Grains.
Paste 2880
Oxide of manganese 72
_Emerald._
Paste 4608
Green oxide of pure copper 42
Oxide of chrome 2
_Sapphire._
Paste 4608
Oxide of cobalt 68
This mixture should be carefully fused in a luted Hessian crucible, and
be left 30 hours in the fire.
_Amethyst._
Grains.
Paste 4608
Oxide of manganese 36
Oxide of cobalt 24
Purple of Cassius 1
_Syrian Garnet, or Antient Carbuncle._
Paste 512
Glass of Antimony 256
Cassius purple 2
Oxide of manganese 2
_Beryl, or Aqua Marina._
Paste 3456
Glass of antimony 24
Oxide of cobalt 1-1/2
In all these mixtures, the substances should be mixed by sifting, fused
very carefully, and cooled very slowly, after having been left in the
fire from 24 to 30 hours.
M. Lançon has also made many experiments on the same subject. The
following are a few of his proportions:--
_Paste._
Grains.
Litharge 100
White sand 75
White tartar, or potash 10
_Amethyst._
Paste 9216
Oxide of manganese from 15 to 24
Oxide of cobalt 1
_Emerald._
Paste 9216
Acetate of copper 72
Peroxide of iron, or saffron of Mars 1·5
PASTILLE, is the English name of small cones made of gum benzoin, with
powder of cinnamon, and other aromatics, which are burned as incense, to
diffuse a grateful odour, and conceal unpleasant smells in apartments.
See PERFUMERY.
PASTILLE, is the French name of certain aromatic sugared confections;
called also _tablettes_.
PEARLASH, a commercial form of POTASH, which see.
PEARLS (_Perles_, Fr.; _Perlen_, Germ.); are the productions of certain
shell-fish. These molluscæ are subject to a kind of disease caused by
the introduction of foreign bodies within their shells. In this case,
their pearly secretion, instead of being spread in layers upon the
inside of their habitation, is accumulated round these particles in
concentric layers. Pearl consists of carbonate of lime, interstratified
with animal membrane.
The oysters whose shells are richest in mother of pearl, are most
productive of these highly prized spherical concretions. The most
valuable pearl fisheries are on the coast of Ceylon, and at Olmutz in
the Persian Gulf, and their finest specimens are more highly prized in
the East than diamonds, but in Europe they are liable to be rated very
differently, according to the caprice of fashion. When the pearls are
large, truly spherical, reflecting and decomposing the light with much
vivacity, they are much admired. But one of the causes which renders
their value fluctuating, is the occasional loss of their peculiar
lustre, without our being able to assign a satisfactory reason for it.
Besides, they can be now so well imitated, that the artificial pearls
have nearly as rich an appearance as the real.
PEARLS, ARTIFICIAL. These are small globules or pear-shaped spheroids of
thin glass, perforated with two opposite holes, through which they are
strung, and mounted into necklaces, &c., like real pearl ornaments. They
must not only be white and brilliant, but exhibit the iridescent
reflections of mother of pearl. The liquor employed to imitate the
pearly lustre, is called the _essence of the east_ (_essence d’orient_),
which is prepared by throwing into water of ammonia the brilliant
scales, or rather the _lamellæ_, separated by washing and friction, of
the scales of a small river fish, the blay, called in French _ablette_.
These scales digested in ammonia, having acquired a degree of softness
and flexibility which allow of their application to the inner surfaces
of the glass globules, they are introduced by suction of the liquor
containing them in suspension. The ammonia is volatilized in the act of
drying the globules.
It is said that some manufacturers employ ammonia merely to prevent the
alteration of the scales; that when they wish to make use of them, they
suspend them in a well clarified solution of isinglass, then pour a drop
of the mixture into each bead, and spread it round the inner surface. It
is doubtful whether by this method, the same lustre and play of colours
can be obtained as by the former. It seems moreover to be of importance
for the success of the imitation, that the globules be formed of a
bluish, opalescent, very thin glass, containing but little potash and
oxide of lead. In every manufactory of artificial pearls, there must be
some workmen possessed of great experience and dexterity. The French are
supposed to excel in this ingenious branch of industry.
PEARLWHITE, is a submuriate of bismuth, obtained by pouring a solution
of the nitrate of that metal into a dilute solution of sea salt, whereby
a light and very white powder is obtained, which is to be well washed
and dried. See BISMUTH.
