The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1838-10-26 00:00:00

LIVERPOOL MECHANICS' INSTITUTION.

LECTURES ON CHEMISTRY AS APPLIED TO THE ARTS,

On Saturday Dr. Kane brought his interesting course to
a close.
We have arrived at the examination of one of the most
important, but at the same time perhaps the most compli-
cated instance of the formation of an useful art on chemical
principles. The examination of the circumstances under
which we are enabled to fix colouring matter upon calicoes,
sand the ordinary textures which we- fear, we shall find to
bring us to the most beautiful results which chemical exami-
jiatiorkjuspointed out to 115. But.we shall find, at the same
time, that allhough considerable acivances have beeir Made
in the application of chemistry to these arts, yet many disco-
veries of great importance remain to be made; and we may
look forward to great improvements, when those engaged in
the pursuit of them shall have devoted themselves to the pur-
suit of chemical theory.
' Generally speaking, we-shall consider the theory of fixing
colours upon woven fabrics as being the same. It must de-
pend, as all chemical actions depend, upon the existence of
an affinity between the two substances: there must be a dis-
tinct alliance between them, so that they may remain in
combination. The degree of permanence which the colour
must possess will depend upon the strength of this union.
If the affinity be strong, the colour will be permanent; but
if it be weak, the tendency to remain united will not be so
perfect, and the colour will lose its brilliancy, and if it comes
into contact with soap, it will be completely decomposed.
In consequence, we have colours which are termed fugitive,
in opposition to those which are termed fixed. The instances
in which the fibre of the cloth has a direct tendency to unite
with the dyeing matters, are very few; and it is necessary
to make use of some intermediate substance, which has an
affinity for the fibre of the cloth and the colouring matter.
In such instances the intermediate substance is termed a
mordant, and the whole difficulty of the dyeing depends upon
these mordants, which are different for different colours and
different shades; and the soldering, therefore, of the colouring
matter- makes the case more complicated than the simple
process of dyeing would be. The majority of the colouring
matters are vegetable, or derived from the vegetable king-
dom; and in the majority of cases it is necessary to make
use of mordants. The fibres of cloth have a tendency to unite
with metallic oxides. Wherever a vegetable colouring mat-
ter is to be made use of. we have to employ a mordant,-and
this moidant is invariably a metallic oxide. The fibres of
cloth have a remarkable tendency to unite with the oxide of
iron, so much so that they will withdraw it from the solution
of any of its salts, and leave the acid behind. This is the
case with iron mould, which is the simple dyeing of any
article with oxide of iron. The oxide of iron fixed upon a
cloth gives rise, according to the degree of intensity, to the
different shades of buff. If I dip a piece of cotton cloth into
a solution of nitrate of iron, it will come out of a buff colour;
but the colour is not completely fixed upon the cloth, for the
oxide of iron would still remain to a considerable extent
united to nitric acid, and if the cloth were washed the great
mass of the colouring matter would wash away. In order
to fix the iron permanently upon the cloth, it is only neces-
sary to take some potash, or any other base, and we get a
deep buff, so that, however we wash it in water, there will
be no colouring matter removed. The oxide of iron is itself
a mordant, and not only unites with the fibres of the cloth
without the aid of any intermediate substance, but is itself
the bond of union between these fibres and other colouring
matters. In addition to the oxide of iron, I might bring
before you similar experiments with respect to the oxides of
alumina, the oxides of lead, and other mineral agents; but
in those cases where the cloth is saturated with these oxides,
the oxides themselves being white, the cloth is not dyed.
The oxide of iron being brown, gives those shades which are
intermediate between the lightest buff and a dark brown.
It is easy to shew the manner in which the oxide of
iron may become a mordant. It is only necessary to
take any one vegetable colouring matter whatever,—for
example, a little of the infusion of galls,—and if we im-
merse the cloth in it which has been coloured brown by the
oxide of iron, it will be turned completely black. One of
the most remarkable applications of iron as a mordant, con-
sists in the developement of a beautiful blue colour, which is
of vegetable origin, namely, prussian blue. ILI order to ge-
nerate it, we have only to add ferroprussic acid to the oxide
of iron. This is effected by ferroprussiate of potash, some
oil of vitriol being added to neutralize the potash. The cloth
being first dyed brown in the oxide of iron, is changed into
the intensely deep blue upon immersion into this liquor, and
the colour is tolerably fixed upon the cloth. It is not abso-
lutely fixed, but it is nearly so, and is accordingly used on
ordinary occasions. In this manner, what is called Naples
blue is produced upon silk, and a great variety of patterns
are printed with it upon cotton goods. There is an instance
of a still more remarkable character. We have here a piece
of cloth, prepared as cloths are for printing, with oxide of iron
in the state of a paste, by means of flour and gum, and this
paste having a certain degree of tenacity when stamped upon
the cloth, it has no tendency to run upon the cloth, and the
pattern is perfectly correct. By immersing the cloth in ferro-
prussiate of potash, the Prussian blue will not be generated
upon any other part but where the prepared iron was stamped.
