SIL 
count of its superior wholesomeness, com< 
pared with copper, brass, or lead, for culi- 
nary purposes, it resisting the corroding 
power of vinegar and other weak acids. The 
metals that are usually covered with silver, 
are copper and brass, and sometimes iron, 
and there are three distinct modes of per- 
forming the operation. 1 . Silvering by amal- 
gamation, is thus performed : to a solution 
of nitrated silver add some plates of copper, 
which will throw down the silver in its me- 
tallic state, and very finely divided ; scrape 
it from the surface of the copper, wash it 
well and diy it. Of this powder take half 
an ounce, of common salt and sal ammo- 
niac two ounces, and of corrosive sublimate 
one drachm, rub them well together, and 
make them into a paste with a little water. 
Then take the vessel to be silvered, and 
clean it by means of a little very dilute 
aquafortis, or by scouring it with a mixture 
of common salt and tartar. When it is per- 
fectly clean, rub it with the above-mention- 
ed paste till it is entirely covered with a 
white metallic coating; this coating is an 
amalgam produced by the decomposition of 
the corrosive sublimate, by means of the 
copper, to the surface of which it applies 
very closely and expeditiously. The cop- 
per being thus silvered over, is to be wash- 
ed, dried, and afterwards heated nearly red, 
in order to drive oif the mercury ; the sil- 
ver remains behind, adhering firmly to the 
copper, and capable of being highly polish- 
ed. 2. Silvering by luna cornea. Prepare 
the luna cornea in the usual manner, by 
pouring a solution of common salt into ni- 
trate of silver, as long as any precipitation 
takes place, and boiling the mixture ; the 
white curdy matter, thus obtained, is to be 
mixed with three parts of good pearl-ash, 
one part of washed whiting, and somewhat 
more than one part of common salt. The 
surface of the brass being cleared from 
scratches, is to be rubbed with a piece of 
old hat and rotten stone, to remove any 
grease, and then is to be moistened with 
salt and water ; a little of the composition 
being now rubbed on with the finger, the 
surface of the metal will presently be co- 
vered with silver. Then wash it well, rub 
it dry with soft rag, and, as the coat of sil- 
ver is extremely thin, cover it with transpa- 
rent varnish, to preserve it from tarnish. 
This kind of silvering is very imperfect, 
and is only used for the faces of clocks, the 
scales of barometers, and similar objects. 
3. Silvering by silver in substance. There 
are three ways of performing this. The 
SIL 
first is, by mixing together twenty grains of 
silver, precipitated by copper, two drachms 
of tartar, two drachms of common salt, and 
half a drachm of alum; this composition 
being rubbed on a perfectly clean surface 
of copper or brass, will cover it with a thin 
coating of silver, which may afterwards be 
polished with a piece of soft leather. A 
still better way is that which is called 
French plating, which consists in burnish- 
ing down upon the surface of tlie copper 
successive layers of leaf-silver to any re- 
quired thickness. In this the silver has 
much more solidity than in any of the for- 
mer, but the process is tedious, and the 
junctures of the leaves of silver cannot al- 
ways be entirely concealed. The English 
method of plating (in those works to 
which it is applicable) appears to be the 
best of all. It is thus performed : one of 
the surfaces of an ingot of copper is render- 
ed quite smooth and clean, and is sprinkled 
over with glass of borax ; upon this is laid 
a plate of fine silver, about one-twelfth of 
the weight of the copper, and the two are 
carefully bound together by wire ; the mass 
is now exposed to a full red heat, which 
melts the borax, and causes the silver to ad- 
here to the copper ; the ingot is now passed 
through a rolling press, and formed into a 
plate ; both the silver and copper extend- 
ing uniformly during the whole process, at 
the conclusion of which, the two metals are 
inseparably fixed to each other. See Aikin’s 
“ Dictionary.” 
SILURUS, the silure, in natural history, 
a genus of fishes of the order Abdominales. 
Generic character : head large, naked, and 
depressed ; mouth extremely wide, and fur- 
nished with long feelers or tentacula ; eyes 
small, body lengthened, caked ; first ray of 
the pectoral or dorsal fin, serrated with re- 
versed spines. There are twenty-nine spe- 
cies, of which the following most deserve 
notice. 
S. glanis is generally about three feet 
long, though it has been seen of twelve, and 
of the weight of three hundred pounds, and 
consequently is one of the very largest of 
European river fishes. It is most plentiful 
in the north, is seldom seen in motion, and 
commonly lies ingulfed in mud at the bot- 
toms, with its mo\ith open, and its long ten- 
tacula moving about in every direction. 
These last being similar in appearance to 
worms, are mistaken for such by many 
fishes, which are, by this deception, drawn 
within the jaws of destruction. Its flesh is 
used for its cheapness, rather than its ex- 