PECTIC ACID (_Acid pectique_, Fr.; _Gallertsaüre_, Germ.); so named on
account of its jellying property, from πηκτις, _coagulum_, exists in a
vast number of vegetables. The easiest way of preparing it, is to grate
the roots of carrots into a pulp, to express their juice, to wash the
_marc_ with rain or distilled water, and to squeeze it well; 50 parts of
the marc are next to be diffused through 300 of rain-water, adding by
slow degrees a solution of one part of pure potash, or two of
bicarbonate. This mixture is to be heated, so as to be made to boil for
about a quarter of an hour, and is then to be thrown boiling-hot upon a
filter cloth. It is known to have been well enough boiled, when a sample
of the filtered liquor becomes gelatinous by neutralizing it with an
acid. This liquor contains pectate of potassa, in addition to other
matters extricated from the root. The pectate may be decomposed by a
stronger acid, but it is better to decompose it by muriate of lime;
whereby a pectate of lime, in a gelatinous form, quite insoluble in
water, is obtained. This having been washed with cold water upon a
cloth, is to be boiled in water containing as much muriatic acid as will
saturate the lime. The pectic acid thus liberated, remains under the
form of a colourless jelly, which reddens litmus paper, and tastes sour,
even after it is entirely deprived of the muriatic acid. Cold water
dissolves very little of it; it is more soluble in boiling water. The
solution is colourless, does not coagulate on cooling, and hardly
reddens litmus paper; but it gelatinizes when alcohol, acids, alkalis,
or salts are added to it. Even sugar transforms it, after some time,
into a gelatinous state, a circumstance which serves to explain the
preparation of apple, cherry, raspberry, gooseberry, and other jellies.
PECTINE, or vegetable jelly, is obtained by mixing alcohol with the
juice of ripe currants, or any similar fruit, till a gelatinous
precipitate takes place; which is to be gently squeezed in a cloth,
washed with a little weak alcohol, and dried. Thus prepared, pectine is
insipid, without action upon litmus, in small pieces, semi-transparent,
and of a membranous aspect, like isinglass. Its mucilaginous solution in
cold water is not tinged blue with iodine. A very small addition of
potash, or its carbonate, converts pectine into pectic acid; both of
which substances are transformed into mucic and oxalic acids by the
nitric.
PELTRY (_Pelleterie_, Fr.; _Pelzwerk_, Germ.); is nearly synonymous with
fur, and comprehends the skins of different kinds of wild animals that
are found in high northern latitudes, particularly in the American
continent; such as the beaver, bear, moosedeer, marten, mink, sable,
woolverin, wolf, &c. When these skins have received no preparation but
from the hunters, they are most properly called peltry; but when they
have had the inner side tawed or tanned (see LEATHER) by an aluminous
process, they may then be denominated _furs_.
The scouring or cleaning of peltry is performed in a large cask, or
truncated cone laid on its side, and traversed by a revolving shaft,
which is furnished with a few rectangular rounded pegs. These are
intended to stir round the skins, while they are dusted over with Paris
plaster, whitening, or sometimes sand, made as hot as the hand can bear.
The bottom of the cask should be grated, to allow the impurities to fall
out. The _lustrage_, which the cleansed skins next undergo, is merely a
species of dyeing, either topical to modify certain disagreeable shades,
or general to impart a more beautiful colour to the fur. Under the
articles DYEING, and the several colours, as also HAIR and MOROCCO,
sufficient instructions will be found for dyeing fur. The mordants
should be applied pretty hot by a brush, on the hair of the skin,
stretched upon a solid table; and after two or three applications, with
drying between, the tinctorial infusions may be rubbed on in the same
way. The hair must be freed beforehand from all greasiness, by lime
water, or a weak solution of carbonate of soda; then well washed. Much
nicety, and many successive applications of the dye-stuff, are sometimes
requisite to bring out the desired shade.
Under HAT MANUFACTURE, I referred to this article for a description of
the process of _secrétage_, whereby the hairs of rabbit and hare skins
are rendered fit for felting. Dissolve 32 parts of quicksilver in 500 of
common aquafortis; and dilute the solution with one half or two thirds
of its bulk of water, according to the strength of the acid. The skin
being laid upon a table with the hair side uppermost, a brush, made with
the bristles of the wild boar, is to be slightly moistened with the
mercurial solution, and passed over the smooth surface of the hairs with
strong pressure. This application must be repeated several times in
succession, till every part of the fur be equally touched, and till
about two thirds of the length of the hairs be moistened, or a little
more, should they be rigid. In order to complete this impregnation, the
skins are laid together in pairs with the hairy sides in contact, put in
this state into the stove-room, and exposed to a heat higher in
proportion to the weakness of the mercurial solution. The drying should
be rapidly effected, otherwise the concentration of the nitrate will not
take due effect in causing the retraction and curling of the hairs.
