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Excess of silica gives a glass or porcelain, but excess of alumina will not furnish a glass. When, in mixtures of magnesia, silica, and alumina, the first is in excess, no fusion takes place at, 150°; when the second exceeds, a porcelain may be formed: and 3 parts of silica, 2 magnesia, and 1 alumina, form a glass. From Achard's experiments it would appear that a glass may be produced by exposing to a strong heat, equal parts of alumina, silica, lime, and magnesia. Other proportions gave fusible mixtures, provided

the silica was in excess.

The mineral sommite, or nephelin, consists, according to Vauquelin, of 49 alumina + 46 silica. If we suppose it to consist of a prime equivalent or atom of each constituent, then that of silica would be 3; for 49:32:46:3. But, if we take Vauquelin's analysis of euclase for the same purpose, we have the proportion of silica to that of alumina as 35 to 22. Hence 22:32 :: 35: 5.09 the prime equivalent of silica, which is not reconcileable to the above number, though it agrees with that deduced from Sir H. Davy's experiments on silicon. I give these examples to show how unprofitable such atomical determinations are. See IRON and ACID (FLUOSILICIC). SILICENSE, in ancient geography, a river of Spain.

SILICIOUS, adj. Lat. cilicium, it should be therefore written cilicious. Made of

hair.

The silicious and hairy vests of the strictest orders of friars derive their institution from St. John and Elias. Browne.

SILICERNIUM (from silex and cœna, a supper on a stone), among the Romans, a feast of a private nature, provided for the dead some time after the funeral. It consisted of beans, lettuces, bread, eggs, &c. These were laid upon the tomb, and they foolishly believed that the dead would come out for the repast. What was left was generally burnt on the stone. Eating what had thus been provided for the dead was esteemed a mark of the most miserable poverty. A similar entertainment was made by the Greeks at the tombs of the deceased; but it was usual among them to treat the ghosts with the fragments from the feast of the living. See FUNERAL, and

INFERIE.

SILICIS MONS, in ancient geography, a town of Italy, near Padua, on a mountain so named. SILIQUOSE, adj. Į Lat. siliqua. Having SIL'IQUOUS. Sa pod or capsula.

All the tetrapetalous siliquose plants are alkalescent. Arbuthnot.

SILIS, in ancient geography, a river of Italy, in Venetia.-Plin. iii. c. 18.

SILISTRIA, or DRISTRA, a large town in Bulgaria, European Turkey, situated on the Danube, on its south bank, at the influx of the Missova. It is well fortified, tolerably built, and has several handsome mosques and baths. Being VOL. XX

out of the usual road from Turkey to Germany, it is rarely visited; but in the environs are to be seen the ruins of the wall erected by the Greek emperors. It is one of the most important frontier towns of Turkey; and in 1773 several sharp actions took place here with the Russians. It is the see of an archbishop. Population 20,000. 155 miles N. N. E. of Adrianople. Long. 27° 6' E., lat 44° 15' N.

SILIVRI, or SELIVREA, the ancient Selymbria, a sea-port of Turkey, in Romania, on the western side of a promontory, near the sea of Marmora. It contains 6000 inhabitants, of whom 1500 are Greeks, and 200 Jews, and commands a beautiful prospect of the Propontis. Thirty-two miles west of Constantinople.

SILIUS ITALICUS (Caius), an ancient Roman poet, and author of an epic poem in seventeen books, containing a history of the second Punic war, which decided the empire of the world in favor of the Romans. He was born in the reign of Tiberius, and is supposed to have got the name of Italicus from the place of his birth; but whether he was born at Italica in Spain, or at Corfinium in Italy, which, according to Strabo, had the nane of Italica given it during the Social war, is a point which cannot be known: though if his birth had happened at either of these places, grammarians justly observed, he should have been called Italicensis, and not Italicus. When he came to Rome he applied himself to the bar; and, by a close imitation of Cicero, succeeded so well that he became a celebrated advocate, and most accomplished orator. His merit and character recommended him to the highest offices in the empire, even to the consulship, of which he was possessed when Nero died. He is said to have been aiding and assisting in accusing persons of high rank and fortune whom that wicked emperor had devoted to destruction: but he retrieved his character afterwards by a long and uniform course of virtuous behaviour. Vespasian sent him as proconsul into Asia, where he behaved with clean hands and an unblemished reputation. After having thus spent the best part of his life in the service of his country, he bade adieu to public affairs, resolving to consecrate the remainder to polite retirement and the Muses. He had several fine villas in the country: one at Tusculum, celebrated for having been Cicero's; and a farm near Naples, said to have been Virgil's, at which was his tomb, which Silius often visited. Thus Martial compliments him on both these accounts (Epig. 49, lib. xi.); and politely concludes,

