Works of Johann Wolfgang von Goethe
Page 314
527
How far, however, a kind of sub-oxydation may co-operate in some culminations, is matter for inquiry; for an influence of alkalis on the yellow-red also appears to produce the culmination; the colour reaching the acme by being forced towards the minus side.
528
The Dutch prepare a colour known by the name of vermilion, from the best Hungarian cinnabar, which exhibits the brightest yellow-red. This vermilion is still only a cinnabar, which, however, approximates the pure red, and it may be conjectured that alkalis are used to bring it nearer to the culminating point.
529
Vegetable juices, treated in this way, offer very striking examples of the above effects. The colouring-matter of turmeric, annotto, dyer’s saffron, and other vegetables, being extracted with spirits of wine, exhibits tints of yellow, yellow-red, and hyacinth-red; these, by the admixture of alkalis, pass to the culminating point, and even beyond it to blue-red.
530
No instance of a culmination on the minus side has come to my knowledge in the mineral and vegetable kingdoms. In the animal kingdom the juice of the murex is remarkable; of its augmentation and culmination on the minus side, we shall hereafter have occasion to speak.
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XL. Fluctuation.
531
The mutability of colour is so great, that even those pigments, which may have been considered to be defined and arrested, still admit of slight variations on one side or the other. This mutability is most remarkable near the culminating point, and is effected in a very striking manner by the alternate employment of acids and alkalis.
532
To express this appearance in dyeing, the French make use of the word “virer,” to turn from one side to the other; they thus very adroitly convey an idea which others attempt to express by terms indicating the component hues.
533
The effect produced with litmus is one of the most known and striking of this kind. This colouring substance is rendered red-blue by Means of alkalis. The red-blue is very readily changed to red-yellow by means of acids, and again returns to its first state by again employing alkalis. The question whether a culminating point is to be discovered and arrested by nice experiments, is left to those who are practised in these operations. Dyeing, especially scarlet-dyeing, might afford a variety of examples of this fluctuation.
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XLI.Passage Through the Whole Scale.
534
The first excitation and gradual increase of colour take place more on the plus than on the minus side. So, also, in passing through the whole scale, colour exhibits itself most on the plus side,
535
A passage of this kind, regular and evident to the senses, from yellow through red to blue, is apparent in the colouring of steel.
536
The metals may be arrested at various points of the colorific circle by various degrees and kinds of oxydation.
537
As they also appear green, a question arises whether chemists know any instance in the mineral kingdom of a constant transition from yellow, through green, to blue, and’ vice versa. Oxyde of iron, melted with glass, produces first a green, and with a more powerful heat, a blue colour.
538
We may here observe of green generally, that it appears, especially in an atomic sense, and certainly in a pure state, when we mix blue and yellow: but, again, an impure and dirty yellow soon gives us the impression of green; yellow and black already produce green; this, however, is owing to the affinity between black and blue. An imperfect yellow, such as that of sulphur, gives us the impression of a greenish hue: thus, again, an imperfect blue appears green. The green of wine bottles arises, it appears, from an imperfect union of the oxyde of iron with the glass. If we produce a more complete union by greater heat, a beautiful blue-glass is the result,
539
From all this it appears that a certain chasm exists in nature between yellow and blue, the opposite characters of which, it is true, may be done away atomically by due immixture, and, thus combined, to green; but the true reconciliation between yellow and blue, it seems, only takes place by means of red.
540
The process, however, which appears unattainable in inorganic substances, we shall find to be possible when we turn our attention to organic productions; for in these, the passage through the whole circle from yellow, through green and blue, to red, really takes place.
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XLII. Inversion.
541
Again, an immediate inversion of change to the totally opposite hue, is a very remarkable appearance which sometimes occurs; at present, we are merely enabled to adduce what follows.
542
The mineral chameleon, a name which has been given to an oxyde of manganese, may be considered, in its perfectly dry state, as a green powder. If we strew it in water, the green colour displays itself very beautifully in the first moment of solution, but it changes presently to the bright red opposite to green, without any apparent intermediate state.
543
The same occurs with the sympathetic ink, which may be considered a reddish liquid, but which, when dried by warmth, appears as a green colour on paper.
544
In fact, this phenomenon appears to be owing to the conflict between a dry and moist state, as has been already observed, if we are not mistaken, by the chemists. We may look to the improvements of time to point out what may further be deduced from these phenomena, and to show what other facts they may be connected with.
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XLIII. Fixation.
545
Mutable as we have hitherto found colour to be, even as a substance, yet under certain circumstances it may at last be fixed.
