88 On the Colour of IVater. 



sea, is the small lake of Oescliinen ; it is fed wholly by the waters which 

 fall in numerous cascades from the glaciers of the Doldenhorn. This 

 lake is of a deep green. Its outlet being subterranean, the waters pass 

 through the ground as through a filter ; they are limpid, transparent, 

 shewing no trace of blue, of a sombre tint in deep places, and remind 

 the spectator, in every point of view, of the pure and colourless waters 

 where cresses grow, and the small rivers of Normandy inhabited by 

 trouts. We perceive that, in this case, the waters furnished solely 

 by glaciers, and after a very short transit, do not exhibit the blue 

 tint either in a state of repose or motion.* 



On the Colour of Water. 



** I have," says Sir H. Davy, *' often thought upon the subject, and I 

 have made some observations and one experiment in relation to it. I 

 will give you my opinion with'pleasure, and, as far as I know, they have 

 not been brought forward in any of the works on the properties of water, 

 or on its consideration as a chemical element. The purest water with 

 which we are acquainted, is undoubtedly that which falls from the 

 atmosphere. Having toucl^d air alone, it can contain nothing but 

 what it gains from the atmosphere ; and it is distilled without the 

 chance of those impurities, which may exist in the vessels used in an 

 artificial operation. We cannot well examine the water precipitated 

 from the atmosphere, as rain, without collecting it in vessels, and all 

 artificial contact gives more or less of contamination. But in snow, 

 melted by the sunbeams, that has fallen on glaciers, themselves 

 formed from frozen snow, water may be regarded as in its greatest 

 state of purity. Congelation expels both salts and air from water, 

 whether existing below, or formed in, the atmosphere ; and in the 

 high and uninhabited regions of glaciers, there can scarcely be any 

 substances to contaminate. Removed from animal and vegetable 

 life, they are even above the mineral kingdom ; and though there are 

 instances in which the rudest kind of vegetation (of the fungus or 

 mucor kind) is even found upon snows, yet this is a rare occurrence, 

 and red snow, which is occasioned by it, is an extraordinary and not 

 a common phenomenon towards the pole, and on the highest moun- 

 tains of the globe. Having examined the water from melted snows 

 on glaciers in different parts of the Alps, and having always found 

 it of the same quality, I shall consider it as pure water, and describe 

 its characters. Its colour, when it has any depth, or when a mass 

 of it is seen through, is bright blue ; and according to its greater or 

 less depth of substance, it has more or less of this colour. As its in- 

 sipidity and its other physical qualities are not at this moment objects 



* Comptcs Kendus; No. 13, p. 545. 



