Vel Marinus Sal, (from mare the tea). Sea salt; esebon; communis, culinarius, et ci-barius sal; common salt.
The salt is not only extracted from the sea water by evaporation, but is also found in extensive strata. (See Gemma sal.) It is composed of the marine acid, and the mineral alkali; dissolves in about thrice its weight of cold water, though, when heated, it scarcely requires less.
The solution of this salt, if gently evaporated, affords cubical crystals, which are the common or alimentary salt. A small quantity of the sal catharticum amarum is next produced; but the chief part of this salt remains in what is called the mother water, which is oily, and on that account will not admit of its farther crystallization. Common salt, when dried in the temperature of 80°, contains 38.88 of acid, 53 of soda, and 8.12 of water: by others the acid is said to be 33.3, and the alkali 50. Its specific gravity is 2.120; it decrepitates in the fire, renders water colder than before, though, from the addition, it is more difficult to freeze. Common salt is the most generally useful condiment, and the best antiseptic to preserve meat from putrefaction, and butter from rancidity. It furnishes a firm and cheap glazing for earthen ware, and is of considerable use in the process of dying. The separation of soda from sea salt is a problem of considerable importance in the arts; and it has been completely solved, if the removal of the duty on salt would render it practicable with advantage. This is not the place for disquisitions not connected with medicine; but we may remark, that iron, litharge and lime, in proper circumstances, will effect the decomposition. The lime in the soil of Egypt and Tripoli seems the means by which the soda has been separated in such considerable quantities. Acetite of lead will equally effect the separation of the alkali; but it is too dear for commercial purposes. In the animal economy common salt is of general utility. (See Condiments.) It seems to check putrefaction; but is of more service as a general stimulant. Animals pine when deprived of it, and few nations have been found who have not added this condiment to their food. In the animal process the fixed alkali is seemingly changed to the volatile, and we have suspected that the muriatic acid is changed to the phosphoric. Chemistry has not yet elucidated this subject, and we offer it chiefly as a conjecture which we could support by inductive reasoning, were this the place for such disquisitions. Beyond its general stimulus we do not perceive any salutary action of sea salt in the proportion usually taken. In large quantities it is used as an emetic, as a remedy for haemorrhage from the lungs, and in the form of sea water as a laxative and a remedy for scrofula. (See Haemoptysis and aqua marina.) Externally it is used in palsies, and in apparent death from drowning. In these cases, as in almost every other, it seems to act as a simple stimulus only.
The sea water, gradually evaporated by the sun's heat, on the rocks, or in circuitous canals made for this purpose, is called bay salt, and is formed into large crystals; it does not liquefy in a moist air, and is more powerfully antiseptic.
Spiritus salis marini Glauberi, or the muriatic acid, is made by gradually adding six pounds of vitriolic acid, mixed with five pounds of water to ten pounds of dry sea salt: the acid is then separated by distillation. In this state the acid comes over in a gaseous form, and requires condensation by means of water. As a gas it is elastic and invisible, incapable of supporting animal life or flame, has a pungent smell, and acid taste, and a specific gravity nearly of .002315, about double that of common air. Water absorbs it copiously and freely; but it is unchanged by the strongest light and heat. Ice absorbs it also, but boiling water admits of no union with it. In the process just described, the acid of vitriol unites with the mineral akali, leaving its acid free, which rises in distillation; and, in the usual form, that of a colourless or a pale yellow fluid: its specific gravity is 1.196, though the acid of commerce is seldom more than 1.17. The strongest liquid acid is supposed by Mr. Kirwan to contain about an equal part of water. The dryest gas contains a small portion of water, which is only separated by electrical explosions.
The specific gravity directed by the college is to that of distilled water, 1.170, to 1000.
The muriatic is the weakest of the mineral acids, but
6 A2 stronger than any of the vegetable kind: it requires a greater fire to distil it than that of nitre, yet it is more readily dissipated by the action of the air. It has no effect on oxygen gas or inflammables. The muriatic acid oxidates metals, but requires for all, except iron, a greater or less degree of heat. It combincs with all alkalis, earths, and the greater number of metallic oxides.
Its composition (see Chemistry) is not yet ascertained. The latest experiments are those of M. Brug-rtatelli, in the sixty-second volume of the Journal de Physique, p. 298. He certainly found the muriatic acid produced, when the galvanic fluid was passed through water, by means of gold, platina, iron, or the black oxide of manganese; but some other metals, particularly silver, produced, in the water, soda. We can connect this only with one fact, that water, evaporating from iron, produces a positive electricity, and from silver a negative. In these experiments of De Saussure it is, however, clear that the water is decomposed rather than evaporated. In Brugnatelli's experiments the positive pole seemed to produce in the decomposition of the water the acid, and the negative the soda.
It is chiefly used as a tonic and antiseptic, in the dose of from ten to sixty drops, in water, or any other convenient liquid. In putrid fevers, after having cleansed the primae viae, it supports the strength, and corrects any remaining putrefaction on the contents of the stomach and bowels; but seems not to carry its antiseptic quality into the general mass, which indeed is seldom in a putrid state. It was Recht's boasted remedy for fevers, which the Prussian government bought at a considerable price. In bilious fevers it has been recommended; but it is not peculiarly useful, and, in general, its good effects are confined to the parts in immediate contact with it.
In acidulated gargles for ulcerated throats it has been strongly recommended, but seems to be in no respect superior to the vitriolic acid; and; diluted with the tincture of benzoe, has been applied, it is said, with success to putrid ulcers.
Linnaeus remarks, that, if properly diluted, and applied to chilblains, it radically cures them. If half an ounce of good bay salt is dissolved in four ounces of water, and two drachms of the muriatic acid be added, it will form a mixture, of which a tea spoonful, in a glass of water, is said to improve the appetite, and frequently stop vomiting.
The muriatic acid, combined with volatile alkalis, produces the officinal sal ammoniac; with fixed vegetable alkali the sal digestivus Sylvii; in modern language, muriated potash. See Chemistry.
The acidum muriaticum, combined with calcareous earths, forms a calcareous muriat, which deliquates in the air, and dissolves both in water and in rectified spirit of wine. It is contained in a considerable quantity in sea water, but remains in the mother water after the crystallization of the muriated soda, and is said to be antiseptic, diuretic, and lithontriptic. The medicine, commonly sold under the name of liquid shell, appears to consist only of calcined shells dissolved in marine acid. These combinations are made by mixing the calcareous earth with sal ammoniac, and urging the mixture with a gradual fire, until the volatile alkali of the salt is either dissipated or collected by subiimation when the acid unites with the earth.
The muriat of lime has lately become a fashionable remedy in scrofula, in scirrhi, and other diseases supposed to arise from inspissated lymph. From half a drachm to half an ounce, diluted with water, is given, according to circumstances, every day.
See Lewis's Materia Medica; Neumann's Chemical Works.