The Colours and Spectrum of Water

Abstract

A PERUSAL of the articles which have appeared in your journal on this subject (NATURE, vol. lxxxiii., pp. 48, 68, 188, 487, and vol. lxxxiv., p. 87) leads me to ask if the spectrum of water has ever been thoroughly investigated. It is difficult to believe that this has not been done, and yet there is but little allusion to the important bearing the character of the spectrum must have upon the colour. I should be glad to learn what is the origin of a feature I have sometimes observed in the spectrum, as seen with a “miniature spectroscope” by Browning. This is a dark band or line at about wave-length 6000, which I noticed in June, 1887, in Sark, in clear water, both in the sea and in fresh water. The latter was bluish-green, and the sea was green. So far as this line would have any influence on the colour of the water, it would tend to make it blue; but the colour would be much more influenced by the very strong general absorption in the whole of the red and orange beyond the dark line. In the sea water this general absorption extended more feebly to the D line of the solar spectrum, and even to the dryair bandδ.