(1.) Print-on the fat resist; (2.) dip in the blue vat, and dry; (3.)
ground-in the fat resist; (4.) pad in the logwood liquor, and dry; (5.)
mandarine, and steep for an hour; (6.) cleanse, and give the brightening
boil with soap.
This style of manufacture may be executed on chalys; and is capable of
producing beautiful effects, which will in vain be sought for by other
means.
With silks, advantage may be derived from various metallic solutions
which possess the property of staining animal substances; among which
are nitrate of silver, nitrate of mercury, and muriate of iron. The
solutions of these salts may be thickened with gum, and printed-on.
_An orange upon an indigo vat ground._--After the blue ground has been
dyed, orange figures may be produced by printing-on the following
discharge paste:--
1 gallon of water, made into a paste with 1 pound of starch: when cold,
add to it from 16 to 24 ounces of nitric acid, of spec. grav. 1·288.
After fixing the colour by steam, the orange is brightened with a soap
boil.
_An orange upon a Prussian-blue ground._--The dye is first given by
Prussian blue in the ordinary way, and then the following discharge is
printed-on:--
A caustic lye being prepared, of 1·086 specific gravity, dissolve in a
gallon of it 2 pounds of annotto, and thicken with 3 pounds and a
quarter of gum. Two days after the impression of this paste, pass the
goods through steam, and wash them in running water. With these two
designs, the logwood and gall black, formerly described, may be
associated, to produce a rich effect.
To the preceding practical instructions for printing calicoes, silks,
woollens, and mixed fabrics, made of the two latter, a few annotations
may be added.
When an uniform colour is to be applied to both sides of the cloth, the
padding process is employed; but, when only one side is to be thus
coloured, diagonal lines are cut very closely to each other upon the
cylinder, which transfer so much colour from the trough to the cloth
passed under it as to make the surface appear uniformly stained. This
process is called _mattage_ by the French. Mordants or topical dyes, to
be applied in this way, should not be much thickened.
The _doubler_ is the piece of felt or blanket stuff placed between the
cloth to be printed, and the block printing table, or the cylinders. It
should be kept very clean; because, were it soiled with acetate of iron,
it would spoil all the light shades made with acetate of alumina.
Filters for the colour shop of a print house are best made of wool,
formed into a substantial conical cap by felting. A filter ought to be
set apart for each different dye stuff.
When the goods after dyeing are washed, by being held by the selvage,
dipped, and shaken in a stream of water, the process is called _giving a
list_ by the French (_donner une lisière_). The piece is transferred
alternately from one hand to another.
_Stains._ When we observe stains produced by mordants, upon spots where
no colour is to come, we must, before dunging the goods, apply a little
of the lime juice, or tartaro-oxalic acid discharge paste, to the place.
If, on the contrary, the stains are not perceived till after the
maddering, we must then apply to it first a strong solution of chloride
of lime with a pencil, next a solution of oxalic acid mixed with a
little muriatic with another pencil, and immediately afterwards wash
with water. Every madder stain will be effaced by this means.
Rust stains are removable by a mixture of oxalic and muriatic acids.
Indigo stains by the combined action of chloride of lime and muriatic
acid.
Topical yellow stains, or yellow dyes, by the same combination.
Metallic greens and Scheele’s green by the acid alone.
Chrome green, and Prussian blue. The blue may be taken out by a caustic
alkali; after which the goods must be washed: the residuary rust stain
may be removed by the mixture of oxalic and muriatic acids. The above
methods refer to cotton and linen. The stains on silk and woollen stuffs
should be removed before fixing the colours by the soap boil; which may
generally be done by scratching with the finger, with the aid of a
little water.
For a direct calico green, see oxide of CHROME.
Mr. Hudson, of Gale, near Rochdale, obtained a patent, in December,
1834, for a mechanism which furnishes a continual and regular supply of
colour to the sieve or tear (_tiré_, Fr.) into which the printer has to
dip his block, for the purpose of receiving the colour about to be
transferred to the fabric in the operations of printing calicoes or
paper hangings. The contrivance consists in a travelling endless web,
moved by power, which, by passing progressively from the colour vat over
the diaphragm, brings forward continuously an equable supply of the
coloured paste for the workman’s block.
[Illustration: 251]
_Fig._ 251. represents the construction of this ingenious apparatus,
shown partly in section. _a a_ is a vessel of iron, supported upon
wooden standards _b b_, over the upper surface of which vessel a sheet
or diaphragm, _c c_, of oiled cloth, or other suitable elastic material,
is distended, and made fast at its edges by being bent over a flange,
and packed or cemented to render the joints water-tight. A vertical pipe
_d_ is intended to conduct water to the interior of the vessel _a_, and,
by a small elevation of the column, to create such upward pressure as
shall give to the diaphragm a slight bulge like the swimming tub.