Could those great shades return to choose their heir, The present owner they would both prefer. In these retirements he applied himself to poetry: led not so much by force of genius as by his exceeding great veneration for Virgil. He has imitated him in his poen; and, though he falls far short of him, yet he has discovered a great and universal genius, which would have enabled him to succeed in some degree in whatever he undertook, especially if he had begun earlier. Having been for some time afflicted with an imposthume, which was deemed incurable, he grew weary of life, to which, says Pliny, he put an

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end with determined courage. There have been many editions of Silius Italicus. A correct one was published at Leipsic, in 1696, in 8vo., with notes by Cellarius: but the best is that cum notis integris variorum et Arnoldi Drakenborch. Traject. ad Rhen. 1717, in 4to. SILK, n. s. SILK'EN, adj.

Sax. reolc; Goth. silk; Dan. silke. The produce of the bombyx, see below: the derivatives following the root and silken being often used for soft; tender.

SILK WEAVER, n. s. SILK WORM.

Full many a lady fair, in court full oft Beholding them, him secretly envide,

And wished that two such fans, so silken soft, And golden fair, her love would her provide. Spenser. He caused the shore to be covered with Persian silk for him to tread upon.

Knolles.

The worms were hallowed that did breed the silk; And it was dyed in mummy, which the skilful Conserved of maidens' hearts. Shakspeare. Othello. Let not the creaking of shoes, or rustling of silks, betray thy poor heart to woman. Shakspeare.

Men counsel and give comfort to that grief
Which they themselves not feel; but, tasting it,
Their counsel turns to passion, which before
Would give perceptial medicine to rage,
Fetter strong madness in a silken thread,
Charm ach with air, and agony with words.

Id.

All the youth of England are on fire, And silken dalliance in the wardrobe lies. Id. Henry V.

Shall a beardless boy, A cockered, silken wanton, brave our fields, And flesh his spirit in a warlike soil, Mocking the air with colours idly spread, And find no check? Id. King John. These kinds of knaves, in plainness, Harbour more craft, and more corrupter ends, Than twenty silky ducking observants

That stretch their duties nicely. Id. King Lear. Grasshoppers eat up the green of whole countries, and silk-worms devour leaves swiftly.

Bacon's Natural History. She weeps, and words addressed seem tears dissolved,

Wetting the borders of her silken veil. Milton. Without the worm, in Persian silks we shine. Waller.

Broad were the banners, and of snowy hue, A purer web the silk-worm never drew.

Dryden.

The Chinese are ingenious silkweavers. Watts. Dress up virtue in all the beauties of oratory, and you will find the wild passions of men too violent to be restrained by such mild and silken language.

Id. on the Mind.

SILK. The culture of this important article of manufacture has hitherto been considered as the exclusive property of other climes, although we have the most positive evidence that the worms when reared in this country produce a material as well calculated for the manufacturers' use as those of France and Italy. As this is a subject that has lately occupied the attention of the Society for the promotion of Arts and Manufactures, who have printed a series of valuable practical observations from the pen of Mr. Stephenson, we cannot do better than commence our article by an analysis of their contents.

