5 I L 
S I L 
S I* L 
action of this last acid, BerthoUet obtained 
from silk some oxalic acid, and a fatty matter 
which swam on the surface of the solution. 
By a similar treatment, Welter obtained line 
yellow crystals, very combustible, to which 
lie gave the name of yellow bitter principle. 
Silk is very little susceptible of putrefac- 
tion. Dr. Wilson, of Falkirk, says, that a 
ribbon was lately found in the churchyard of 
that town wrapt round the bone of the arm. 
It was uninjured, though it had lain eight 
years in the earth. We know, at the same 
time, that when silk is kept in a damp place it 
rots (to use the common language) in a much 
shorter time. 
Sii.k, manufacture, or preparation of. 
When the silkworms have completed their 
balls or cocoons (see Phaiwena, Vol. II. p. 
389), they are collected, and put into little 
baskets ; and thus exposed to the heat of an 
oven, to kill the insect, which, without this 
precaution, would not fail to open itself to go 
away and use those new wings abroad, it has 
acquired within. 
Ordinarily, they only wind the more per- 
fect balls ; those that are double, or too weak, 
or too coarse, are laid aside, not as altogether 
useless, but that, being improper for winding, 
they are reserved to be drawn out into skains. 
The balls are of different colours; the most 
common are yellow, orange-colour, isabella, 
and flesh-colour; there are some also of a 
sea-green, others of a sulphur-colour, and 
others white; but there is no necessity for 
separating the colours and shades to wind 
them apart, as all the colours are to be lost in 
the future scouring and preparing of the silk. 
The goodness of silk is best distinguished by 
Its lightness. The organzine silk is the best 
of any made in the country of Piedmont, and 
two threads are equal in fineness, that is, in 
smoothness, thickness, and length, for the 
thread of the first twist. For the second, it 
matters not whether the single thread is 
strong before the two are joined, unless to see 
■whether the first twist proves well. It is ne- 
cessary that he silk be clean ; and it is to be 
observed, that the straw-coloured is generally 
the lightest, and the white the heaviest of all". 
The skains should be even, and all of an equa- 
lity, which shews that they were wrought to- 
gether; otherwise we may with justice suspect 
that it is refuse silk, and cannot be equally 
drawn out and spun, for one thread wiil be 
shorter than the other, which is labour and 
loss. It will also be requisite to search the 
bale more than once, and take from out of 
the parcels a skain to make an essay; for un- 
less it is known by trial, there is the greatest 
danger of being cheated in this commodity. 
To wind silk from off the bails, two machines 
are necessary; the one a furnace, with its 
Copper ; the other a reel, or frame, to draw 
the silk. The winder then, seated near the 
furnace, throws into the copper of water over 
the furnace (first heated and boiled to a cer- 
tain degreej which custom alone can teach) a 
handful or two of balls, which have been first 
•well purged of all their loose furry substance. 
She then stirs the whole very briskly about 
with birchen rods, bound and cut like brushes; 
and when the heat and agitation have detach-- 
ed the ends of the silks of the cocoons, 
which are apt to catch on the rods, she draws 
them forth, and joining ten or twelve, or even 
fourteen of them together, she forms them into 
threads, according to the size required to 
the works they are destined for: eight 
ends sufficing for ribands ; and velvets, 
&c. requiring no less than fourteen. The 
ends, thus joined into two' or three threads, 
are nrst passed into the holes of three iron 
rods, in the fore-part of til?: reel, then upon 
the bobbins or pulleys, and at last are drawn 
out to the reef itself, and there fastened; 
each to an end of an ann or branch ol the 
reel. Thus disposed, the winder, giving mo- 
tion to the reel, by turning the handle, guides 
the threads; substitutes new ones, when any 
of them break, or any of the balls are wound 
out; strengthens them, where necessary, by 
adding others ; and takes away the balls wound 
out, or that, having been pierced, are full of 
water. 
In this manner, two persons will spin and 
reel three pounds of silk in a day, which is 
done with greater dispatch than is made by 
the spinning-wheel or distaff. Indeed, ali 
silks cannot be spun and reeled atter this 
manner; either because the balls have been 
perforated by the silkworms themselves, or 
because they are double, or too weak to bear 
the water; or because they are coarse, &c. 
Of all these together, they make a par- 
ticular kind of silk, called fioretta ; which be- 
ing carded, or even spun on the distaff, or the 
wheel, in the condition it comes from the ball, 
makes a tolerable silk. 
