THE TECHNOLOGIST. [Nov. 1, 1864. 



164 ON CHEMISTRY APPLIED TO THE ARTS. 



silk was worth its weight in gold. The most interesting fact for us is 

 the date of the introduction of the silkworm into Europe ; it is related 

 that in a.d. 555 two monks, returning from the East, concealed some 

 silkworms' eggs in their staves, and having succeeded in rearing the 

 worms, their culture soon spread through Greece and Turkey, and 

 gradually found its way into Italy towards the twelfth century. The 

 silk in use at the present day is chiefly derived from the Bombyx mori, 

 but the extensive disease which has, during the last eight or ten years, 

 destroyed very large numbers of the worms, has given rise to great 

 efforts to introduce some new species, two of which, the Bombyx mylitta, 

 feeding on the Palma christi or castor-oil tree, and the Bombyx ailanihus, 

 feeding on the plant from which it is named, have been to some extent 

 successful. The material forming the silk is secreted in two glands 

 placed on the side of the animal's body, whence it passes into an organ 

 called the spinaret, on each side of which are two other glands, which 

 secrete a gummy substance, and this uniting with the former forms the 

 silk fibre. Permit me to add here a fact which I think will interest you, 

 viz., the extraordinary quantity of silk which a small weight of eggs will 

 yield. Thus, four ounces of eggs will yield 87,900 to 117,000 cocoons, 

 and as on an average a pound of silk requires 270 cocoons, the four 

 ounces of eggs will give 422 lbs. of silk, or 100 lbs. of cocoons yield 

 generally 8 lbs. or about 14 per cent, of silk. The production of silk 

 fibre from cocoons is extremely simple. It is effected by placing the 

 cocoons in boiling water ; this softens or dissolves the gummy matter 

 which binds the fibres together, and the end of the fibre being detached 

 and placed on a reel, is easily wound. This is the state in which it is 

 usually imported into this country under the name of raw silk. When 

 two or more of these fibres are slightly twisted together they form what 

 is called tram or weft, and when two of the threads are twisted in 

 opposite directions and laid together they form organzine or warp. To 

 render this substance susceptible of dyeing, it is necessary to remove 

 the gum by an operation called boiling off, which consists simply in 

 boiling the silk for some time in a soap lye, and washing and wringing 

 it well afterwards, in which operation it loses about 21 per cent. The 

 following figures will show the chemical composition of silk : — 



Gelatine .... 19-08} 



Albumen . . . . 25 -47 I Commercial yield, 79 per 



Wax and fatty substances . 1*45 ( cent, of silk. 



Silk fibre .... 54-00) 



100-00 



FlBROINE. 



Carbon, 48*53 ; hydrogen, 6-50; nitrogen, 17-35; oxygen and sulphur, 

 27-62. 



Conditioning Silk. — This expression implies the ascertaining of the 

 real commercial value of silk, or, in other words, its condition ; and the 



