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most simple is merely to procure the salt by a slow artificial evaporation. It then crystallizes with scarcely any mixture of the others. This is the cause of the superior purity of the bay-salt. Hence, also, the larger the crystals of sea-salt are, they may be justly supposed to be the purer, as the largeness of the crystals is owing to the slowness of the evaporation by which they are formed.

For chemical purposes, muriate of soda is most easily purified, by dissolving it in water, and adding to its solution a solution of carbonate of soda, drop by drop, till no cloudiness is produced by the addition. Every foreign salt is thus decomposed and precipitated, and the strained solution will contain the pure muriate of soda, which may be crystallized. Muriate of soda has a salt, rather agreeable taste, being, when pure, free from all bitterness; it is soluble in rather less than three parts of water, at the temperature of 60°. The crystals neither deliquesce, nor effloresce, on exposure to the air; the common sea-salt, indeed, is deliquescent; but this is owing to the muriates of magnesia and lime, which adhere to it. Exposed to heat, the crystals of muriate of soda decrepitate from the sudden conversion of their water of crystallization into vapour. If the temperature is raised to a red heat, the salt melts; in an intense heat, it is volatilized in white vapours, without having undergone any decomposition.

Crystallized muriate of soda contains 53 of soda, and 47 of acid, containing, however, some water of composition, so that of real acid, the quantity is 38.83. Its specific gravity is 2.12. This salt is decomposed by the sulphuric and nitric acids, in the same manner as the muriate of potash is. It is from its decomposition by the sulphuric acid, that the muriatic acid is best obtained, as has already been observed. When decomposed by the nitric acid, part of the latter is decomposed, a quantity of its oxygen being transferred to the muriatic. One of the most important practical problems in chemistry is to decompose this salt, so as to obtain its alkali. It abounds so much in nature, that if such a process, capable of being carried on to advantage, could be discovered, a vast supply of soda would be obtained; and as this alkali can be employed for every purpose that potash can, and is even much superior to it for some uses, such a discovery would be of much importance to the chemical arts. Salt is decomposed in the usual mode by sulphuric acid; and to

defray the expense, the muriatic acid is collected and employed in the manufacture of sal ammoniac, in the preparation of oxymuriatic acid for bleaching, or for any other useful purpose to which it can be applied. The sulphate of soda is calcined in a reverberatory furnace, to free it from any superfluous acid. It is then to be decomposed. It is of very extensive use. Its applica tion to preserve animal substances from putrefaction is well known; the theory of its antiseptic quality has never yet been properly explained. It is also taken universally as a seasoning to food, and seems to be very necessary to promote digestion, as even the lower animals, it has been proved, languish when altogether deprived of it. It is employed in a variety of arts. In the manufacture of pottery of the coarser kind, when it is thrown into the oven in which the ware is baked, it is converted into vapour, and, being applied in this state to the surface of the vessels, glazes them, an effect probably owing to the combination of its alkali with the siliceous earth of the pottery. It is employed in the manufacture of glass, which it is said to render whiter and clearer; in that of soap, which it makes harder; as a flux, in the melting of metals from their ores; and in a variety of chemical and pharmaceutical processes.

SALT, in a chemical sense, is a chrystallizable substance, considerably soluble in water, and highly sapid. The term is ap plied likewise by modern chemists to all the crystallizable acids, or alkalies, or earths, or combinations of acids with alkalies, earths, or metallic oxides: hence salts in chemistry are distinguished into alkaline, earthy, and metallic, and they take their names from the acid, and alkali, &c. of which they are combined: thus the sulpháte of soda is a combination of sulphuric acid and soda; the sulphite of soda is a combination of sulphurous acid and soda. The termination ate denotes that the salt is formed of the acid containing the greater quantity of oxygen, and the termination ite of the acid, containing the smaller quantity of oxygen. There are also salts of triple combinations, as alum, tartarized antimony, &c. Salts are either also neutral, that is where the ingredients are in perfect saturation, (see NEUTRALIZATION,) or with the acid in excess, of which tartar is an example, or with an excess of the base, as in borax. These circumstances have been distinguished by the prefix super in the first case, and sub in the latter: hence tartar is

named the super-tartrite of potash; and borax, the sub-borate of soda.

