SILLI SILVER. 



261 



great many of these pairs of boards are placed 

 firmly in an oblong frame. Over this frame, there 

 is an endless web moving, which passes round rol- 

 lers at each end. This web carries upon it a series 

 of heckles, all moving with it. When these heckles 

 pass along the under side, their teeth act upon the 

 silk in the frame below, and clear it. When the 

 heckling is finished in a coarse machine, the boards 

 with the silk are placed in a finer heckle frame, 

 and the process is thus continued as far as is found 

 necessary. 



The silk thus heckled is now carried to a cutting 

 machine, where it is laid regularly upon an endless 

 web moving at a certain rate along the side of the 

 cutting machine. At the end, there are a series of 

 revolving knives, which cut the silken fibres into 

 lengths of an inch or more. 



In this state it is opened up, by being passed 

 through a blowing engine, similar to that described 

 in our article Cotton Manufacture. After being 

 blown, it is boiled in a lea of soap water for several 

 hours, in order to free it of the gum. 



After drying it passes through a carding machine, 

 like that represented in our plates of linen manufac- 

 ture. Like that machine, it is chiefly distinguished 

 from the cotton carding engine, by having several 

 doffers revolving on the surface of the large cylin- 

 der. After the carding, the drawing and roving 

 processes are performed by machinery exactly the 

 same as that used for cotton. 



The preparation being made, the spinning is ef- 

 fected by the organ jenny, or rather mule, a minute 

 account of which has been already given under the 

 article cotton. The singles are thus prepared. 



The doubling is effected by the common throstle. 



SILLI; Greek poems written in hexameters, 

 belonging to the class of satire, in which the phi- 

 losophers, and their doctrines in particular, were 

 ridiculed. The silli were often parodies on other 

 poems. Tymon and Didymus are famous writers of 

 silli. 



SILO; a Spanish word, signifying an excavation 

 about fourteen feet deep, for preserving grain. It 

 is best made in marly ground, not too dry. Over 

 the bottom a vaulted dome is built, rising eight and 

 a half feet, and surrounding the tube through which 

 the corn is poured in. The walls of the excavation 

 are lined with straw. Three hundred bushels of 

 wheat, preserved some time in a silo, were found, on 

 careful examination, to have increased in measure 

 one bushel, while the weight of the whole was di- 

 minished two and a half per cent. The expense of 

 preserving grain in granaries is generally estimated 

 at ten per cent. : in the larger silos, however, it is 

 only one per cent., if the grain is left shut up for two 

 years. On the farm of M. Ternaux, at St Ouen, 

 near Paris, it was found that the grain put in his 

 silos, in 1819, was sound and fresh in 1824. In. 

 Hungary, the same method of preserving grain is 

 common. 



SILO A, OR SILO AM; a fountain on the east 

 side of Jerusalem, between the city and the brook 

 Kedron, or Cedron. St John speaks of the pool of 

 Siloam (John ix. 7). The tower of Siloam, men- 

 tioned in Luke xiii. 4, is thought to have been 

 near this fountain. 



SILONG; a city of China, of the second rank 

 in Quangsi. 



SILVANUS ; an Italian rural deity, usually re- 

 presented with a sickle in his right hand and a 

 bough in his left, and sometimes with the horns and 

 feet of a goat. He is described as the protector of 



herds and trees from wolves and lightning, the 

 god of agriculture, or the defender of boundaries; 

 and offerings of various kinds were made to him. 

 He is often confounded with the Fauns, Pans and 

 Satyrs. See the articles. 



SILVER ; a metal which appears to have been 

 known almost as early as gold, and, without doubt, 

 for the same reason, because it occurs very fre- 

 quently in a state of purity in the earth, and re- 

 quires but an ordinary heat for its fusion. Men- 

 tion is made of silver in the book of Job, which is 

 considered the oldest of the books contained in the 

 Old Testament. The ores of silver are somewhat 

 numerous ; and we shall defer our account of them 

 to the conclusion of the present article, commenc- 

 ing with the chemical history of this metal. Pure 

 silver is of a fine white colour, with a shade of 

 yellow, without either taste or smell, and, in bril- 

 liancy, is inferior to none of the metallic bodies, if 

 we except polished steel. It is softer than copper, 

 but harder than gold. When melted, its specific 

 gravity is 10-47; when hammered, 10'510. It is 

 next in malleability to gold, having been beaten out 

 into leaves only 16( j 6C(0 th of an inch in thickness. 

 Its ductility is no less remarkable. It may be 

 drawn out into a wire much finer than a human 

 hair; so fine, indeed, that a single grain of silver 

 may be extended about 400 feet in length. Its 

 tenacity is such, that a wire of silver 0-078 of an 

 inch in diameter is capable of supporting a weight 

 of 187*13 pounds avoirdupois without breaking. 

 Silver melts when heated completely red-hot; and, 

 while in the melted state, its brilliancy is greatly 

 augmented. If the heat be increased after the silver 

 is melted, the liquid metal boils, and may be vola- 

 tilized ; but a very strong and long continued heat is 

 necessary. Gasto Claveas kept an ounce of silver 

 melted in a glass-house furnace for two months, and 

 found, by weighing it, that it had sustained a loss oi 

 one twelfth of its weight. When heated upon char- 

 coal under the flame of the compound blow-pipe, 

 however, the silver is volatilized with rapidity, pass- 

 ing off in a visible smoke. When cooled slowly, 

 its surface exhibits the appearance of crystals; and, 

 if the liquid part of the metal be poured out as soon 

 as the surface congeals, pretty large crystals of 

 silver may be obtained. ^Silver is not oxidized by 

 exposure to the air 5 it gradually, indeed', loses its 

 lustre, and becomes tarnished; but this is owing to 

 a different cause. Neither is it altered by being 

 kept under water. But, if it be kept for a long 

 time, melted in an open vessel, it gradually attracts 

 oxygen from the atmosphere, and is converted into 

 an oxide. When silver is dissolved in nitric acid, 

 and an alkali dropped into the solution, a brown- 

 coloured precipitate falls in flocks, which, when 

 washed and dried, constitutes the oxide of silver. 

 Its colour becomes a dark brown when dried. Its 

 specific gravity is 7' 14. When exposed to the di- 

 rect rays of the sun, it gives out oxygen gas, and is 

 converted into a black powder, the nature of which 

 has not been examined. The oxide of silver is a 

 compound of 93-1 silver and 6-8 oxygen. When 

 oxide of silver is dissolved in ammonia, and the 

 solution left exposed to the air, it is soon covered 

 with a brilliant pellicle, which is a suboxide of sil- 

 ver. A superoxide of silver appears to be formed, 

 when a plantina wire from the positive extremity 

 of a galvanic battery is plunged into a weak solu- 

 tion of nitrate of silver, the compound in question 

 accumulating in iron-black octahedrons upon the 

 wire. Silver does not burn in chlorine gas, even 