It appears that Mr. Stephenson was for several years a resident in the provinces of Languedoc and Quercy, where the utmost attention

is paid to the manufacture of silk. He begins by giving some account of the mulberry tree. He observes that there are two kinds of the black mulberry tree which have been cultivated in France. The first of these bears a fruit well known, and frequently presented at table, being the same which is cultivated in our gardens in the neighbourhood of London. But the leaves of this tree have been found, from experience, to be too harsh and too succulent, to prove in every respect a proper food for the silk-worm; and the silk it yields turns out to be coarse, and of an inferior quality. The second kind of the black mulberry tree carries a fruit inferior to the other in point of size, and improper for the table; but the leaf of it has been found to be superior to the first, as food for the silk-worm; and it is less harsh, less succulent, and yields silk of a finer quality than the one first mentioned. This second sort of the black mulberry is, in all probability, the particular kind which is said to be at present cultivated in the kingdom of Valencia, in Spain, for the use of their silkworms and, indeed, many of their old plantations in France consist of this sort. But thei new plantations consist wholly of the white mulberry tree, hereafter to be mentioned, which is the only one they now cultivate in all their nursery grounds, for the use of their silk-worms. There is a third sort, known by the name of the white mulberry, the leaf of which is more tender and less succulent than either of the other two, and has been found to produce silk of the finest and best quality.

Some people have been led to think that this kind of the mulberry tree does not carry any fruit, and that it can only be propagated by layers; but in this particular the fact stands much the other way. For, though the white mulberry may not perhaps produce any fruit in a climate so far to the north as ours, yet the truth is, that in climates such as that of the south of France, this tree carries fruit in very great quantities, though it is of a smaller kind than either of the two already mentioned. It is of a dusky white color, rather inclining a little to the yellow; and contains a number of small seeds, like mustard seed; from which large nurseries of this valuable tree are now annually raised all over the southern parts of France.

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For a number of years after the culture of silk was introduced into France, the people were accustomed to employ the leaves of all the different kinds of mulberry trees before mentioned, promiscuously and some grafts of the white mulberry from Piedmont, and from Spain, which carried a larger leaf than the one they had got in France, having been obtained from these countries, these grafts were put upon French seedling stocks, which had the effect of increasing greatly the size of the leaves, and was regarded as an acquisition, as it certainly produced a larger stock of leaves as food for the worms. The consequence of which was that this practice of grafting prevailed for a great many years all over Provence and Languedoc. But Monsieur Marteloy, a physician at Montpelier, who had made the culture of the silk-worm his particular study for a number of years together, at

last made it clearly apparent to the conviction of every body, by a regular course of attentive and well conducted experiments, that the leaf of the seedling white mulberry was the food of all others the best for this valuable insect; as the worms which were fed with this particular leaf were found to be more healthy and vigorous, and less subject to diseases of any kind, than those that were fed upon any of the other kinds of leaves above mentioned; and that their silk turned out to be of the very best quality. Since that time, namely, 1765, a decided preference has been given to this particular leaf beyond all the others.

As our British gardeners are more intelligent in their business than any of the French gardeners, it may, by some, perhaps be reckoned unnecessary to say any thing here, with respect to the culture of the mulberry tree: but when it is considered that the culture of this tree has been so anxiously attended to in France, for a long period of years past, and they succeed perfectly in this culture, it may not be deemed altogether improper to add here the method used in France in cultivating the mulberry tree.

Mr. Stephenson goes on to observe that their first object is to make choice of a spot of ground for their seed bed, of a gravelly or sandy soil, which has been in garden culture, or under tillage for some time, and which they know to be in good heart. When this ground is thoroughly dressed, they make drills at the distance of two feet from each other, in which they sow the seeds, in the same manner as they usually do lettuce for salads. They then cover the seeds lightly with some of the finest earth, after putting it through a sieve; and, if the weather happens to be dry, they water it slightly once or twice a week, as they judge to be necessary. These seeds they sow as above, at any time from the end of April to the end of May, and even during the first week in June; and some gardeners, the better to ensure success, were in the practice of sowing the seeds at three different times during the same season: to wit, the first sowing in the last week of April; the second about the middle of May; and the third in the beginning of June. When the plants are fairly above ground, they take particular care to keep them clear from weeds, and, from time to time, to point with a spade or a hoe the ground in the intervals betwixt the different drills.