546
There are bodies capable of being entirely converted into colouring matter: here it may be said that the colour fixes itself in its own substance, stops at a certain point, and is there defined. Such colouring substances are found throughout nature; the vegetable world affords a great quantity of examples, among which some are particularly distinguished, and may be considered as the representatives of the rest; such as, on the active side, madder, on the passive side, indigo.
547
In order to make these materials available in use, it is necessary that the colouring quality in them should be intimately condensed, and the tinging substance refined, practically speaking, to an infinite divisibility. This is accomplished in various ways, and particularly by the well-known means of fermentation and decomposition.
548
These colouring substances now attach themselves again to other bodies. Thus, in the mineral kingdom they adhere to earths and metallic oxydes; they unite in melting with glasses; and in this case, as the light is transmitted through them, they appear in the greatest beauty, while an eternal duration may be ascribed to them,
549
They fasten on vegetable and animal bodies with more or less power, and remain more or less permanently; partly owing to their nature, — as yellow, for instance, is more evanescent than blue, — or owing to the nature of the substance on which they appear. They last less in vegetable than in animal substances, and even within this latter kingdom there are again varieties. Hemp or cotton threads, silk or wool, exhibit very different relations to colouring substances.
550
Here comes into the account the important operation of employing mordants, which may be considered as the intermediate agents between the colour and the recipient substance; various works on dyeing speak of this circumstantially. Suffice it to have alluded to processes by ‘means of which the colour retains a permanency only to be destroyed with the substance, and which may even increase in brightness and beauty by use.
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XLIV. Intermixture, Real.
551
EVERY intermixture pre-supposes a specific state of colour; and thus when
we speak of intermixture, we here understand it in. an atomic sense. We must first have before us certain bodies arrested at any given point of the colorific circle, before we can produce gradations by their union.
552
Yellow, blue, and red, may be assumed as pure elementary colours, already existing; from these, violet, orange, and green, are the simplest combined results.
553
Some persons have taken much pains to define these intermixtures more accurately, by relations of number, measure, and weight, but nothing very profitable has been thus accomplished.
554
Painting consists, strictly speaking, in the intermixture of such specific colouring bodies and their infinite possible combinations — combinations which can only be appreciated by the nicest, most practised eye, and only accomplished under its influence.
555
The intimate combination of these ingredients is effected, in the first instance, through the most perfect comminution of the material by means of grinding, washing, &c., as well as by vehicles or liquid mediums which hold together the pulverized substance, and combine organically, as it were, the unorganic; such are the oils, resins, &c. — Note V.
556
If all the colours are mixed together they retain their general character as , and as they are no longer seen next each other, no completeness, no harmony, is experienced; the result is grey, which, like apparent colour, always appears somewhat darker than white, and somewhat lighter than black.
557
This grey may be produced in various ways. By mixing yellow and blue to an emerald green, and then adding pure red, till all three neutralize each other; or, by placing the primitive and intermediate colours next each other in a certain proportion, and afterwards mixing them.
558
That all the colours mixed together produce white, is an absurdity which people have credulously been accustomed to repeat for a century, in opposition to the evidence of their senses.
559
Colours when mixed together retain their original darkness. The darker the colours, the darker will be the grey resulting from their union, till at last this grey approaches black. The lighter the colours the lighter will be the grey, which at last approaches white.
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XLV. Intermixture, Apparent.
560
The intermixture, which is only apparent, naturally invites our attention in connexion with the foregoing; it is in many respects important, and, indeed, the intermixture which we have distinguished as real, might be considered as merely apparent. For the elements of which the combined colour consists are only too small to be considered as distinct parts. Yellow and blue powders mingled together appear green to the naked eye, but through a magnifying glass we can still perceive yellow and blue distinct from each other. Thus yellow and blue stripes seen at a distance, present a green mass; the same observation is applicable with regard to the intermixture of other specific colours.
561
In the description of our apparatus we shall have occasion to mention the wheel by means of which the apparent intermixture is produced by rapid movement. Various colours are arranged near each other round the edge of a disk, which is made to revolve with velocity, and thus by having several such disks ready, every possible intermixture can be presented to the eye, as well as the mixture of all colours to grey, darker or lighter, according to the depth of the tints as above explained.
562
Physiological colours admit, in like manner, of being mixed with others. If, for example, we produce the blue shadow (65) on a light yellow paper, the surface will appear green. The same happens with regard to the other colours if the necessary preparations are attended to.
563
If, when the eye is impressed with visionary images that last for a while, we look on coloured surfaces, an intermixture also takes place; the spectrum is determined to a new colour which is composed of the two.
564
Physical colours also admit of combination. Here might be adduced’ the experiments in which many-coloured images are seen through the prism, as we have before shown in detail (258, 284).
565
Those who have prosecuted these inquiries have, however, paid most attention to the appearances which take place when the prismatic colours are thrown on coloured surfaces.