As to the balls, after opening them with 
scissars, and taking out the insects (which are 
of some use for the feeding of poultry), they 
are steeped three or four days in troughs, the 
water of which is changed every day to pre- 
vent their stinking. When they are well 
softened by this scouring, and cleared of that 
gummy matter the worm had lined the inside 
with, and which renders it impenetrable to the 
water, and even to air itself, they boil them 
half an hour in a lye of ashes, very clear and 
well strained: and after washing them out in 
the river, and drying them in the sun, they 
card and spin them on the wheel. &c. and 
thus make another kind of fioretta, somewhat 
inferior to the former. 
As to the spinning and reeling of raw silks 
off the balls, such as they are brought from 
Italy and the Levant, the first is chiefly per- 
formed on the spinning-wheel; and the latter, 
either on hand-reels, or on reels mounted on 
machines, which serve to reel several skains 
at the same time. 
As to the milling, they use a mill composed 
of several pieces, which may mill two or three 
hundred bobbins at once, and make them 
into as many skains. 
For the dyeing of silks, see Dyeing. 
S1LPHA, a genus of insects of the order 
coleoptera. The generic character is, an- 
tenna; thickening towards the tip; wing- 
sheaths margined; head prominent; thorax 
flattish, margined. The insects of the genus 
silpha, of which there are 35 species, are ge- 
nerally found among decaying animal or ve- 
getable substances, frequenting dung-hills, 
carrion, &c. and deposit their eggs chiefly in 
the latter. The larva; are of a lengthened 
shape, and of an unpleasant appearance, be- 
ing generally roughened with minute spines 
and protuberances. The most remarkable 
oi the European species, and which is by no 
means uncommon in our own country, is the 
silpha vespillo, distinguished by having the 
67g 
wing-sheaths considerably shorter than the 
abdomen, or as if cut off at the tips: they are 
also each marked by two waved, orange-co- 
loured, transverse bars, the rest of the iusect 
being black: the general length of the animal 
is about three quarters ot an inch. Ihis in- 
sect seeks out some decaying animal sub- 
stance in which it may deposit its eggs, and 
in order to their greater security, contrives to 
bury it under ground. Three or four insects, 
working in concert, have been known to drag 
under the surface the body ol so large an 
animal as a mole in the space of an hour, so 
that no trace of it has appeared above ground. 
The eggs deposited by the parent insects are 
white, and of an ova! or rather subcylindric 
shape: from these are hatched the larva;, 
which, when full-grown, are more than an 
inch in length, and of a yeilowish-white co- 
lour, with a scaly orange-coloured shield or 
bar across the middle ot each division ol the 
bodv. Each of these larvae forms for itsell an 
oval cell in the ground, in which it changes 
to a yellowish chrysalis, resembling that ot a 
beetle; out of which, in the space of about 
eighteen days, proceeds the perfect insect. 
This species possesses a considerable degree 
of elegance, but generally diffuses a very 
strong and unpleasant smell : it flies with 
considerable strength and rapidity, and is ge- 
nerally seen on the wing during the hottest 
part of the day. In many parts of North 
America is found a variety, differing merely 
in size, being far larger than the European 
kind, and measuring an inch and a half in 
length. 
SILPHIUM, a genus of plants belonging 
to the class of syngenesia, and to the order of 
polygamia necessaria; and in the natural sys- 
tem arranged under the 49th order, compo- 
sitie. The receptacle is paleaceous ; the pap- 
pus has a two-horned margin, and the calyx 
is squamose. There are eight species; the 
laciniatum, terebinthinum, perfoliatum, con- 
natum, asteriscum, trifoliatunqarboreum, and 
trilobatum. The first six of these are natives 
of North America. 
Several of the silphae are of an entirely 
oval outline: of this kind is the S. thoracica, 
which is easily distinguishable by its red tho- 
rax, every other part of the animal being 
coal-black : it is about half an inch in length. 
Silpha atrata is of similar size, but totally 
black, and has the wing-sheaths marked by 
three rising lines: its larva, which may be 
found in gardens, is of a lengthened shape and 
of a black colour. See Plate Nat. Hist., figs. 
361 anrl 362. 
SILVER, in natural history, is a metal of 
a fine white colour, without either taste or 
smell; and in point of brilliancy perhaps in- 
ferior to none of the metallic bodies, if we ex- 
cept polished steel. Its hardness is 7. When 
melted, its specific gravity is 10.47S ; when 
hammered, 10.60<>. " In malleability, it is in- 
ferior to none ot the metals, if we except, 
gold, and perhaps also platinum. It may be 
beaten out into leaves only 16Q Vff o inch 
thick. Its ductility is equally remarkable : it 
may be drawn out into wire much finer than 
a human hair; so- fine, indeed, that a single 
grain of silver maybe extended about 400 
feet in length. Its tenacity is such, that a 
wire of silver 0.078 inch in diameter is capa- 
ble of supporting a weight of 187. 131bs. avoir-* 
dupois without breaking. 