No other acid, or metallic solution, but the above, has been found to
answer the desired purpose of the hatmaker. After the hairs are properly
_secreted_, they are plucked off by hand, or shorn off by a machine.
PENCIL MANUFACTURE. (_Crayons, fabrique de_, Fr.; _Bleistifte,
verfertigung_, Germ.) The word pencil is used in two senses. It
signifies either a small hair brush employed by painters in oil and
water colours, or a slender cylinder of black lead or plumbago, either
naked or enclosed in a wooden case, for drawing black lines upon paper.
The last sort, which is the one to be considered here, corresponds
nearly to the French term crayon, though this includes also pencils made
of differently coloured earthy compositions. See CRAYON.
The best black-lead pencils of this country are formed of slender
parallelopipeds, cut out by a saw from sound pieces of plumbago, which
have been previously calcined in close vessels at a bright red heat.
These parallelopipeds are generally enclosed in cases made of cedar
wood, though of late years they are also used alone, in peculiar
pencil-cases, under the name of ever-pointed pencils, provided with an
iron wire and screw, to protrude a minute portion of the plumbago beyond
the tubular metallic case, in proportion as it is wanted.
In the year 1795, M. Conté, a French gentleman, well acquainted with the
mechanical arts, invented an ingenious process for making artificial
black-lead pencils of superior quality, by which he and his successor
and son-in-law, M. Humblot, have realized large fortunes.
Pure clay, or clay containing the smallest proportion of calcareous or
siliceous matter, is the substance which he employed to give aggregation
and solidity, not only to plumbago dust, but to all sorts of coloured
powders. That earth has the property of diminishing in bulk, and
increasing in hardness, in exact proportion to the degree of heat it is
exposed to, and hence may be made to give every degree of solidity to
crayons. The clay is prepared by diffusing it in large tubs through
clear river water, and letting the thin mixture settle for two minutes.
The supernatant milky liquor is drawn off by a syphon from near the
surface, so that only the finest particles of clay are transferred into
the second tub, upon a lower level. The sediment which falls very slowly
in this tub, is extremely soft and plastic. The clear water being run
off, the deposit is placed upon a linen filter, and allowed to dry. It
is now ready for use.
The plumbago must be reduced to a fine powder in an iron mortar, then
put into a crucible, and calcined at a heat approaching to whiteness.
The action of the fire gives it a brilliancy and softness which it would
not otherwise possess, and prevents it from being affected by the clay,
which it is apt to be in its natural state. The less clay is mixed with
the plumbago, and the less the mixture is calcined, the softer are the
pencils made of it; the more clay is used the harder are the pencils.
Some of the best pencils made by M. Conté, were formed of two parts of
plumbago and three parts of clay; others of equal parts. This
composition admits of indefinite variations, both as to the shade and
hardness; advantages not possessed by the native mineral. While the
traces may be made as black as those of pure plumbago, they have not
that glistening aspect which often impairs the beauty of black-lead
drawings. The same lustre may, however, be obtained by increasing the
proportion of powdered plumbago relatively to the clay.
The materials having been carefully sifted, a little of the clay is to
be mixed with the plumbago, and the mixture is to be triturated with
water into a perfectly uniform paste. A portion of this paste may be
tested by calcination. If on cutting the indurated mass, particles of
plumbago appear, the whole must be further levigated. The remainder of
the clay is now to be introduced, and the paste is to be ground with a
muller upon a porphyry slab, till it be quite homogeneous, and of the
consistence of thin dough. It is now to be made into a ball, put upon a
support, and placed under a bell glass inverted in a basin of water, so
as to be exposed merely to the moist air.
Small grooves are to be made in a smooth board, similar to the pencil
parallelopipeds, but a little longer and wider, to allow for the
contraction of volume. The wood must be boiled in grease, to prevent the
paste from sticking to it. The above described paste being pressed with
a spatula into these grooves, another board, also boiled in grease, is
to be laid over them very closely, and secured by means of screw-clamps.
