Inquiries on the Causes of the Color of the Water of the Rhine24
269. I do not think the causes of the color of transparent water have been sufficiently ascertained. I do not mean that effect of color which is simply optical, as the color of the sea, which is regulated by the sky above or the state of the atmosphere, but I mean the settled color of transparent water, which has, when analyzed, been found pure. Now, copper will tinge water green, and that very strongly; but water thus impregnated will not be transparent, and will deposit the copper it holds in solution upon any piece of iron which may be thrown into it. There is a lake in a defile on the northwest flank of Snowdon, which is supplied by a stream which previously passes over several veins of copper; this lake is, of course, of a bright verdigris green, but it is not transparent. Now the coloring effect, of which I speak, is well seen in the water of the Rhone and Rhine. The former of these rivers, when it enters the Lake of Geneva, after having received the torrents descending from the mountains of the Valais, is fouled with mud, or white with the calcareous matter which it holds in solution. Having deposited this in the Lake Leman25 (thereby gradually forming an immense delta), it issues from the lake perfectly pure, and flows through the streets of Geneva so transparent, that the bottom can be seen twenty feet below the surface, jet so blue, that you might imagine it to be a solution of indigo. In like manner, the Rhine, after purifying itself in the Lake of Constance, flows forth, colored of a clear green, and this under all circumstances and in all weathers. It is sometimes said that this arises from the torrents which supply these rivers generally flowing from the glaciers, the green and blue color of which may have given rise to this opinion; but the color of the ice is purely optical, as the fragments detached from the mass appear white. Perhaps some correspondent can afford me information on the subject.
J. R.26
March, 1834.
Footnotes
Notes
24 From London’s Magazine of Natural History (London, Longmans & Co., 1834), vol. vii., No. 41, pp. 438-9, being its author’s earliest contribution to literature.—Ed.
25 This lake, however, if the poet have spoken truly, is not very feculent:—
“Lake Leman woos me with its crystal face,
The mirror where the stars and mountains view
The stillness of their aspect in each trace
Its clear depth yields of their far height and hue.”
Byron.
26 In the number of the magazine in which this note appeared was an article by “E. L.” on the perforation of a leaden pipe by rats, upon which, in a subsequent number (Vol. vii., p. 592), J. R. notes as follows: “E. S. has been, surely, too inattentive to proportions: there is an inconsistency in the dimensions of a leaden pipe about 1¼ in. in external diameter, with a bore of about ¾ in. in diameter; thus leaving a solid circumference of metal varying from ½ in. to ¾ in. in thickness.—J. R., Sept. 1834.”—Ed.