SALVADORA, in botany, a genus of the Tetrandria Monogynia class and order. Natural order of Atriplices, Jussieu. Essential character: calyx four-cleft; corolla four-cleft; berry one-seeded; seed covered with an aril. There are three species found in China.

SALVAGE money, a reward allowed by the civil and statute law, for the saving of ships or goods from the danger of the seas, pirates, or enemies. Where any ship is in danger of being stranded, or driven on shore, justices of the peace are to command the constables to assemble as many persons as are necessary to preserve it; and on its being preserved by their means, the persons assisting therein shall, in thirty days after be paid a reasonable reward for the salvage, otherwise the ship or goods shall remain in the custody of the officers of the customs, as a security for the same.

SALVIA, in botany, sage, a genus of the Diandria Monogynia class and order. Natural order of Verticillata. Labiata, Jussieu, Essential character: corolla unequal; filaments fastened transversely to a pedicle. There are seventy-nine species. This extensive genus consists of herbs or under shrubs; the flowers are from one to three together from a bracte, or a leaf, frequently in spikes. S. officinalis, or common large sage, which is cultivated in gardens, of which there are the following varieties: 1. The common green sage. 2. The wormwood sage. 3. The green sage with a variegated leaf. 4. The red sage. 5. The red sage with a variegated leaf. These are accidental variations, and therefore are not enumerated as species. The common sage grows naturally in the southern parts of Europe, but is here cultivated in gardens for use but the variety with red or blackish leaves is the most common in the British gardens and the wormwood sage is in greater plenty here than the common greenleaved sage, which is but in few gardens. S. auriculata, common sage of virtue, which is also well known in the gardens and markets. The leaves of this are narrower than those of the common sort; they are hoary, and some of them are indented on their edges towards the base, which indentures have the appearance of ears.

SALVINIA, in botany, a genus of the Cryptogamia Miscellanea class and order. Generic character: male, flowers four to nine, among whorled roots, heaped into a

little ball; calyx sub-globular, pubescent, one-celled, consisting of a double mem. brane; corolla none, unless it be the inner membrane of the calyx; stamen an up right pillar, placed on the base of the calyx: female, in the middle of the ball, solitary; calyx and corolla as in the males; pistils; germs about fifteen, obliquely ovate, blunt, rugged with dots, each on distinct pedicles, fastened to the bottom of the calyx; style none; stigma a dot on the top of the germ; pericarpium none; seeds as many as there are germs, and of the same form. The male and female flowers may be distinguished in the dry plant before the calyxes open, by the size of the protuberant grains. SALUTATION, the act of saluting, greeting, or paying respect and reverence to any one. There is a great variety in the forms of salutation. The orientals salute by uncovering their feet, laying their hands on their breasts, &c. In England, we saInte by uncovering the head, bending the body, &c. The pope formerly paid reverence to none except the emperor, to whom he stooped a very little, when he permitted him to kiss his lips. A prince, or person of extraordinary quality, is saluted at his entering a garrison by the firing of the cannon round the place. In the field, when a regiment is to be reviewed by a king, or his general, the drums beat as he approaches, and the officers salute him one after another, as he passes by, stepping back with the right foot and hand, bowing their half pikes to the ground, and then recovering them gently, bringing up the foot and hand, and planting them; which done, they pull off their hats without bowing. The ensigns salute all together, bringing down their colours near the ground directly before them at one motion, and having taken them up again, gently lift their hats. At sea, they salute by a discharge of cannon, which is greater or less, according to the degree of respect they would show ; and here ships always salute with an odd number of guns, and galleys with an even one. To salute with muskets is to fire one, two, or three vollies; which is a method of salutation that sometimes precedes that of cannon, and is chiefly used on occasion of feasts. After the cannon, they also sometimes salute or hail with the voice, by a joint shout of all the ship's company, repeated three times; which salutation also occasionally obtains where they carry no guns, or do not care to discharge any. Saluting with the flag is performed two ways,

either by holding it close to the staff so as it cannot flutter, or by striking it so as it cannot be seen at all, which is the most respectful. Saluting with the sails is per-, formed by hovering the topsails half-way of the masts. Only those vessels that carry no guns salute with the sails.