After remaining for two years in the seed bed, they take up the plants: such of them as are of the size of a writing quill, they plant out in the nursery grounds; each plant at two feet distance from each other in the row, and the rows at three feet distance from each other, that there may be room for cleaning and dressing the ground betwixt the plants. At transplanting, they cut off nearly half the root, and also cut off the tops at about six or seven inches above the ground. All the other plants, which are too small for the nursery, they plant out thick by themselves, to remain for another year, or two, if necessary: after which they plant them out in the nursery grounds as above. The most proper time for transplanting the mulberry tree is just after the fall of the leaf in autumn.

When the plants in the nursery are sprung, they take care to strip off the side buds, and leave none but such as are necessary to form the head of the tree. If the plants in the nursery do not shoot well the first year, in the month of March following they cut them over about seven inches from the ground, which makes them come on briskly the year following. When the plants are grown to the size of one inch diameter, they plant them out in the fields where they are to remain, making the pits where they plant them of the size of six feet square, and dressing the ground for twenty inches, or two feet deep.

During the first year of planting out, they leave the whole buds which the trees have pushed out on the top until the following spring, when they take care to leave none but three or four branches to form the head of the tree; and, as the buds come out, they take off all those which appear upon the body of the tree, from the bottom all the way up to those which are left to form the head of the tree; and for several years after, at the seasons above mentioned, they take care to open the heads of the trees, when too thick of wood, and particularly to cut off any branch which seems to take the lead from the rest, and to engross more of the sap than what falls to its share, that the different branches may increase equally as much as possible. After the trees are planted out, and likewise while the plants are in the nursery grounds, they take care to dress the ground about the trees regularly three or four times a year, which greatly assists the trees to get on.

Here it is proper to mention that it is the practice in France to plant out some of their young plants from the nursery by way of espalier, in some sheltered situation, in a garden, for example, where the soil is not over rich: and, if it can be had, where the soil has a great proportion of gravel or sand; the intention of which is, to procure early leaves for the worms in their infant state; as these leaves generally come out more early upon dwarfish plants in a sheltered situation, than upon the trees planted out in a more open exposure; and upon this occasion they have also recourse for tender leaves to their young plants in the seed bed and nursery grounds.

Any quantity of the seed of the white mulberry can be obtained either from Montpelier or Marseilles, where it is regularly to be found for sale in the seed shops. It may also be obtained by the same means from Spain; the seed from which country is even preferable to that from France, as the Spanish tree carries a larger leaf than that of France, and has the leaf equally tender and good as the other, when used from the seedling trees.

From the experiments carried on by M. Marteloy, that gentleman made it fully appear that the leaves of the trees which grew in a rich soil were by no means proper food for the silkworm, as they were too luxuriant and full of juice for them; and that the leaves of those trees which were raised in a gravelly or sandy soil, where no manure was employed, were greatly to be preferred.

From these experiments, also, one of the rea

sons, and apparently the principal one, may now be pretty clearly pointed out, which rendered abortive the trials made in England, during the reigns of James I. and Charles II., for introducing the culture of silk into Great Britain; though that reason was altogether unknown in England, at the times these different trials were made. It appears to have been only this, that they had on other food to give to their worms but the leaves of the black mulberry, carrying the large fruit usually presented at our tables, which is now altogether rejected in France as an improper food for the worms; and which was rendered infinitely more destructive for these insects by the trees which produced them having been all of them reared in the richest grounds in England, namely, in the garden grounds about London, which we know are in a manner yearly loaded with dung.

The mulberry trees ought not to be pruned the first year after planting out, for fear of making them bleed too much; but in the second spring it is reckoned advisable to dress their heads, and to continue to repeat that dressing yearly, during the next ten or twelve years; taking care to make them hollow in the middle, so as to give a free passage for the air, and to render it easy to gather the leaves. After the first twelve years are over, it will be sufficient if a dressing of the same kind is regularly given to them once every three years. But as some of the branches may probably be broken annually, in gathering the leaves, care must be taken to prune all such branches as may happen to be thus broken, to prevent the trees from suffering materially by such accidents. In planting out the mulberry tree, in the field where it is to remain, care must be taken to cover the roots properly, so that the earth may not lie hollow upon them, which would injure the plant. They should also take care to prop the different trees with stakes, to prevent them from wind-waving; placing straw next the body of the tree, to prevent the bark from being hurt; and it will be proper also to surround them with briars or brambles, to preserve them from all injury from cattle.