In the majority of cases where you observe a beautiful deep
blue upon cloth, it has been produced by this means. I look
upon the formation of Prussian blue in this instance as an
example of the combination of an article of mineral origin
with one of animal. A very beautiful colour is generated by
the union of oxide of lead with chromic acid. The principle
of dyeing by chromate of potash, consists in the generation
of certain insoluble salts by means of chromic acid. Chromic
acid unites with many of the metallic oxides, and forms salts
which are insoluble in water. Thus, if we take the solution
of a salt of lead, and add to it a solution of chromate of pot-
ash, the result will be the production of a yellow precipitate,
of an exceedingly beautiful appearance. In the majority of
cases, where a fixed yellow is to be dyed, it is done by the
precipitation of the chromate of lead upon the fibres of the
cloth. The cloth is first impregnated in the oxide of lead,
and then immersed in a solution of chromate of potash, by
which we obtain a canary yellow, of an exceedingly bright
appearance. By the use of paste we can, in the same man-
ner as in the instance of Prussiau blue, cause any pattern to
be printed upon cloth with the chromate of lead. The chro-
mic acid is not merely useful in this preparation, but it may
be employed to produce another very remarkable colour upon
cloth. In addition to this, which is called the natural chro-
mate of lead, there is a chromate of lead which contains only
half the quantity of chromic acid, which is called a subchro-
mate of lead. When it is precipitated upon cloth, it pro-
duces an orange colour, and produces one of the most beauti-
ful colours of this kind which is used in the arts. In order
to produce this orange chrome, or the subchromate of lead,
the best method is to take the chromate of potash, and to add
an excess of alkali. In this way the cloth is impregnated
with potash in excess. By then placing it in a hot solution
of lead, there is chromate of lead formed ; but in consequence
of there being a great excess of potash, we have not merely
the yellow oxide, but a proportion of the red chromate, and
the two mixed together, give the different shades of orange,
which may be made by the manufacturer as be wishes. In
order to get a deeper shade of orange, we can get it by add-
ing more and more of the alkali, provided we do not add too
much, so as to destroy the colour altogether. The more we
use any article dyed in this manner, the more they will ap-
proach a red. A very beautiful case of the application of
the metallic oxide to cloths as the colouring matter, in which
the metallic oxide is itself the colouring material, is exem-
plified in the metal manganese. I have already pointed out
the exceeding similarity between the salts of manganese and
the salts of iron. Manganese possesses the property of
combining with oxygen in different proportions ; the first
oxide being white in a hydrated condition, and by com-
bining with acid, will give colourless solutions. if I add
to one of these colourless solutions a little potash, the
manganese is precipitated as a powder, a hich is at the first
perfectly white, but the protoxide of manganese basso power-
ful an affinity for oxygen as to extract a quantity front the
air, when it assumes a brownish colour, and if we supply it
with any substance capable of giving oxygen to it, the brown
colour will be still more deepened. Thus if we take some of
the chloride of lime, and add it to a solution of the protoxide
of manganese, the solution will become a deep brown. This
action of chloride of lime is very peculiar. We have already
had to describe chlorine and the chlorine of lime as bleaching
materials, and now we find them to act in an opposite way.
The principle of action is, however, the same in both in •
stances, chlorine giving oxygen by the decomposition of
water. It is in this way that the manganese bronzes as they
are called are generated in the arts. The oxide of manganese
being thus of a dark bronze colour you will understand how,
when it is mixed with the cotton fibre, it gives the cotton a
shade similar to bronze. If I take a little of the colourless
solution of manganese and immerse a piece of white cloth
into it, the cloth will absorb a certain portion of the solution.