An endless web, _e e e_, passing over the surface of the diaphragm, is
distended over three rollers, _f g h_, the lower of which, _f_, is in
contact with the colour-roller _i_ in the colour-trough K. On the axle
of the roller _i_ a pulley wheel is fixed, which allows the roller to be
turned by a band from any first mover; or the roller may receive
rotatory motion by a winch fixed on its axle. On this said axle there is
also a toothed wheel, taking into another toothed wheel on the axle of
the roller _f_; hence, the rotation of the colour-roller _i_ in the one
direction will cause the roller _f_ to revolve in the opposite, and to
carry forward the endless web _e e e_, over the elastic diaphragm, the
web taking with it a stratum of colour received from the roller _i_,
evenly distributed over its surface, and ready for the printer to dip
his block into.
The axles of the rollers _f_ and _g_ turn in stationary bearings; but
the axle of _h_ is mounted in sliding nuts, which may be moved by
turning the screws _m_, for the purpose of tightening the endless web.
The axle of the colour-roller _i_ turns in mortises, and may be raised
by screws _n_, in order to bring its surface into contact with the
endless web. To prevent too great a quantity of colour being taken up,
the endless web passes through a long slit, or parallel aperture, in a
frame _o_, which acts as a scraper or doctor, and is adjustable by a
screw _p_, to regulate the quantity of colour carried up. The contents
of the vessel _a_, and of the colour-trough K, may be discharged when
required by a cock in the bottom of each. See PAPER HANGINGS, for the
_Fondu_ style.
CALOMEL. (_Chlorure de Mercure_, Fr.; _Versüsstes Quecksilber_, Germ.)
The mild protochloride of mercury. The manufacture of this substance
upon the great scale may be performed in two ways. The cheapest and most
direct consists in mixing 1-1/8 part of pure quicksilver with 1 part of
pure nitric acid, of sp. grav. from 1·2 to 1·25; and in digesting the
mixture till no more metal can be dissolved, or till the liquid has
assumed a yellow colour. At the same time, a solution of 1 part of
common salt is made in 32 parts of distilled water, to which a little
muriatic acid is added; and, when heated to nearly the boiling point, it
is mixed with the mercurial solution. The two salts exchange bases, and
a protochloride of mercury precipitates in a white powder, which, after
being digested for some time in the acidulous supernatant liquor, is to
be washed with the greatest care in boiling water. The circumstances
which may injure the process are the following:--1. When less mercury is
employed than the acid can dissolve, there is formed a deuto-nitrate of
mercury, which forms some corrosive sublimate with the common salt, and
causes a proportional defalcation of calomel. 2. If the liquors are
perfectly neutral at the moment of mixing them, some subnitrate of
mercury is thrown down, which cannot be removed by washing, and which
gives a noxious contamination to the bland calomel. The acid prescribed
in the above formula obviates this danger.
The second manner of manufacturing calomel is to grind very carefully 4
parts of corrosive sublimate (bi-chloride of mercury) with 3 parts of
quicksilver, adding a little water or spirits to repress the noxious
dust during the trituration. The mass is then introduced into a glass
globe, and sublimed at a temperature gradually raised. The quicksilver
combines with the deutochloride, and converts it into the protochloride,
or calomel. The following formula, upon the same principle, was
recommended to the chemical manufacturer in Brande’s Journal, for July,
1818:--
“Prepare an oxysulphate of mercury, by boiling 25 pounds of mercury with
35 pounds of sulphuric acid to dryness. Triturate 31 pounds of this dry
salt with 20 pounds 4 ounces of mercury, until the globules disappear,
and then add 17 pounds of common salt. The whole is to be thoroughly
mixed, and sublimed in earthen vessels. Between 46 and 48 pounds of pure
calomel are thus produced: it is to be washed and levigated in the usual
way.” The above is the process used at Apothecaries’ Hall, London. The
oxysulphate is made in an iron pot; and the sublimation is performed in
earthen vessels. The crystalline crust or cake of calomel should be
separated from the accompanying gray powder, which is nearest the glass,
and consists of mercury mixed with corrosive sublimate.
An ingenious modification of the latter process, for which a patent, now
expired, was obtained by Mr. Jewell, consists in conducting the sublimed
vapours over an extensive surface of water contained in a covered
cistern. The calomel thus obtained is a superior article, in an
impalpable powder, propitious to its medical efficacy.
The presence of corrosive sublimate in calomel is easily detected by
digesting alcohol upon it, and testing the decanted alcohol with a drop
of caustic potash, when the characteristic brick-coloured precipitate
will fall, if any of the poisonous salt be present. To detect subnitrate
of mercury in calomel, digest dilute nitric acid on it, and test the
acid with potash, when a precipitate will fall in case of that
contamination. As it is a medicine so extensively administered to
children at a very tender age, its purity ought to be scrupulously
watched.