15 



SILK WORM AND SILK MANUFACTURE. 



and of a shining fracture, lis weight j 

 is nearly one third of the raw silk from 

 which it was extracted. It may he sepa- 

 rated from silk by soap as well as water, 

 and the soap leys containing it, soon pu- i 

 trefy. 



Besides the varnish, silk contains another 

 substance to which it owes its yellow col- 

 our, this substance possesses the proper- 

 ties of Resin. It is yellow, soluble in 

 Alcohol, and in a mixture of Alcohol and 

 Muriatic Acid. Beaume, has ascertained 

 that by this last mixture, it may be sepa- 

 rated completely, and the silk deprived 

 of it assumes a fine white colour. 



The chemical properties of silk itself, 

 have been but imperfectly examined. It 

 is not acted on by water or alcohol, has no 

 taste, and is but impertectly combustible; 

 though fire rapidly blackens and decom- 

 poses it. When distilled, it yields accord- 

 ing to Newman, an uncommonly great pro- 

 portion of ammonia. The fixed alkalies 

 dissolve it by the assistance of heat, and 

 it is not unlikely that they form with it, 

 an animal soap. It is dissolved likewise, 

 by sulphuric and muriatic acids, and by 

 nitric acid. 



By the action of this last acid, Barthol- 

 let obtained from silk some oxalic acid, 

 and a fatty matter which swam on the 

 surface of the solution. By a similar 

 treatment Welter obtained fine yellow 

 crystals, very combustible, to which he 

 gave the name of yellow bitter principle. 



Silk is very little susceptible of putre- 

 faction. Dr. Wilson, of Falkirk, says 

 that a ribbon was lately found in the 

 church yard of that town, wrapt round 

 the bone of the arm. It was uninjured, 

 though it had lain eight years in the earth. 

 We know at the same time, that when silk 

 is kept in a damp place it rots (to use the 

 common language,) in a much shorter 

 time. 



Maniif act lire, or Preparation of Silk. 

 When the silk worms have completed 

 their balls or cocoons, they are collected 

 and put into little baskets, and thus expos- 

 ed to the heat of an oven to kill the in- 

 sect, which without this precaution would 

 not fail to open itself to go away and use 

 those new wings abroad, it has acquired 

 within; ordinarily, they only wind the 

 more perfect balls; those that are double, 



or too weak or too coarse, are laid aside, 

 not altogether useless, but that, being im-- 

 pi'oper for winding they are reserved to 

 be drawn out into skeins. The balls are 

 of difierent colours; the most common are 

 yellow orange colour, Isabella, and flesh 

 colour; there are some also of a sea-green, 

 others of a sulphur colour, and others are 

 white; but there is no necessity of sepa- 

 rating the colours and shades apart, ta 

 wind them, as all the colours are to be lost 

 in the future scouring and preparing of the 

 silk. The goodness of silk is best distin- 

 guished by its lightness. The organzine 

 silk is the best of any made in the coun- 

 try of Piedmont, and two threads are equal 

 in fineness, that is, in smoothness, thick- 

 ness and length, for the thread of the first 

 twist. For the second it matters not whe- 

 ther the single thread be strong before the 

 two are joined, unless to see whether the 

 first twist proves well. It is necessary, 

 that the silk be clean; and it is to be ob- 

 served that the straw coloured is generally 

 the lightest, and the white the heaviest of 

 all; the skeins should be even, and all of 

 them of an equality, which shows that 

 they were wrought together; otherwise 

 we may with justice suspect that it is refuse 

 silk, and cannot be equally drawn out and 

 spun, for one thread will be shorter than 

 the other, which is labour and loss. 



It will also be requisite to search the 

 bale more than once and take from out of 

 the parcels a skein to make an essay; for, 

 unless it is known by trial, there is the 

 greatest danger of being cheated in this 

 commodity. To wind silk from off the 

 balls two machines are necessary; the one 

 a furnace with its copper, the other a reel 

 or frame, to draw the silk: the winder 

 then seated near the furnace, throws into 

 the copper of water over the furnace (first 

 heated and boiled to a certain degree, 

 which custom alone can teach) a handful 

 or two of balls, which have been first well 

 purged of all their loose furry substance. 

 The winder then stirs the whole very 

 briskly about with birchen rods, bound 

 and cut like branches; and when the heat 

 and agitation have detached the ends of 

 the silk of the cocoons, which are apt to 

 catch on the rods, the ends ol the silk are 

 to i)e drawn forth and joined ten or twelve, 

 or even fourteen of ihem together, and 

 lormed into threads according to the size 