The following regulations on this subject are deserving of notice: "When any of his Majesty's ships shall meet with any ship or ships belonging to any foreign prince or state, within his Majesty's seas, (which extend to Cape Finisterre) it is expected that the said foreign ships do strike their topsail, and take in their flag, in acknowledg. ment of his Majesty's sovereignty in those seas: and if any shall refuse, or offer to resist, it is enjoined to all flag-officers and commanders to use their utmost endeavours to compel them thereto, and not suffer any dishonour to be done to his Majesty. And if any of his Majesty's subjects shall so much forget their duty, as to omit striking their top-sail in passing by his Majesty's ships, the name of the ship and master, and from whence, and whither bound, together with affidavits of the facts, are to be sent up to the Secretary of the Admiralty, in order to their being proceeded against in the Admiralty Court. And it is to be observed, that in his Majesty's seas, his Majesty's ships are in no wise to strike to any; and that in no other parts, no ship of his Majesty is to strike her flag or topsail to any foreigner, unless such foreign ship shall have first struck, or at the same time, strike her flag or top sail to his Majesty's ship. The flag-officers and commanders of his Majesty's ships are to be careful to maintain his Majesty's honour upon all occasions, giving protection to his subjects, and endeavouring, what in them lies, to secure and encourage them in their lawful commerce; and they are not to injure, in any manner, the subjects of his Majesty's friends and allies."

SAMARA, in botany, a genus of the Tetrandria Monogynia class and order. Natural order of Rhamni, Jussieu. Essential character: calyx four-parted; corolla four-petalled; stamina immersed in the base of the petal; drupe one-seeded. There are four species.

SAMBUCUS, in botany, elder, a genus of the Pentandria Trigynia class and order. Natural order of Dumosæ. Caprifolia, Jussieu. Essential character: calyx five parted; corolla five-cleft; berry three-seeded, There are five species.

SAMIELS, the Arabian name for a hot

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suffocating wind peculiar to the desert of Arabia. It blows over the deserts in the months of July and August from the northwest, and sometimes it continues its progress to the very gates of Bagdad, but it is said never to affect any person within the walls. It often passes with the quickness of lightning: and there is no way of avoiding the dire effects but by falling on the ground, and keeping the face close to the earth. Those who are negligent of this caution experience instant death.

SAMOLUS, in botany, a genus of the Pentandria Monogynia class and order. Natural order of Precia. Lysimachiæ, Jussieu. Essential character: corolla salver-shaped; stamina fenced by the scalelets of the corolla; capsule one-celled, inferior. There is but one species; riz. S. valerandi, brookweed or water pimpernel; this plant is an inhabitant of every quarter of the globe, in marshes, wet meadows, and ditches; Mr. Miller considers it as an annual; Linnæus marks it as biennial; and others as perennial.

SAMYDA, in botany, a genus of the Decandria Monogynia class and order. Essential character: calyx five-parted, coloured; corolla none; nest bell-shaped, staminiferous; capsules berried within, fourvalved, one-celled; seeds nestling. There are nine species,

SAND, in natural history, a genus of fossils, the characters of which are, that they are found in minute concretions; forming together a kind of powder, the genuine particles of which are all of a tendency to one determinate shape, and appear regular, though more or less complete concretions; not to be dissolved or disunited by water, or formed into a coherent mass by means of it, but retaining their figure in it; transparent, vitrifiable by extreme heat, and not dissoluble in, nor effervescing with, acids. See SAND-STONE.

Sand is of great use in the glass manufac ture; the white writing sand being employed for making of the white glass, and a coarse greenish-looking sand for the green glass. In agriculture it seems to be the office of sands to make unctuous earths fertile, and fit to support vegetables, &c. For earth alone, we find, is liable to coalesce, and ga. ther into a hard coherent mass, as appears in clay; and being thus embodied, and as it were glued together, is no way disposed to nourish vegetables.

