780 SILK MANUFACTURE 



with an abundance of food every six hours in succession. In shifting their bed, a 

 piece of network being laid over the wicker-plates, and covered with leaves, the 

 worms will creep up over them ; when they may be transferred in a body upon the 

 net. The litter, as well as the sickly worms, may thus be readily removed, without 

 handling a single healthy one. After the third age, they maybe fed with entire leaves ; 

 because they are now exceedingly voracious, and must not be subsequently stinted in 

 their diet. The exposure of chloride of lime, spread thin upon plates, to the air of the 

 magnaniere, has been found useful in counteracting the tendency which sometimes 

 appears of an epidemic disease among the silkworms, from the foetid exhalations of 

 the dead and dying, 



When they have ceased to eat, either in the fourth or fifth age, according to the 

 variety of the bombyx, and when they display the spinning instinct by crawling up 

 among the twigs of heath, &c., they are not long in beginning to construct their 

 cocoons, by throwing the thread in different directions, so as to form the floss, 

 JUoselle, or outer open network, which constitutes the bourre or silk for carding and 

 spinning. 



The cocoons destined for filature, must not be allowed to remain for many days 

 with the worms alive with them ; for should the chrysalis have leisure to grow 

 mature or come out, the filaments at one end would be cut through, and thus lose 

 almost all their value. It is therefore necessary to extinguish the life of the animal 

 by heat, which is done either by exposing the cocoons for a few days to sunshine, by 

 placing them in a hot oven, or in the steam of boiling water. A heat of 202 Fahr. is 

 sufficient for effecting this purpose, and it may be best administered by plunging tin 

 cases filled with the cocoons into water heated to that pitch. 



80 pounds French ( = 88 Engl.) of cocoons, are the average produce from one ounce 

 of eggs, or 100 from an ounce and a quarter; but M. Folzer of Alsace obtained 

 no less than 165 pounds. The silk obtained from a cocoon is from 750 to 1,150 feet 

 long. The varnish by which the coils are glued slightly together, is soluble in warm 

 water. 



The silk husbandry, as it may be called, is completed in France within six weeks 

 from the end of April, and thus affords the most rapid of agricultural returns, 

 requiring merely the advance of a little capital for the purchase of the leaf. In buying 

 up cocoons, and in the filature, indeed, capital may be often laid out to great advan- 

 tage. The most hazardous period in the process of breeding the worms, is at the third 

 and fourth moulting ; for upon the sixth day of the third age, and the seventh day 

 of the fourth, they in general eat nothing at all. On the first day of the fourth age, 

 the worms proceeding from one ounce of eggs will, according to Bonafons, consume 

 upon an average twenty-three pounds and a quarter of mulberry-leaves ; on the first 

 of the fifth age, they will consume forty-two pounds ; on the sixth day of the same 

 age, they acquire their maximum voracity, devouring no less than 223 pounds. From 

 this date their appetite continually decreases, till on the tenth day of this age they 

 consume only fifty-six pounds. The space which they occupy upon the wicker-tables, 

 being at their birth only nine .feet square, becomes eventually 239 feet. In general, 

 the more food they consume the more silk will they produce. 



A mulberry-tree is valued, in Provence, at from 6(2. to 10<. ; it is planted out of the 

 nursery at four years of age ; it is begun to be stripped in the fifth year, and affords 

 an increasing crop of leaves till the twentieth. It yields from 1 cwt. to 30 cwts. of 

 leaves, according to its magnitude and mode of cultivation. One ounce of silkworm 

 eggs is worth in France about 2 francs ; it requires for its due development into 

 cocoons about 15 cwts. of mulberry-leaves, which cost upon an average 3 francs per 

 cwt. in a favourable season. One ounce of eggs is calculated, as I have said, to pro- 

 duce from 80 to 100 pounds of cocoons, of the value of 1 fr. 25 centimes per pound, 

 or 125 francs in the whole. About 8 pounds of reeled raw silk, worth 18 francs a 

 pound, are obtained from these 100 pounds of cocoons. 



There are three denominations of raw silk : viz., organzine, frame (shute or tram), 

 and floss. Organzine serves for the warp of the best silk stuffs, and is considerably 

 twisted; tram is made usually from inferior silk, and is very slightly twisted, in order 

 that it may spread more, and cover better in the weft ; floss, or bourre, consists of the 

 shorter broken silk, which is carded and spun like cotton. Organzine and trame 

 may contain from 3 to 30 twin filaments of the worm ; the former possesses a double 

 twist, the component filaments being first twisted in one direction, and the compound 

 thread in the opposite ; the latter receives merely a slender single twist. Each twin 

 filament gradually diminishes in thickness and strength, from the surface of the 

 cocoon, whore the animal begins its work in a state of vigour, to the centre, where it 

 finishes it, in a state of debility and exhaustion ; because it can receive no food from 

 the moment of its beginning to spin by spouting forth its silky substance. The 

 winder is attentive to this progressive attenuation, and introduces the commencement 



