M. Ch. Martins on the Colour of the Ice of Glaciers. 87 



In order to throw some light on tho question, let us now consider 

 the colour of the water of glaciers in a state of repose, where it is 

 accumulated in great masses in the lakes of Switzerland. The lake 

 of Geneva, fed principally by the waters of the Rhone, which come 

 from all the glaciers of the Valais, is, it is true, of a beautiful azure 

 blue ; but the lake of Brientz, which receives the waters of glaciers 

 exclusively, is of a very deep pistachio-green. This tint is equally 

 strikinfT, when we view it from the summit of the Faulhorn, that is to 

 fiay, 2120 metres above its level, or only from a few metres above its 

 surface. M. Bravais and myself have observed that, for entire weeks, 

 this tint varies only very little, according to the light. The circum- 

 stance which proves decidedly that these tints are independent of tho 

 glacier origin of the tributaries is, that the lake of Thun, receiving 

 its waters from the lake of Brientz, with which it comnmnicates across 

 the isthmus of Interlaken, is of a blue colour, sometimes equalling that 

 of the lake of Geneva. The small Gelmersee, fed by the glaciers of 

 tho Geemerhorn, is pistachio-green, like the lake of Brientz. I may 

 mention, besides, the lake of Kloenthal, in the Canton of Glaris. 

 " One can scarcely distinguish it," says M. Baoul-Rochette, in his 

 Lettres sur la Swisse, "from the meadow surrounding it; for its 

 waters are of the same colour as the adjoining grass." This lake is 

 fed by the glaciers of Glaernisch anduhe melted snow of Pragel. 

 The small lake near the hospice of Grimsel is of a sombre tint ; others 

 are more or less blue ; and this variability of hue proves that the 

 character assigned by Ebel and Durocher to the waters of glaciers is 

 subject to such numerous exceptions, that it loses all scientific value. 



In order to finish this demonstration, let us turn our attention to 

 the colour of the waters of glaciers when they make their escape in 

 the form of rivers, from the lakes in which they have deposited the 

 impurities with which they were charged. Nothing can equal tho 

 azure of the waters of the Bhone when they issue from the lake of 

 Geneva ; they form a striking contrast with the grey and muddy 

 waves of the Arve, which comes directly from the glaciers of Cha- 

 monix. The only example cited by M. Dnrocher is of the same kind ; 

 he refers to the Otta-Elv, a river of Guldbrandsdal, a valley of 

 Southern Norway. This river traverses four lakes in succession be- 

 fore receiving the tributary of Lougen-Elv. It is not therefore sur- 

 prising that its waters, purified in passing through these four basins, 

 contrast in their blue colours, with the waters of the Lougen-Elv ; 

 this is exactly the case of the Arve and Rhone at their junction below 

 Geneva. Both of them come from glaciers ; but the Rhone, grey like 

 the Arve when it enters the lake of Geneva, is blue when it leaves 

 it, because it is freed f\'om its impurities. The Arve continues turbid, 

 because it passes through no lake in its course. The following is 

 the last fact we shall mention, as affording a still stronger proof that 

 the blue colour is not inherent in the water of glaciers : At tho top 

 of the valley of Kaudersteg (ca^tpn of Berne), 1568 metres above the 