Here it is proper to remark that the second crop of leaves which come out upon the mulberry trees, after having been stripped of their first leaves for the use of the s.lk-worm, are not allowed to fall off themselves in the autumn. They are gathered for the second time with care, a little before the time they would fall naturally, and are given for food to their sheep, and eaten by them with greediness, and by that means turn out to good account to the farmer. Before the culture of silk was introduced into that part of Languedoc which is near to the mountains of Cevennes, the peasantry over all that neighbourhood were miserably poor, as their soil, which is mostly gravel and sand, was incapable of carrying crops of any kind of grain whatever. But as it was found, upon trial, to answer remarkably well for the mulberry tree, the people entered with great alacrity into the culture of silk; and they have succeeded so well in that lucrative branch, that, from having been amongst the poorest, they are now more at their ease than most of the peasantry of that kingdom.

As an encouragement to the small heritors and farmers to plant mulberry trees upon their grounds, the French government are at an annual expense in keeping up large nurseries of these trees in many different parts of the country, whence the small heritors and farmers are liberally supplied gratis with whatever numbers of these trees they desire to plant out upon their grounds; and proper directions are ordered to be given along with the trees, by the gardeners who are charged with the care of these public nurseries, that the people to whom the trees are thus given may know how to treat them properly. This beneficent public measure is attended with great advantage to the country, as the poorer people are by this means saved from the trouble and expense of rearing the trees, until they come to be of a proper size for planting out in the fields, where they are intended to remain.

When the young mulberry trees are in the seed bed, and even when afterwards planted out in nursery grounds, and likewise for several years after they are planted out in the fields to remain, you must be careful every night, in the spring and 'summer seasons, to examine with care, all round your plants, for a little snail without a shell, which is very fond of the bark of these trees when young, and preys upon them prodigiously. These snails will cut over your young plants in the seed beds and nursery grounds, and will even continue to prey upon the trees till they are pretty old; and, though they do not absolutely kill the trees when planted out, yet they hurt them greatly, and retard their growth. These snails, therefore, must be gathered up every night as above mentioned, a little after sun-set, which is better than in the morning, because the mischief they occasion is generally done in the night; and they must be burnt, or otherwise effectually destroyed; for if you do not kill them they will find their way again to the trees.

Mr. Stephenson then proceeds to give an account of the manner used in France for disengaging the seeds from the fruit of the mulberry, which requires a considerable degree of labor as well as attention. Having gathered the quantity of fruit you propose to set apart for seed, which must be thoroughly ripe before it is pulled, you put the fruit into a large tub or vessel, where you cause a person to tramp and press it with his bare feet, in order to bruise the whole of it thoroughly, and by that means disengage the seed from the little pods or cells in which it is contained. You must at the same time have in readiness another tub, which must be pretty deep, into which you introduce a piece of flat wood, which must be made to rest upon the sides of the tub, at the distance of six, eight, or more inches from the bottom of the tub, as you shall judge to be necessary for your quantity of fruit. This cross piece of wood is calculated to support a round cane sieve, which is to rest upon it. This sieve must be very fine, that is, the holes must be very small and close set together, that as little of the pulp of the fruit as possible may go through the holes along with the seed.

Things being thus prepared, and the tub filled

30 far with water that it may rise more than half way up the brim of the sieve, when placed upon the piece of wood, you then put a handful or two of the bruised fruit into the sieve, which you rub hard with your hands upon the bottom of the sieve, in order to make the seed pass through the holes, and every now and then you lift up the sieve with both hands, and shake it to make the water pass through it, which carries the seed along with it. Besides rubbing the fruit with your hand upon the bottom of the sieve, as above, you also take it and rub it heartily betwixt the palms of your hands, rubbing the one hard against the other; as it takes a great deal of work and pains to get the seeds disengaged out of their little cells, and must be done effectually before the seeds will pass through the holes of the sieve. This work must be repeated till vou observe that the whole of the seed has passed through the holes of the sieve; after which you throw aside the pulp, and must proceed in the same manner with the rest of the fruit, till you have finished the whole. You then take the sieve and piece of wood out of the tub, and pour off all the water, when you will find the seed at the bottom; but along with it a great quantity of the pulp, which has been forced through the holes of the sieve, in rubbing the fruit hard upon the bottom of it with your hand, as above mentioned.

