784 SILK MANUFACTURE 



same manner, the sulphate of lime must, being in contact with the silicate of potash 

 or soda, form a silicate of lime ; and all these silicates strongly resist the action of 

 sea-water. As for sea-salt, which is a chloride of sodium, M. Kuhlmann proved that, 

 in the proportion in which it exists in sea-water, it will slowly decompose the silicate 

 of potash contained in the cement, and leave the silex free. The compositions pro- 

 posed have therefore the singular property, not only of resisting the action o^f 

 sea-water, but of actually becoming more insoluble the longer they are in contact 

 with it. A cement composed of 30 parts of rich lime, 50 of sand, 15 of un- 

 calcined clay, and 5 of powdered silicate of potash, is recommended by M. Kuhlmann 

 as having all the requisite hydraulic properties, especially for cisterns intended for 

 spring-water. In marine constructions care should be taken to add an excess of 

 silicate to those portions of cement which are exposed to the immediate contact of 

 the sea. See HYDRAULIC CEMENTS. 



Kansome's artificial stone is prepared by cementing sand with soluble silica, 

 or silicate of potash, and decomposing this salt with muriate of lime. See STONE, 

 ARTIFICIAL. 



SILICON, or SIXiXCXtrM. The base of silica or flint. It was first obtained by 

 Berzelius in 1823. Silicon is obtained by heating the double fluoride of potassium 

 and silicon with sufficient potassium to combine -with the whole of the fluorine, and 

 afterwards washing the mass with cold water, until no alkaline reaction is observable, 

 then boiling with water to decompose any of the double fluoride which may not have 

 been acted upon, and finally washing the silicon perfectly with hot water. 



Silicon is a dark-brown powder, heavier than water, infusible before the blowpipe, 

 non-volatile, increasing in density when considerably heated. Silicon exists in three 

 distinct forms : amorphous, graphitoi'dal, and diamond-like. Silicon, boron, and 

 carbon, indeed, exhibit great similarity. 



SXXiK MANUFACTURE. (Fabrique de soie, Fr. ; Seidenfabrik, Gor.) This 

 may be divided into two branches : 1. the production of raw silk ; 2. its filature and 

 preparation in the mill, for the purposes of the weaver. The threads, as spun by the 

 silkworm, and wound up in its cocoon, are all twins, in consequence of the twin 

 orifice in the lip of the insect through which they are projected. These two 

 threads are laid parallel to each other, and are glued more or less evenly together by 

 a kind of glossy varnish, which also envelopes them, constituting nearly 25 per cent, 

 of their weight. Each ultimate filament measures about 5^5 of an inch in average 

 fine silk, and the pair measures of course fully -j^ of an inch. In the raw silk, as 

 imported from Italy, France, China, &c., several of these twin filaments are slightly 

 twisted and agglutinated to form one thread, called single. 



The specific gravity of silk is 1'300, water being I'OOO. It is by far the most tena- 

 cious or the strongest of all textile fibres, a thread of it of a certain diameter being 

 nearly three times stronger than a thread of flax, and twice stronger than hemp. 

 Some varieties of silk are perfectly white, but the general colour is a golden yellow. 



The production of silk was unknown in Europe till the sixth century, when two 

 monks, who brought some eggs of the silkworm from China or India to Constanti- 

 nople, were encouraged to breed the insect, and cultivate its cocoons, by the Emperor 

 Justinian. Several silk manufactures were in consequence established in Athens, 

 Thebes, and Corinth, not only for rearing the worm upon mulberry-leaves, but for 

 unwinding its cocoons, for twisting their filaments into stronger threads, and weaving 

 these into robes. The Venetians having then and long afterwards intimate commer- 

 cial relations with the Greek Empire, supplied the whole of western Europe with silk 

 goods, and derived great riches from the trade. 



About 1130, Roger II., king of Sicily, set up a silk manufacture at Palermo, and 

 another in Calabria, conducted by artisans whom he had seized and carried off as 

 prisoners of war in his expedition to the Holy Land. From these countries, the silk 

 industry soon spread throughout Italy. It seems to have been introduced into Spain 

 at a very early period, by the Moors, particularly in Murcia, Cordova, and Granada. 

 The last town, indeed, possessed a flourishing silk trade when it was taken by Fer- 

 dinand in the 15th century. The French having been supplied with workmen from 

 Milan, commenced, in 1521, the silk manufacture; but it was not till 1564 that they 

 began successfully to produce the silk itself, when Traucat, a working gardener at 

 Nismes, formed the first nursery of white mulberry-trees, and with such success, that 

 in a few years ho was enabled to propagate them over many of the southern provinces 

 of France. Prior to this time, some French noblemen on their return from the con- 

 quest of Naples, had introduced a few silkworms with the mulberry into Dauphiny ; 

 but the business had not prospered in their hands. The mulberry-plantations were 

 greatly encouraged by Henry IV. ; and since then they have been the source of most 

 beneficial employment to the French people. James I. was most solicitous to intro- 

 duce the breeding of silkworms into England, and in a speech from the throne ho 



