammonia. 3NH4.C6H5O7. dissolved in water. Made by adding Strong .Solution of Ammonia to a solution of Citric Acid.

Dose. - 2 to 6 fl.dr.

γ. Spiritus Ammoniae Aromaticus - Aromatic Spirit of Ammonia. Sal-volatile. Made by distilling a mixture of Strong Solution of Ammonia, Carbonate of Ammonia, Volatile Oil of Nutmeg, Oil of Lemon. Spirit, and Water.

Dose. - 1/2 to 1 fl.dr.

Spiritus Ammoniae Aromaticus is used in preparing Tinctura Guaiaci Ammoniata, and Tinctura Valerianae Ammoniata.

δ. Spiritus Ammonise Foetidus. - Fetid Spirit of Ammonia. Made by adding Strong Solution of Ammonia to an extract made from Assafoetida macerated in spirit.

Dose. - 1/2 to 1 fl.dr.

ε. Tinctura Opii Ammoniata. See Opium.