What has been stated under potassium as to the influence of alkalies upon digestion and secretion applies equally to the alkaline salts of soda, but the chloride of sodium has a special value, perhaps from its furnishing in part the gastric acid; it aids the solution of albuminous substances, and increases the amount of saliva and gastric juice. Bar-deleben proved this by observations on dogs with gastric fistula, though, indeed, many other salts, and even mechanical irritants, will provoke a temporary increase in the gastric secretion. Rabuteau found that salted diet increased also the degree of its acidity, whether from irritation, or from the special properties of the chloride itself; certainly digestion suffers by its absence (Klein and Verson). The good effects are shown by small doses of 15 to 60 gr. Large quantities tend rather to coagulate albumen, while very large and concentrated doses cause vomiting, watery purging, and even gastritis: - in China, they are said to be used for suicidal purposes. Injection of much salt into the crural vein of dogs causes ptyalism, intestinal gurgling, and temporary lessening of the spleen (Podocaepow).

Different osmotic currents are determined by the different modes of administration; when either the chloride or sulphate of soda is injected into the blood, or taken in small quantities that can be quickly absorbed, constipation follows, while large amounts, given at one time, induce hyper-secretion and consequent purgation.

The action on bile-secretion is not certainly known: Nasse, experimenting with animals, found it lessened, but observations made after the use of alkaline waters show an increase (Grossmann), and this would be in accord with analogy. Rutherford has shown that sulphate of soda has marked cholagogue properties. According to Pavy, the carbonate not only increases the bile, but also the percentage of fat in the liver, and when introduced into the portal system causes the disappearance of hepatine, without formation of sugar (Guy's Reports, 1861, "Proc. Roy. Soc," vol. x.-xi., Medical Times, i., 1865): also the saccharine urine which commonly follows certain traumatic lesions of the sympathetic, does not occur if much soda be previously introduced into the blood; these are curious facts, of which we do not at present see the full bearing (cf. p. 301).

Circulatory System

It is an important difference between potash and soda, that the former is an active cardiac depressant and poison, while the latter has no definite effect on the heart-muscle or the circulation. Frogs, it is true, die, but only slowly, after the injection of very large quantities (Podocaepow, Guttmann), while upward of 100 gr. of soda carbonate have been introduced into the vein of a dog with but slight and temporary malaise and muscular weakness (Grandeau: Robin's Journal, 1864). Upon man, large doses seem to have but little effect in directly depressing the circulation.

The chloride of sodium, in small or moderate doses, increases the number of corpuscles; thus Plouviez had analyses made of his own blood before and after a course of salt, lasting two months, during which he took daily 150 gr. of salt besides his ordinary allowance, and at the end of the time the red globules were augmented 10 per cent., the fibrine was increased, the albumen diminished (Comptes Rendus, 1847, t. xxv.).

Rabuteau states that blood-corpuscles placed under the microscope disintegrate much less rapidly when salt is added than with simple water, and from this and general physiological results concludes that any influence of salt in apparently increasing the number of globules is exerted by conserving them, rather than by supplying food for fresh ones, as iron does.

According to Bergeret, omission of salt from a dietary leads to pallor, languor, oedema, and a chlorotic condition, the corpuscles are dissolved, and fibrine deposited (Abstract, Ranking, i., 1871; cf. p. 296), but on the other hand, the continued use of soda, as of any other alkali, lessens the number of red corpuscles and deteriorates the blood (Loffler, v. p. 270).

Whether the excessive use of highly salted food is the main cause of scorbutic conditions, such as occur in sailors and at whale-fisheries, may be considered doubtful; they may arise from the hardships of such life, from deficiency of potash, of vegetables, etc., but it would almost seem as if either great (relative) excess or deficiency of the element led to •equally injurious consequences. Prussac found that when frogs were placed in concentrated salt solutions or had them injected into the lymph sacs, copious "wandering" of red corpuscles took place from uninjured vessels, and also capillary hemorrhage (cf. p. 293).

External to the body, salt reddens and liquefies blood-clot. The change in color is attributed by Gubler to liberation of carbonic acid and absorption of oxygen by the haemoglobin. It is permanent, but I do not think it more than a physical change due to altered osmosis; it may be produced by many other saline compounds.

Soda is more abundant in the serum, while potash occurs most in the red globules, and excessive doses of the former alkali may alter this normal relationship, and thus interfere with respiratory combustion and with nutrition.

The proportion of sodium chloride in normal blood has been variously estimated at from 3 to 5 per 1,000. It is diminished in various morbid states, such as cholera, diabetes (Nasse), jaundice, chlorosis; in pneumonia, on the contrary, its elimination is checked, and hence an excess remains in the blood (Beale: Lancet, i., 1852; Bergeron: "These de Paris," 1866, and others).