Common sand is a very good addition, by way of manure, to all sorts of clay-lands; it warms them, and makes them more open

and loose. The best sand for the farmer's use is that which is washed by rains from roads or bills, or that which is taken from the beds of rivers; the common sand that is dug in pits never answers nearly so well. However, if mixed with dung, it is much better than laid on alone and a very fine manure is made by covering the bottom of sheep-folds with several loads of sand every week, which are to be taken away, and laid on cold stiff lands, impregnated as they are with the dung and the urine of the sheep.

Beside clay-land there is another sort of ground very improveable by sand; this is that sort of black boggy land on which bushes and sedge grow naturally, and which they cut into turf, in some places. Six hundred load of sand being laid upon an acre of this land, according to the Cheshire measure, which is near double the statute acre, meliorate it so much, that without ploughing it will yield good crops of oats or tares, though before it would have produced scarcely any thing. If this crop is taken off, the land will be well dunged, and if then, laid down for grass, it will yield a large crop of sweet hay.

Once sanding this land will improve it for a vast number of years, and it will yield two crops of hay in the year, if there be weather to make it in. Some land in Cheshire has been, by this means, rendered of twelve times its former value to the owner. The bogs of Ireland, when drained, have been rendered very fruitful land, by mixing sand in this manner among the earth, of which they consist. Add to this, that in all these boggy lands, the burning them, or firing their own turf upon them, is also a great advantage. The common peat, or turfashes, mixed with the sand for these purposes, add greatly to its virtue. Sea-sand, which is thrown up in creeks and other places, is by much the richest of all sand for manuring the earth; partly its saltness, and partly the fat and unctuous filth that is mixed among it, give it this great virtue. In the western parts of England, that lie upon the sea coast, they make very great advantages of it. The fragments of seashells also, which are always in great abundance in this sand, add to its virtues; and it is always the more esteemed by the farmers, the more of these fragments there are among it.

The sea-sand, used as manure in different parts of the kingdom, is of three kinds : that about Plymouth, and on other of the southern coasts, is of a blue-grey colour, like

ashes, which is probably owing to the shells of muscles, and other fish of that or the like colour, being broken and mixed among it in great quantity. Westward, near the Land's End, the sea-sand is very white, and about the isles of Scilly it is very glistening, with small particles of tale; on the coasts of the North Sea, the sand is yellowish, brown, or reddish, and contains so great a quantity of fragments of cockle-shells, that it seems to be chiefly composed of them. That sea sand is accounted best which is of a reddish colour: the next in value to this is the bluish, and the white is the worst of all. Sea-sand is best when taken up from under the water, or from sand-banks, which are covered by every tide. small grained sand is most sudden in its operation, and is therefore best for the te nant who is only to take three or four crops; but the coarse or large grained sand is much better for the landlord, as the good it does lasts many years.

The

SAND bags, in the art of war, are bags filled with earth or sand, holding each about a cubic foot their use is to raise parapets in haste, or to repair what is beaten down.

SAND flood, a terrible mischief, incident to the lands of Suffolk, and some other parts of England; which are frequently covered with vast quantities of sand, rolling in upon them like a deluge of water, from sandy hills in their neighbourhood.

The flowing of sand, though far from being so tremendous and hurtful as in Arabia, is of very bad consequences in this country, as many valuable pieces of land have thus been entirely lost; of which we give the following instances from Mr. Pennant, together with a probable means of preventing them in future. "I have more than once," says he, " on the eastern coasts of Scotland, observed the calamitous state of several extensive tracts, formerly in a most flourishing condition, at present covered with sands, unstable as those of the deserts of Arabia. The parish of Furvic, in the county of Aberdeen, is now reduced to two farms, and above 500l. a year lost to the Errol family, as appears by the oath of the factor in 1600, made before the Court of Session, to ascertain the minister's salary. Not a vestige is to be seen of any buildings, unless a fragment of the church. The estate of Coubin, near Forres, is another melancholy instance. This tract was once worth 3001, a year, at this time overwhelmed with sand. This strange inundation was still in motion in 1769, chiefly when a strong

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wind prevailed. Its motion is so rapid, that I have been assured, that an apple-tree had been so covered with it in one season, that only the very summit appeared. This distress was brought on about ninety years ago, and was occasioned by the cutting down some trees, and pulling up the bent or star which grew on the sand-hills; which at last gave rise to the act of 15 George II. c. 33, to prohibit the destruction of this useful plant.

