SILK. 167 



It has been stated by P. Bolley that the glands of the silkworm 

 contain semi-liquid fibroin alone, and that on exposure to the air the 

 surface is acted upon by oxygen, transforming the external pellicle 

 into the more soluble form of sericin. Silk will readily imbibe 

 water; the fibre being so hygroscopic as sometimes to take up 30 

 per cent, of moisture. 



Silk fibres may be distinguished from others by curling up when 

 exposed to a flame, and by giving off the characteristic odour of 

 burning nitrogenous matter. A solvent for silk is a concentrated 

 solution of zinc chloride, 138 Tw. (sp. gr. 1'69), made neutral, or 

 boiled with excess of zinc oxide. The silk dissolves slowly if the 

 solution is cold, but rapidly if heated, forming a thickened gummy liquid. 



Silk Industry. The merits of the silk industry are referred to by 

 Sir Thomas .Wardle as follows: "We are in our sericultural wealth, 

 through having India, more than equal to France, Italy, or any other 

 country in the world, being in some respects better off than China, for 

 we are not confined to one species of silk, nor to two. India can 

 boast of the greatest silk-producing fauna in the world. She has 

 her varieties of Bombycidse, which feed on the mulberry leaf, both 

 wild and domesticated; she has her jungle broods of worms of many 

 sorts, more or less useful or to become useful by and by ; her Tussur 

 silk is now an established and well-rooted industry, a few years ago 

 in export non-existing; her Assamese women are clad in silks of the 

 Eri and Muga worms, of which as yet we know practically nothing, 

 and silken stuffs are handed down from matron to spinster but little 

 the worse for the wear of a generation." 



Topography and Remarks. The production of silk is carried on as 

 an industry to a large extent in Italy, Turkey, and Greece, also in France, 

 Spain, Japan, and Portugal. In all the countries mentioned it is culti- 

 vated and 'spun into yarns, or woven into the most elaborately figured and 

 lustrous of fabrics. In many countries the cultivation of silk is not only 

 carried on by private firms, but subsidies are also granted by the govern- 

 ment to encourage it. 



Silk Fibre Texture. In a report of the silk section at the 

 Manchester Exhibition, Sir Thomas Wardle gives particulars of a mul- 

 berry-fed silkworm cocoon (Bombyx mori), raised by G. Thome, Castle 

 Hill, Paramatta District, New South Wales. Description of the 

 cocoon and its silk fibres : Form, elliptical oblong, with slight medial 

 depression. Colour, light buff outside but yellow inside. Texture rather 

 loose, the silky walls of the cocoon being composed of successive layers. 

 The reelable cocoon thread or bave is composed of two cylindrical fibres 

 or brins, consisting of homogeneous matter (fibroin, Schorlemmer) sur- 