566
What is seen under these circumstances is quite simple. In the first place it must be remembered that the prismatic colours are much more vivid than the colours of the surface on which they are thrown. Secondly, we have to consider that the prismatic colours may be either homogeneous or heterogeneous, with the recipient surface. In the former case the surface deepens and enhances them, and is itself enhanced in return, as a coloured stone is displayed by a similarly coloured foil. In the opposite case each vitiates, disturbs, and destroys the other.
567
These experiments may be repeated with coloured glasses, by causing the sun-light to shine through them on coloured surfaces. In every instance similar results will appear.
568
The same effect takes place when we look on coloured objects through coloured glasses; the colours being thus according to the same conditions enhanced, subdued, or neutralized.
569
If the prismatic colours are suffered to pass through coloured glasses, the appearances that take place are perfectly analogous; in these cases more or less force, more or less light and dark, the clearness and cleanness of the glass are all to be allowed for, as they produce many delicate varieties of effect: these will not escape the notice of every accurate observer who takes sufficient interest in the inquiry to go through the experiments.
570
It is scarcely necessary to mention that several coloured glasses, as well as oiled or transparent papers, placed over each other, may be made to produce and exhibit every kind of intermixture at pleasure.
571
Lastly, the operation of glazing in painting belongs to this kind of intermixture; by this means a much more refined union may be produced than that arising from the mechanical, atomic mixture which is commonly employed.
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XLVI. Communication, Actual.
572
Having now provided the colouring materials, as before shown, a further question arises how to communicate these to colourless substances: the answer is of the greatest importance from the connexion of the object with the ordinary wants of men, with useful purposes, and with commercial and technical interests.
573
Here, again, the dark quality of every colour again comes into the account. From a yellow that is very near to white, through orange, and the hue of minium to pure red and carmine, through all gradations of violet to the deepest blue which is almost identified with black, colour still increases in darkness. Blue once defined, admits of being diluted, made light, united with yellow, and then, as green, it approaches the light side of the scale: but this is by no means according to its own nature.
574
In the physiological colours we have already seen that they are less than the light, inasmuch as they are a repetition of an impression of light, nay, at last they leave this impression quite as a dark. In physical experiments the employment of semi-transparent mediums, the effect of semi-transparent accessory images, taught us that in such cases we have to do with a subdued light, with a transition to darkness,
575
In treating of the chemical origin of pigments we found that the same effect was produced on the very first excitement. The yellow tinge which mantles over the steel, already darkens the shining surface. In changing white lead to massicot it is evident that the yellow is darker than white.
576
This process is in the highest degree delicate; the growing intenseness, as it still increases, tinges the substance more and more intimately and powerfully, and thus indicates the extreme fineness, and the infinite divisibility of the colour
ed atoms.
577
The colours which approach the dark side, and consequently, blue in particular, can be made to approximate to black; in fact, a very perfect Prussian blue, or an indigo acted on by vitriolic acid appears almost as a black.
578
A remarkable appearance may be here’ adverted to; pigments, in their deepest and most condensed state, especially those produced from the vegetable kingdom, such as the indigo just mentioned, or madder carried to its intensest hue, no longer show their own colour; on the contrary, a decided metallic shine is seen on their surface, in which the physiological compensatory colour appears,
579
All good indigo exhibits a copper-colour in its fracture, a circumstance attended to, as a known characteristic, in trade. Again, the indigo which has been acted on by sulphuric acid, if thickly laid on, or suffered to dry so that neither white paper nor the porcelain can appear through, exhibits a colour approaching to orange.
580
The bright red Spanish rouge, probably prepared from madder, exhibits on its surface a perfectly green, metallic shine. If this colour, or the blue before mentioned, is washed with a pencil on porcelain or paper, it is seen in its real state owing to the bright ground shining through.
581
Coloured liquids appear black when no lightis transmitted through them, as we may easily see in cubic tin vessels with glass bottoms. In these every transparent-coloured infusion will appear black and colourless if we place a black surface under them.
582
If we contrive that the image of a flame be reflected from the bottom, the image will appear coloured. If we lift up the vessel and suffer the transmitted light to fall on white paper under it, the colour of the liquid appears on the paper. Every light ground seen through such a coloured medium exhibits the colour of the medium.
583
Thus every colour, in order to be seen, must have a light within or behind it. Hence the lighter and brighter the grounds are, the more brilliant the colours appear. If we pass lac-varnish over a shining white metal surface, as the so-called foils are prepared, the splendor of the colour is displayed by this internally reflected light as powerfully as in any prismatic experiment; nay, the force of the physical colours is owing principally to the circumstance at light is always acting with and behind the