j. Sodae Chloratae Liquor. - Solution of Chlorinated Soda.

Source. - Made by passing a stream of Chlorine gas through a solution of Carbonate of Soda.

Characters. - A colourless liquid, with an odour of chlorine and an astringent taste; alkaline. A mixed solution of hypochlorite of soda, chloride of sodium, and carbonate of soda.

Dose. - 10 to 20 min.

Preparation. Cataplasma Sodae Chloratae.

2. Sodii Chloridum

Sodii Chloridum. Chloride of Sodium. Common salt. NaCl.

Source. - Native.

Characters. - Small white crystalline grains, or transparent cubic crystals, free from moisture, with purely saline taste. 1 part soluble in 2 3/4 parts of water.

Dose. - 10 to 240 gr.

Sodii Chloridum is used in making:

Acidum Hydrochloricum, Hydrargyri Perchlori-dum, and Hydrargyri Subchloridum.

3. Sodae Nitras

Sodae Nitras. Nitrate of Soda. NaNO3.

Source. - Native; purified by crystallisation from water. Characters. - Colourless obtuse rhombohedral crystals, with a cooling saline taste.

Impurities. - Sulphates and chlorides. Sodae Nitras is used in making: Sodae Arsenias.

4. Sodae Biboras

Sodae Biboras. Biborate of Soda. Borax. Na,B4O7.10H1O.

Source. - Native.

Characters. - Transparent colourless crystals, slightly efflorescent, weakly alkaline. 1 part soluble in 22 parts of cold water, or in 1 part of glycerine.

Dose. - 5 to 40 gr..

Preparations.

a. Glycerinium Boracis. - 1 to 4. p Mel Boracis. - 1 in 8.

Action And Uses. 1. Immediate Local Action And Uses

Externally, soda possesses an action similar to that of potash, hut is much less frequently used as a caustic. Solutions of the carbonates may he employed to neutralise caustic acids; in eczema and itching disorders of the skin; and in extensive burns. Soda compounds with olive oil constitute hard soap.

Internally. - Soda closely resembles potash in its action on the alimentary canal, but is more powerful because much less diffusible, i.e. more slowly absorbed. It is antacid to the contents of the stomach, relieving acidity due to indigestion, in the form either of the bicarbonates, soda-water, the officinal lozenges, or as a mixture with sal-volatile and an essential oil, such as peppermint, given after meals. As a stomachic, stimulating the flow of the gastric juice, bicarbonate of soda is more commonly given than the other alkalies, in doses of gr. 8 to gr. 15, shortly before meals. Part of the salt at the same time becomes converted into the chloride, which assists the digestion of albumen. The alkali also liquefies tenacious mucus, and thus prevents decomposition, the juice reaching the food more freely. Common salt is a safe and available emetic.

The salts of soda, being much less diffusible than those of potash, pass on into the small intestine. Here the sulphate and phosphate of soda and tartarated soda (Rochelle salt) act as saline purgatives. The sulphate, which is a constituent of several natural purgative waters, including Carlsbad, Friedrichs-hall, Hunyadi Janos, and Bilin, is the most powerful of these, producing an abundant watery evacuation. It is used as a hydra-gogue in dropsies, especially in ascites from liver disease, in congestion of the portal system, and as a habitual purgative The phosphate is a milder, but sufficiently active, purgative, less unpleasant to the palate; it is often given to children. Soda tartarata, the purgative basis of the Seidlitz powder, is familiar as a milder intestinal stimulant, of use in completing the effect of purgative pills. The chloride is an anthelmintic.

2. Action On The Blood And Its Uses

The salts of soda are slowly absorbed into the blood, and slowly excreted from it, remaining in it chiefly as the bicar-bonate and phosphate. Taken, as they constantly are, in food, these salts are the chief sources of the natural alkalinity of the liquor sanguinis, which may be increased by their medicinal exhibition as well as by the tartrate, Rochelle salt, and even the sulphate. This effect of soda as an alkaliniser of the blood is taken advantage of in the cases referred to under potash, namely, gout and rheumatism, only less frequently; for although soda is less depressing, as we shall see, than potash, and more easily borne on the stomach, the slowness of its entrance into the blood, and its tendency to pass off by the bowels when the dose is increased, more than counteract these advantages. When a prolonged and moderate alkaline influence is desired, especially in dyspepsia with a tendency to constipation, soda is manifestly to be preferred.

3. Specific Action

In medicinal doses, the salts of soda have no specific influence on any organ. This circumstance, which at first sight appears incredible, is due to the fact that the whole organism is saturated with soda, which participates in many of the ordinary tissue changes; that soda is admitted in large quantities by the food (especially vegetables and fruits); and that the moderate amount contained in medicinal doses does not appreciably affect metabolism. In this respect soda differs remarkably from potash, and is therefore said to produce none of the depressing effects of that drug. As we have just seen, advantage is taken of this negative action of soda in its therapeutical applications.

4. Remote Local Action And Uses

Soda is excreted by all the mucous surfaces, by the kidneys, by the liver, and possibly by the skin; and in passing through the various epithelial structures, it increases their activity, whilst it modifies the amount, composition, and reaction of their secretions. The action of the different salts naturally varies to a considerable extent, some affecting one organ more, some another. The sulphate and the phosphate of soda are, as we have seen, hydragogue purgatives by virtue of their immediate local action; but they are also stimulants of the intestinal glands, and are constantly being absorbed and excreted, reabsorbed and re-excreted, in their course along the bowel. (See Part III.) Both are also true hepatic stimulants or direct cholagogues; the phosphate more so than the sulphate. The value of these salts in hepatic and intestinal disorders, which has been already referred to, is therefore partly referable to their effect in increasing the bile. Soda tartarata has a similar but feebler action.