On the Colour of the Water of Glaciers. 337 



fact, that an account of our experiment and its results had 

 already been published by a friend in the Supplement to the 

 Gazette d'Augsbourg on 17th September 1846; {Beylage, 

 zur AlgGmeinen deutsichen Zeitung, No. 260, p. 2079) and 

 consequently two weeks before Mr Forbes' account ap- 

 peared. 



Ch. Martins, D. M. & G. 



Paris, Quai de Bethune, 1847. 



On the Colour of the Water of Glaciers. By M. Ed. Collomb. 



I have had occasion, many times, to observe the waters of 

 the torrents which issue from the principal glaciers of Swit- 

 zerland ; those of the two Grindelwalds, the Rosenlaui, the 

 lower and upper Aar, the glacier of the Rhone, that of 

 Viesch, Aletsch, Hinter Rhein, the valley of Saas, and the 

 valley of Chamouni. In no instance that has come under 

 my observation have the waters proceeding immediately from 

 the melting of the glaciers presented a blue tint ; I say im- 

 mediatelg, because we can now speak only of the water as 

 examined at a short distance from glaciers. After it has 

 traversed a considerable space, spring-water becomes min- 

 gled with it, and when it is collected in a tranquil basin, 

 forming a lake, it is no longer the water of the glacier, but 

 has undergone important modifications. Its constitution 

 and colour are no longer the same. 



On issuing from the glacier, the water is always turbid 

 and milky ; it is never limpid, as MM. Agassiz and Ch. 

 Martins have already remarked ; and, with respect to colour, 

 it is always of a greyish hue. This tint, well known to ob- 

 servant artists, varies infinitely ; its scale is very extensive, 

 from greenish-grey to bluish-grey or yellowish-grey, with a 

 great variety of shades. The colour of this water is subject 

 to atmospheric influences ; during rain, it is not of the same 

 hue as in clear weather. I could judge of the variations in 

 colour it undergoes, while making a series of regular observa- 