As the atmospheric air can get access only to the ends of the grooves,
the ends of the pencil-pieces become dry first, and by their contraction
in volume get loose in the grooves, allowing the air to insinuate
further, and to dry the remainder of the paste in succession. When the
whole piece is dried, it becomes loose, and might be turned out of the
grooves. But before this is done, the mould must be put into an oven
moderately heated, in order to render the pencil pieces still drier. The
mould should now be taken out, and emptied upon a table covered with
cloth. The greater part of the pieces will be entire, and only a few
will have been broken, if the above precautions have been duly observed.
They are all, however, perfectly straight, which is a matter of the
first importance.
In order to give solidity to these pencils, they must be set upright in
a crucible till it is filled with them, and then surrounded with
charcoal powder, fine sand, or sifted wood ashes. The crucible, after
having a luted cover applied, is to be put into a furnace, and exposed
to a degree of heat regulated by the pyrometer of Wedgewood; which
degree is proportional to the intended hardness of the pencils. When
they have been thus baked, the crucible is to be removed from the fire,
and allowed to cool with the pencils in it.
Should the pencils be intended for drawing architectural plans, or for
very fine lines, they must be immersed in melted wax or suet nearly
boiling hot, before they are put into the cedar cases. This immersion is
best done by heating the pencils first upon a gridiron, and then
plunging them into the melted wax or tallow. They acquire by this means
a certain degree of softness, are less apt to be abraded by use, and
preserve their points much better.
When these pencils are intended to draw ornamental subjects with much
shading, they should not be dipped as above.
_Second process for making artificial pencils, somewhat different from
the preceding._--All the operations are the same, except that some
lamp-black is introduced along with the plumbago powder and the clay. In
calcining these pencils in the crucible, the contact of air must be
carefully excluded, to prevent the lamp-black from being burned away on
the surface. An indefinite variety of pencils, of every possible black
tint, may thus be produced, admirably adapted to draw from nature.
Another ingenious form of mould is the following:
Models of the pencil-pieces must be made in iron, and stuck upright upon
an iron tray, having edges raised as high as the intended length of the
pencils. A metallic alloy is made of tin, lead, bismuth, and antimony,
which melts at a moderate heat. This is poured into the sheet-iron tray,
and after it is cooled and concreted, it is inverted, and shaken off
from the model bars, so as to form a mass of metal perforated throughout
with tubular cavities, corresponding to the intended pencil-pieces. The
paste is introduced by pressure into these cavities, and set aside to
dry slowly. When nearly dry, the pieces get so much shrunk that they may
be readily turned out of the moulds upon a cloth table. They are then to
be completely desiccated in the shade, afterwards in a stove-room, next
in the oven, and lastly ignited in the crucible, with the precautions
above prescribed.
M. Conté recommends the hardest pencils of the architect to be made of
lead melted with some antimony and a little quicksilver.
In their further researches upon this subject, M. Conté and M. Humblot
found that the different degrees of hardness of crayons could not be
obtained in a uniform manner by the mere mixture of plumbago and clay in
determinate doses. But they discovered a remedy for this defect in the
use of saline solutions, more or less concentrated, into which they
plunged the pencils, in order to modify their hardness, and increase the
uniformity of their texture. The non-deliquescent sulphates were
preferred for this purpose; such as sulphate of soda, &c. Even syrup was
found useful in this way.
PENS, STEEL. The best metal, made from Dannemora or hoop (L) iron, is
selected, and laminated into slips about 3 feet long, and 4 inches
broad, of a thickness corresponding to the desired stiffness and
flexibility of the pens. These slips are subjected to the action of a
stamping-press, somewhat similar to that for making buttons. (See
BUTTON, and PLATED WARE.) The point destined for the nib is next
introduced into an appropriate gauged hole of a little machine, and
pressed into the semi-cylindrical shape; where it is also pierced with
the middle slit, and the lateral ones, provided the latter are to be
given. The pens are now cleaned, by being tossed about among each other,
in a tin cylinder, about 3 feet long, and 9 inches in diameter; which is
suspended at each end upon joints, to two cranks, formed one on each of
two shafts. The cylinder, by the rotation of a flywheel, acting upon the
crank-shafts, is made to describe such revolutions as agitate the pens
in all directions, and polish them by mutual attrition. In the course of
4 hours several thousand pens may be finished upon this machine.