"I beg leave to suggest to the public a possible means of putting a stop to these destructive ravages. Providence hath kindly formed this plant to grow only in pure sand. Mankind was left to make, in after times, an application of it suitable to their wants. The sand-hills on a portion of the Flintshire shores, in the parish of Llanasa, are covered with it naturally, and keep firm in their place. The Dutch perhaps owe the existence of part, at least, of their country to the sowing of it on the mobile solum, their sand-banks. My humane and amiable friend, the late Benjamiu Stillingfleet, Esq. recommended the sowing of this plant on the sandy wilds of Norfolk, that its matted roots might prevent the deluges of sand which that country experiences. It has been already remarked, that wheresoever this plant grows the salutary effects are soon observed to follow. A single plant will fix the sand, and gather it into a hillock; these hillocks, by the increase of vegetation, are formed into larger, till by degrees a barrier is made often against the encroachments of the sea, and might as often prove preventative of the calamity in question. I cannot, therefore, but recommend the trial to the inhabitants of many parts of North Britain. The plant grows in most places near the sea, and is known to the Highlanders by the name of murah; to the English by that of bent-star, matgrass, or marram. Linnæus calls it arundo arenaria. The Dutch call it helm. This plant hath stiff and sharp-pointed leaves, growing like a rush, a foot and a half long the roots both creep and penetrate deeply into their sandy beds: the stalk bears an ear five or six inches long, not unlike rye; the seeds are small, brown, and roundish. By good fortune, as old Gerard observes, no cattle will eat or touch this vegetable, allotted for other purposes, subservient to the use of mankind."

SAND stone, in mineralogy, is chiefly composed of quartz in rounded grains of various izes, Sand-stones are stratified, and when

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disintegrated they form sand. We have many varieties; as, 1. "The calcareous sand-stone," which is of a green or greyish colour: it is moderately hard, and gives sparks when struck against steel. It effervesces with acids: when freed from the calcareous cement there remains a very friable mass of fine white sand. 2. "The ferruginous sand-stone," which is of a reddish brown: it is opaque and soft, and seldom effervesces with acids: it readily disintegrates by exposure to the weather. 3. "Grit-stone," which rarely effervesces with acids, but gives very lively sparks when struck with the steel. It is not easily decomposed by exposure to the air. Sandstone is applied to many important purposes in building; as flag-stones: and the harder kinds of grit-stone are made into grindstones, and on account of their infusi bility they are employed for lining fur

naces.

SANDARACH. See RESIN.

SANDARACH, in natural history, a very beautiful native fossil, though too often confounded with the common factitious red arsenic, and with the red matter formed by melting the common yellow orpiment. It is a pure substance, of a very even and regular structure, is throughout of that colour which our dyers term an orange-scarlet, and is considerably transparent even in the thickest pieces. But though with respect to colour it has the advantage of cinnabar while in the mass, it is vastly inferior to it when both are reduced to powder. It is moderately hard, and remarkably heavy; and when exposed to a moderate heat, melts and flows like oil. If set on fire it burns very briskly.

It is found in Saxony and Bohemia, in the copper and silver mines, and is sold to the painters, who find it a very fine and valuable red; but its virtues or qualities in medicine are no more ascertained at this time than those of the yellow orpiment.

SANDORICUM, in botany, a genus of the Decandria Monogynia class and order. Essential character: calyx five-toothed, petals five; nectary cylindrical, truncate, bearing the anthers at its mouth; drupe filled with five nuts. There is only one species, viz. S. indicum, a native of the Philippine and Molucca islands.

SANGUINARIA, in botany, a genus of the Polyandria Monogynia class and order. Natural order of Rhoeadeæ, Papaveraceæ, Jussien. Essential character: calyx twoleaved; corolla eight-petalled; silique ovate,

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