By immersing the cloth in the chloride of lime, which always
contains an excess of lime, the lime precipitates the oxide
of manganese, which, coming into contact with the chlorine,
is immediately raised to its highest degree of oxydation, so
that the cloth, which was before white, is brought to a bronze
brown condition. Manganese gives to us a complete de-
velopement of the theory of bleaching. It is colourless at its
least point of oxygenation, and coloured at its highest. If
we put it into contact with a substance which has a greater
affinity for oxygen than itself, it will take the oxygen from it
and bleach it. If we add a little of the protochlotide of tin,
which has a powerful affinity for oxygen to the peroxide of
manganese, the colour is immediately discharged. Not
merely are we enabled to do this by means of the solution,
but if we take a piece of cloth which has been bronzed by the
manganese, and put it into the peroxide of tin, the cloth is
immediately bleached,—the manganese being reduced from
the state of the peroxide to the state of protoxide. We are
thus enabled to bleach manganese by a solution of tin. This
property of tin in bleaching the solution of manganese is
made use of iu calico printing in a very ingenious way.
When a cloth dyed brown with manganese is to have a pat-
tern of white or of any other colour printed upon it, the cloth
is universally dyed brown in the first instance. The solution
of tin is mixed up into a paste, and with this mixture the
pattern is blocked in every place where the tin comes into
contact, the colour is discharged, and left perfectly white for
the application of other colours, if necessary. We arc not
yet able to print with madder locally, the aiticle to be co-
loured requiring to be dyed in a madder bath, and we are
therefore obliged to remove the madder red after the article
has been dyed in order to print upon the cloth. This is a
very important and complicated process, so much so, that
the discovery of any means of printing direct with madder
would be of the utmost value in the arts. The mode in which
it is effected is by blocking any pattern upon white calico with
a solution of tartaric or oxalic acid made into a paste with
flour, and then dying the calico entirely in madders. The
calico is then immersed in a solution of chloride of lime, when
the acid combines with the lime, and the chlorine discharges
the madder red from those portions of the cloth only where
the block had been applied, leaving the remainder untouched.
It is .worthy of remark that chloride of lime alone possesses
no bleaching properties, and only bleaches by contact with
acid.
The colouring matters derived from the vegetable kingdom
are exceedingly numerous. We may, however, reduce them
to the three prismatic colours, for we shall find that where
the wood or colouring matter gives rise to different shades,
it is owing to the existence of more than one colouring mat-
ter ; and it is the union of these different colouring matters
which give different results. I shall therefore consider them
tinder the head of red, yellow, and blue colours, which exist
in considerable numbers. One of the most useful, perhaps,
is that which is procured by means of the weil-known Persian
or Turkey berries. These contain a peculiar yellow colouring
matter, of a somewhat resinous nature, which, when treated
with an alkaline solution gives a deep yellow liquor. Like
all yellow colouring matters of vegetable origin it is turned
brown by the alkali • but it we take a small quantity of the
acid and add it to the alkali, the acid neutralizes the alkali,
and according as it does so, provided the acid be not used in
too much excess, the yellow colouring principle is strikingly
developed. The most important means of fixing the colour-
ing principle of the Persian bet ry on cloth is by means of tin,
and it is easy to ascertain the method in which this is dune.
If I take a little of the alkaline liquor, develope the colouring
principle by acid, and add to it the solution of tin, we get a
pure yellow precipitate, which is the substance which is ge-
nerated on the surface of the cloth when we make use of the
tin mordant in calico printing, which is a colour of extreme
beauty. A very excellent colour is given by means of the
acetate of lead, which has not yet been applied. There is a
fact connected with the use of Persian berries with which it
is important that you should be rendered familiar. This
berry is what is termed in the art a steam colour, that is, it
requires a very high temperature to bring it out, is of a beau-
tiful character. If you take some of the solution of the
.yellow
berries and plunge into it a cloth which is saturated with the
solution of alumina, we shall find that the cloth will be dyed
in a combination of the alumina with the colouring principle
of the berries. The alumina is a mordant, and one of the
most valuable which the printer has for affixing vegetable dyes.
Before leaving the constitution of the yellow principle of the
Persian berry, I shall notice the production upon cloth of
the same yellow lake which we have formed by means of tin.
The{-yellosv.colour formed by the tin is much finer and deeper
than that produced by the alumina. A yellow colouring
matter which is very extensively used, not so inuch•for the
purpose of producing fine yellows as for the production of an