1804. Compare with the "Trattato della Pittura," p. 141. Other points

of resemblance are to be met with. The notion of certain colours appropriated to the four elements, occurs in Aristotle, and is indeed attributed to older writers. [9] See the notes to the Roman edition of the "Trattato della Pittura." [10] Page 237. [11] Page 301. [12] In the Treatise _De Igne_, by Theophrastus, we find the same notion thus expressed: "Brightness (_τὸ λευκὸν_) seen through a dark coloured medium (_διὰ του μέλανος_) appears red; as the sun seen through smoke or soot: hence the coal is redder than the flame." Scarmiglione, from whom Kircher seems to have copied, observes:--"Itaque color realis est lux opaca; licet id e plurimis apparentiis colligere. Luna enim in magnâ solis eclipsi rubra conspicitur, quia tenebris lux præpeditur ac veluti tegitur."--_De Coloribus_. [13] Page 122. [14] _Τὰ ἂνθη_: translated _flores_ by Calcagnini and the rest, by Goethe, _die Blüthe_, the bloom. That the word sometimes signified pigments is sufficiently apparent from the following passage of Suidas (quoted by Emeric David, "Discours Historiques sur la Peinture Moderne") _ἂνθεσι κεκοσμημέναι, οἶον ψιμμιωίῳ φύκει καὶ τοῖς ὸμοίοις_. Variis pigmentis ornatæ, ut cerussâ, fuco, et aliis similibus. (Suid. in voc. _Ἐξμηθισμένας_.) A panel prepared for painting, with a white ground consolidated with wax, and perhaps mastic, was found in Herculaneum. [15] Page 114. [16] _Ἐν βάθει δὲ θεωρουμίνου ιγγυτάτω φαίνεται τῶ χρώματι κυανονοειδὴς διὰ τὴν ὰραιότητα._ "But when seen in depth, it appears (even) in its nearest colour, blue, owing to its thinness." The Latin interpretations vary very much throughout. The point which is chiefly important is however plain enough, viz. that darkness seen through a light medium is blue. [17] Page 136-430. [18] Page 121, 306, 326, 387. [19] Page 306. [20] Page 104, 369. [21] Page 236, 260, 328. [22] "De' semplici colori il primo è il bianco: beuchè i filosofi non accettano nè il bianco nè il nero nel numero de' colori."--p. 125, 141. Elsewhere, however, he sometimes adopts the received opinion. [23] Leon Battista Alberti, in like manner observes:--"Affermano (i filosofi) che le spezie de' colori sono sette, cioè, che il bianco ed il nero sono i duoi estremi, infra i quali ve n'è uno nel mezzo (rosso) e che infra ciascuno di questi duoi estremi e quel del mezzo, da ogni parte ve ne sono due altri." An absurd statement of Lomazzo, p. 190, is copied verbatim from Lodovico Dolce (Somma della Filos. d'Arist.); but elsewhere, p. 306, Lomazzo agrees with Alberti. Aristotle seems to have misled the two first, for after saying there are seven colours, he appears only to mention six: he says--"There are seven colours, if brown is to be considered equivalent to black, which seems reasonable. Yellow, again, may be said to be a modification of white. Between these we find red, purple, green, and blue."--_De Sensu et Sensili_. Perhaps it is in accordance with this passage that Leonardo da Vinci reckons eight colours.--_Trattato_, p. 126. [24] Page 122, 142, 237. [25] On the authority of this explanation the word μιλάν has sometimes been translated in the foregoing extracts _obscurity, darkness_. Raffaello Borghini, in his attempt to describe the doctrine of Aristotle with a view to painting, observes--"There are two principles which concur in the production of colour, namely, light and transparence." But he soon loses this clue to the best part of the ancient theory, and when he has to speak of the derivation of colours from white and black, he evidently understands it in a mere atomic sense, and adds--"I shall not at present pursue the opinion of Aristotle, who assumes black and white as principal colours, and considers all the rest as intermediate between them."--_Il Riposo_, 1. ii. Accordingly, like Lodovico Dolce, he proceeds to a subject where he was more at home, namely, the symbolical meaning of colours. [26] This word is only strictly applied to unctuous substances, and may confirm the views of those writers who have conjectured that asphaltum was a chief ingredient in the _atramentum_ of the ancients. [27] "Elements of Physiology," by J. Müller, M.D., translated from the German by William Baly, M.D. London, 1839. NOTE N.--Par. 246. "The appearance of white in the centre, according to the Newtonian theory, arises from each line of rays forming its own spectrum. These spectra, superposing each other on all the middle part, leave uncorrected (unneutralised) colours only at the two edges."--S. F.[1] [1] This was objected to Goethe when his "Beyträge sur Optik" first appeared; he answered the objection by a coloured diagram in the plates to the "Farbenlehre:" in this he undertakes to show that the assumed gradual "correction" of the colours would produce results different from the actual appearance in nature. NOTE O.