256 



S1L1U8 SILK. 



Silex, . 



I'rotoxiili* nt m:ui_- in . 

 Protoxide of iron. 



WllttT. 



Carbonic acid. 



1350 

 323 

 9923 



It is found in primitive districts, usually in connexion 

 \\ith beds of iron ore. Localities of it exist in the 

 llartz, in Sweden, and in Devonshire, England. 

 This species is sometimes wrought into articles of 

 ornament. When polished, its colour and lustre 

 are extremely delicate. 



SILIUS, CAIUS, surnamed Italicus, was born in 

 the reign of Tiberius, about the year fifteen. The 

 origin of his surname is uncertain. At Rome, he 

 applied himself to the bar, and became a celebrated 

 orator and advocate. He was consul at the time 

 of Nero's death, and incurred some reproach for 

 assisting in that tyrant's prosecutions, but acquired 

 honour from his conduct in the proconsulate of 

 Asia, assigned to him by Vespasian, from which he 

 retired into private life, and collected books, sta- 

 tues, and busts of eminent men. He finally retired 

 to his seat in Campania, where, being seized with 

 an incurable ulcer, he put an end to his life by star- 

 vation, in his seventy-fifth year. The only work 

 of Silius which has reached modern times, is an 

 epic poem on the second Punic war, in sixteen 

 books, written with more diligence than genius. It 

 contains, however, occasional splendid passages; and 

 his description of the passage of Hannibal across 

 the Alps is particularly admired. The best edi- 

 tions are those of Drakenborch (1717, 4to.), and 

 of Ruperti (Gottingen, 17958, 2 vols., 8vo.). 



SILK, a well known species of glossy thread, 

 spun by several species of the larvao or caterpillars 

 of the insects classed by Entomologists under the 

 genus Phalcena. Of these, the species Phalana Al- 

 tus produces the greatest quantity of thread, but 

 the species most commonly employed in Europe is 

 the Phalcena Bombyx. The silk worm, like all 

 others of its class, undergoes, during the course of 

 its existence, several transformations. The changes 

 of form it assumes are four. The eggs of the silk 

 worm are deposited during the summer, by the 

 female, at this period in the form of a grey moth. 

 The eggs, when first laid, are in size similar to a 

 grain of mustard seed and of a yellow colour, which 

 colour, in two or three days, changes to a bluish 

 cast. These eggs are covered with a liquid which 

 glues them to the cloth or paper on which the 

 female is made to deposit them, but from which 

 they are freed easily by immersion in cold water; 

 and being afterwards dried and kept at a proper 

 temperature, they may be preserved during the win- 

 ter and spring without danger, until the food on 

 which they feed, when in a more perfect state, is ripe 

 for consumption. The temperature at which the 

 eggs ought to be kept must not vary many degrees 

 from 55 Fahrenheit. The eggs are preserved by 

 being tied up in flat packages, containing about an 

 ounce each. For hatching in France they are tied 

 round the girdles of the women during the day, and 

 placed under their pillows at night. When other- 

 wise treated, they are placed in a room heated gradual- 

 ly by a stove up to a temperature of about 80. In 

 the course of eight or ten days the eggs are hatched. 

 The worms are now covered with sheets of paper 

 on which leaves of the mulberry tree have been 

 spread. The sheets of paper are perforated with 

 numerous small holes, through which the worms 

 make their way up to the mulberry leaves, their 



natural food. The leaves soon become covered 

 with worms. These leaves with the worms are 

 now carried off the sheets of paper, and laid upon 

 shelves of wicker work covered with brown paper. 

 This is repeated twice a day, until all the hatched 

 worms are laid on the wicker work. In a well ap- 

 pointed nursery, this ought to be completed in from 

 two to three days. Great care and attention is re- 

 quired on the part of the nurses to keep the room 

 at a proper temperature and well ventilated, and to 

 supply the worms at proper intervals with fresh 

 leaves, with as little trouble to the animal as pos- 

 sible, as the silk worm is remarkable for its indis- 

 position to move from its place; a circumstance 

 which greatly lessens the labour of the attendants. 



The silk worm, when first hatched, is black in 

 the colour, and in length does not exceed one 

 fourth of an inch. The desire for food is the first 

 symptom it exhibits of life, and at this period it is 

 more active than at any other. When about eight 

 days have elapsed after its hatching, its head be- 

 comes considerably enlarged, and it turns sick, 

 refuses food, and remains in a state of lethargy for 

 about three days. This sickness would appear to 

 arise from the pressure of the animal's skin, which 

 has become too tight for the increased bulk of its 

 body. Indeed the very great difference in the size 

 of the worm, from the beginning to the end of its 

 caterpillar state is so great, that nature has fur- 

 nished it with several skins, each of which it casts 

 in succession. The necessity of these wise ar- 

 rangements will be the more apparent to the reader, 

 when he is informed, that in the short space of one 

 month, the weight of the worm is increased several 

 thousand times. When the process of casting the 

 skin has been performed, the animal again revives 

 and betakes itself to food. It is extremely inter- 

 esting to watch the several steps in the process of 

 moulting. In order to diminish the action of the 

 skin to be cast, upon the new skin, the animal exudes 

 a lubricating humour between them, which renders 

 them more easy of separation. Small silken threads 

 are likewise emitted, which bind the skin to the 

 spot on which it now rests. These acts call forth 

 considerable exertions, and after they are per- 

 formed, the worm rests quiet for a little to recover 

 its energy. It now rubs its head among the leafy 

 fibres surrounding it, and breaks through the skin 

 of the head, then its front legs, and afterwards 

 the whole body. On examining the cast skin, it 

 will be found that the covering has been thrown off 

 the animal entirely, even to the jaws and teeth. 

 Sometimes the outer skin is not entirely detached, 

 in which cases the animal generally dies. In five 

 days after the first moulting, the worm has acquired 

 considerable size, being now generally about half an 

 inch long, at which period it again sickens, and a 

 second moulting takes place. In five days more, 

 it has acquired the length of three fourths of an 

 inch, and a third moulting comes on. In five days 

 more, the worm casts its fourth and last skin, hav- 

 ing increased in length to about two inches. It 

 now devours much food, and increases greatly in 

 magnitude for ten days, when it has reached its full 

 growth of about three inches in length. 



The worm may now be more advantageously 

 examined as to its structure than at any other 

 period. Its body is begirt by twelve rings, which ap- 

 proach to or recede from each other during the motion 

 of the animal. It is furnished with six scaly legs 

 on front, and ten membranous ones, called holders, 

 behind which latter are terminated by small hooks. 





