other persons the impression is not visual, but may belong to a different sense. It may be sonorous; in some persons the sight of colors gives a musical impression; or it may be tactile, and sight and hearing may be accompanied by mechanical sensations. In short, all imaginable combinations of different sensations may be realized.
In colored audition the impressions of color are almost exclusively provoked by speech; the sounds and noises of Nature producing the same effect only by a kind of analogy with the human voice. Speech gives him who hears it an impression of color only when the emission is full; a murmur has not the effect of the singing voice or of a reading in public; the height of the tone influences the shadings; barytone and bass voices excite dark sensations and high voices light ones. On a closer examination of the source of the phenomenon it is found that the color, while it may borrow a general tint from the timbre of the voice, and consequently from the individuality of the speaker, depends more especially upon the words that are pronounced; each word has its peculiar color, or we might rather say colors, for some words have five or six; pushing the analysis further, we perceive that the color of words depends on that of the component letters, and that it is therefore the alphabet which is colored; and, finally, that the consonants have only pale and washed-out tints, and the coloration of language is derived directly from the vowels. With a few exceptions this is true for all the subjects.
By a curious complication produced by education, the appearance of colors takes place in some persons not only when they hear the word pronounced or when they think of it, but even when they see it written. There are also persons who do not perceive the color except while they are reading. Many facts, however, seem to prove that reading is generally of no effect except as a suggestion of the spoken word, and therefore constitutes a kind of audition.
The observations on the colors of the vowels in detail are irregular and contradictory. Thus, a, red to one, is black to another, white to a third, yellow to a fourth, and so on; the whole spectrum passes through it; but as the number of colors and of letters is limited, we can, by analyzing a hundred observations, meet two or three among them that will agree. Sometimes agreement is manifested between members of the same family, or between persons who live together; but waiving the instances afforded by chance, by heredity, and by suggestion, it remains evident that disagreement is the general rule; and from this curious practical effects follow. Two persons having colored audition, when brought together, are not able to understand one another; each is greatly surprised at the colors which the other perceives, and we