It should be noticed that all the seeds which swim upon the surface of the water are light and good for nothing, and must, therefore, be thrown aside. You then put the pulp and seed, which you find mixed together at the bottom of the tub, into another vessel, and fill the tub with water as at first, having put the piece of wood and the sieve in their proper places as before, after which you pass the pulp and seed, by degrees, through the sieve, by rubbing it with your hand upon the bottom as before, and lifting up the sieve from time to time, with both hands, and shaking it, as already mentioned. In passing it this second time you will disengage a great quantity of the pulp, which you throw aside from time to time, as soon as you observe that none of the seed remains amongst it. You then pour off the water as before; and, if you find that there is still some of the pulp remaining with the seed, you must pass it a third time through the sieve, which will effectually clean it, if your sieve is fine enough. If your sieve is too coarse, that is, if the holes are too large, it will occasion you a great deal more work, as you will be obliged to pass it oftener through the sieve, since that operation must be repeated till the seed is perfectly clean; after which you must spread the seed upon a clean cloth, and expose it to the sun, till it is thoroughly dry. Three days, or even four days, of a full sun are necessary to dry and harden the seed properly for keeping.

Upon this part of our subject it seems proper to add that in a cool moist country, such as about Paris or London, it is reckoned the mulberry tree carries a double, nay, nearly a triple quantity of leaves to what it can do in the hotter or drier climates, such as that of the south of France, which is judged to be owing to the moisture of the climate, and the superior rich

ness of the soil. In a cold moist climate a person is not able, even with the utmost care, to produce above the half of the cocoons from the same quantity of eggs which can be done in a warmer and drier climate. But, as in the colder climate the mulberry tree carries nearly three times the quantity of leaves, which it can do in the other, thence it arises that the colder climates, such as those before mentioned, are able, upon the whole, to raise at least as much silk, from the same quantity of eggs, as the warmer countries; because the quantity of food is the great article, as the grain or eggs of the silk-worm can easily be multiplied to as great a quantity as you please.

Having thus gone through the articles of greatest importance in relation to the first and leading branch of our subject, the next which naturally falls to be considered is the method observed in France in hatching the worms. But, before proceeding to this article, it may not be improper to premise the following particulars, as they seem justly to demand a very particular attention.

Here then it must be observed that the greatest care ought to be taken to procure healthy good seed or eggs, because it has been ascertained, from repeated experience, that the eggs from those houses where the worms were infected with bad' air carries along with it, to the worms produced therefrom, the same distempers to which the worms of the preceding year were subject. The eggs, in order to be properly preserved, should be kept in some dry place, with a free air not too hot; and you should avoid keeping them in any vault or cellar under ground, because any kind of damp is found to be destructive to them.

The eggs of the silk-worm have been found to degenerate in the space of five years; hence a change from time to time is judged to be necessary, taking care to have the eggs brought from a warmer to a colder climate. This, however, must be done by degrees, and not carried at once from one extreme to another. For example, eggs brought from the Levant, the Isle of Cyprus, or from other countries of the same latitude, ought not to be brought at once into such a cold climate as that of Flanders or the north of France; but should be first brought into such a climate as that of Provence or Languedoc, whence, after having remained there for two years, they can be brought with safety into the colder countries.

The first year that the eggs are brought from a warm to a cold climate, you must not expect great success from them: on the contrary, you will find, though the utmost care and attention are given to them, that the greatest part of the worms will die. But still you will be able to save enough to stock yourself sufficiently with eggs, which every succeeding year will be found to answer better as the worms become naturalised to the climate, which can only be brought about gradually; and indeed more time will be requisite for this purpose in Britain than in France, as the climate upon the continent is more fixed and steady than with us in England.

In transporting the eggs from one country to

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