--Par. 252. These experiments with grey objects, which exhibit different colours as they are on dark or light grounds, were suggested, Goethe tells us, by an observation of Antonius Lucas, of Lüttich, one of Newton's opponents, and, in the opinion of the author, one of the few who made any well-founded objections. Lucas remarks, that the sun acts merely as a circumscribed image in the prismatic experiments, and that if the same sun had a lighter background than itself, the colours of the prism would be reversed. Thus in Goethe's experiments, when the grey disk is on a dark ground, it is edged with blue on being magnified; when on a light ground it is edged with yellow. Goethe acknowledges that Lucas had in some measure anticipated his own theory.--Vol. ii. p. 440. NOTE P.--Par. 284. The earnestness and pertinacity with which Goethe insisted that the different colours are not subject to different degrees of refrangibility are at least calculated to prove that he was himself convinced on the subject, and, however extraordinary it may seem, his conviction appears to have been the result of infinite experiments and the fullest ocular evidence. He returns to the question in the controversial division of his work, in the historical part, and again in the description of the plates. In the first he endeavours to show that Newton's experiment with the blue and red paper depends entirely on the colours being so contrived as to appear elongated or curtailed by the prismatic borders. "If," he says, "we take a light-blue instead of a dark one, the illusion (in the latter case) is at once evident. According to the Newtonian theory the yellow-red (red) is the least refrangible colour, the violet the most refrangible. Why, then, does Newton place a blue paper instead of a violet next the red? If the fact were as he states it, the difference in the refrangibility of the yellow-red and violet would be greater than in the case of the yellow-red and blue. But here comes in the circumstance that a violet paper conceals the prismatic borders less than a dark-blue paper, as every observer may now easily convince himself," &c.--Polemischer Theil, par. 45. Desaguliers, in repeating the experiment, confessed that if the ground of the colours was not black, the effect did not take place so well. Goethe adds, "not only not so well, but not at all."--Historischer Theil, p. 459. Lucas of Lüttich, one of Newton's first opponents, denied that two differently-coloured silks are different in distinctness when seen in the microscope. Another experiment proposed by him, to show the unsoundness of the doctrine of various refrangibility, was the following:--Let a tin plate painted with the prismatic colours in stripes be placed in an empty cubical vessel, so that from the spectator's point of view the colours may be just hidden by the rim. On pouring water into this vessel, all the colours become visible in the same degree; whereas, it was contended, if the Newtonian doctrine were true, some colours would be apparent before others.--Historischer Theil, p. 434. Such are the arguments and experiments adduced by Goethe on this subject; they have all probably been answered. In his analysis of Newton's celebrated _Experimentum Crucis_, he shows again that by reversing the prismatic colours (refracting a dark instead of a light object), the colours that are the most refrangible in Newton's experiment become the least so, and _vice versâ_. Without reference to this objection, it is now admitted that "the difference of colour is not a test of difference of refrangibility, and the conclusion deduced by Newton is no longer admissible as a general truth, that to the same degree of refrangibility ever belongs the same colour, and to the same colour ever belongs the same degree of refrangibility."--Brewster's Optics, p. 72. NOTE Q--Par. 387. With the exception of two very inconclusive letters to Sulpice Boisserée, and some incidental observations in the conclusion of the historical portion under the head of entoptic colours, Goethe never returned to the rainbow. Among the plates he gave the diagram of Antonius de Dominis. An interesting chapter on halos, parhelia, and paraselenæ, will be found in Brewster's Optics, p. 270. NOTE R.--Par. 478. The most complete exhibition of the colouring or mantling of metals was attained by the late Cav. Nobili, professor of physical science in Florence. The general mode in which these colours are produced is thus explained by him:[1]-- "A point of platinum is placed vertically at the distance of about half a line above a lamina of the same metal laid horizontally at the bottom of a vessel of glass or porcelain. Into this vessel a solution of acetate of lead is poured so as to cover not only the lamina of platinum, but two or three lines of the point as well. Lastly, the point is put in communication with the negative pole of a battery, and the lamina with the positive pole. At the moment in which the circuit is completed a series of coloured rings is produced on the lamina under the point similar to those observed by Newton in lenses pressed together." The scale of colours thus produced corresponds very nearly with that observed by Newton and others in thin plates and films, but it is fuller, for it extends to forty-four tints. The following list, as given by Nobili, is divided by him into four series to agree with those of Newton: the numbers in brackets are those of Newton's scale. The Italian terms are untranslated, because the colours in some cases present very delicate transitions.[2] _First Series._