PEPPER. (_Poivre_, Fr.; _Pfeffer_, Germ.), Black pepper is composed,
according to M. Pelletier, of the vegetable principle, _piperine_, of a
very acrid concrete oil, a volatile balsamic oil, a coloured gummy
matter, an extractive principle analogous to legumine, malic and
tartaric acids, starch, bassorine, ligneous matter, with earthy and
alkaline salts in small quantity. Cubebs pepper has nearly the same
composition.
Pepper imported for home consumption,
in 1835, 1836, 1837.--Duty 6_d._ per lb.
Lbs. 2,359,573; 2,800,980; 2,626,298.
PERFUMERY, ART OF (_Parfumerie_, Fr.; _Wohlriechende-kunst_, Germ.);
consists in the preparation of different products, such as fats or
pommades, essential oils, distilled spirits, pastes, pastilles, and
essences.
Fats ought to be pounded in a marble mortar, without addition of water,
till all the membranes be completely torn; then subjected to the heat of
a water-bath in a proper vessel. The fat soon melts, and the albumen of
the blood coagulating, carries with it all the foreign substances; the
liquid matter should be skimmed, and passed through a canvas filter.
_Of pommades by infusion._--Rose, orange-flower, and cassia. Take 334
pounds of hog’s lard, and 166 of beef suet. These 500 pounds are put
into a pan called _bugadier_; and when melted, 150 pounds of rose-leaves
nicely plucked are added, taking care to stir the mixture every hour.
The infusion thus prepared is to remain at rest for 24 hours; at the end
of this time, the pommade is again melted, and well stirred to prevent
its adherence to the bottom of the melting-pan. The mass is now to be
poured out into canvas, and made into rectangular bricks or loaves,
which are subjected to a press, in order to separate the solid matter
from the soft pommade. These brick-shaped pieces being put into an
iron-bound barrel perforated all over its staves, the pommade is to be
allowed to exude on all sides, and flow down into a copper vessel placed
under the trough of the press. This manipulation should be repeated with
the same fat ten or twelve times; or in other words, 3000 pounds of
fresh rose-leaves should be employed to make a good pommade.
The pommade of orange-flowers is made in the same manner, as also the
pommade of cassia.
_Of pommades without infusion._--Jasmin, tuberose, jonquil, narcissus,
and violet.
A square frame, called _tiame_, is made of four pieces of wood, well
joined together, 2 or 3 inches deep, into which a pane of glass is laid,
resting upon inside ledges near the bottom. Upon the surface of the pane
the simple pommade of hog’s lard and suet is spread with a pallet knife;
and into this pommade the sweet-scented flowers are stuck fresh in
different points each successive day, during two or three months, till
the pommade has acquired the desired richness of perfume. The
above-described frames are piled closely over each other. Some
establishments at _Grasse_ possess from 3000 to 4000 of them.
_Of oils._--Rose, orange-flower, and cassia oils, are made by infusion,
like the pommades of the same perfumes; taking care to select oils
perfectly fresh. As to those of jasmin, tuberose, jonquil, violet, and
generally all delicate flowers, they are made in the following manner.
Upon an iron frame, a piece of cotton cloth is stretched, imbued with
olive oil of the first quality, and covered completely with a thin bed
of flowers. Another frame is similarly treated,--and in this way a pile
is made. The flowers must be renewed till the oil is saturated with
their odour. The pieces of cotton cloth are then carefully pressed to
extrude the oil. This last operation requires commonly 7 or 8 days.
_Of distillation._--The essential oils or essences, of which the great
manufacture is in the south of France, are of rose, neroli, lavender,
lemon thyme, common thyme, and rosemary. For the mode of distilling the
essential oils, see OILS, ESSENTIAL.
The essence of roses being obtained in a peculiar manner, I shall
describe it here. Put into the body of a still 40 pounds of roses, and
60 quarts of water; distil off one half of the water. When a
considerable quantity of such water of the first distillation is
obtained, it must be used as water upon fresh rose leaves; a process of
repetition to be carried to the fifth time. In the distillation of
orange-flower, to obtain the essence of neroli, the same process is to
be followed; but if orange-flower water merely be wanted, then it is
obtained at one distillation, by reserving the first fifth part of water
that comes over. What is called the essence of _petit-grain_, is
obtained by distilling the leaves of the orange shrub. The essences of
lavender, thyme, &c., present nothing peculiar in their mode of
extraction.