Researches on Existing Glaciers. 271 



half an hour the blue bands could only be vaguely distinguish- 

 ed from the white ones; the surface had assumed a very rough 

 aspect ; some hours afterwards it had even become entirely 

 porous to the depth of about an inch ; the lumps which were 

 formed had become mobile, without, however, being disag- 

 gregated; the differences of tint had then completely dis- 

 appeared, and the ice appeared composed of unequal but 

 homogeneous fragments. Nevertheless, by moistening large- 

 ly with water this unequal surface, the ribboned arrange- 

 ment and the tints of defined colour reappeared immediate- 

 ly, and anew gave to the ice the lamellar aspect which it 

 had originally. When the influence of the atmosphere was 

 prolonged for a considerable period, the white bands at 

 last became completely disaggregated to the depth of about 

 a foot, and were then transformed into small grains per- 

 fectly similar to those of the mvc, whereas the blue bands only 

 appeared between these beds of grains as projecting edges 

 soiled by the dust which lodges on glaciers. It is in the white 

 bands, which are originally hard, but have become granular 

 in consequence of the external temperature and the melting, 

 that the small rills of water collect, which wind over the sur- 

 face of the glacier. But if the glacier should be inundated 

 by a violent rain, on the following day its blue and white tints 

 at the surface contrast anew with a striking intensity. This, 

 at least, was what we saw take place last year, and it remains 

 to be ascertained to what extent this reiterated phenomenon 

 of disaggregation and of congelation is reproduced at different 

 seasons, and under influences of various kinds, and what are 

 the circumstances which render the whole more or less appa- 

 rent at the surface of the glacier. It is probable, according 

 to what has just been stated, that the white bands are a ncx'6 

 impregnated with water and congealed, whereas the blue bands 

 appear to me to be bands of ice of liquid water transformed 

 directly into homogeneous ice.* It is diihcult to determine 



* It would be interesting to ascertain if the same thing takes place ia ice 

 houses, coLtaining piled up ice which has been sprinkled with water. 



