294 Report of the Besearches vf M. Agassiz, 



if the infiltrated water congeals in the interior of the glacier, 

 and thereby determines its movement, this congelation is not 

 owing to the nocturnal cold, as was believed both by M. 

 Charpentier and by M. Agassiz. On this point, the result 

 of our observations last year quite agree with the opinion 

 of Professor Forbes : a subject to which we shall ere long re- 

 turn. But our experiments upon infiltration were not con- 

 fined to the hard and compact ice of the glaciers, properly so 

 called ; they were also repeated upon the neve and upon the 

 ice of the neve, and with results equally satisfactory. The 

 true neve, composed of incoherent snow particles, could be 

 impregnated with water in no other than in a uniform way. 

 But it is more important to observe, that the adhering or con- 

 nected neve, in other words, that dull and opaque ice which 

 forms the substratum of the neve, and which we call the 

 ice of the neve, imbibes water in precisely the same manner. 

 In it we find no capillary fissures as in compact ice, serving as 

 canals to the infusion ; but it spreads throughout the whole 

 mass, almost as in a porous rock, and with much greater ra- 

 pidity than in the ice of a glacier, properly so called. More- 

 over, the compact ice itself also presents very marked differ- 

 ences in the rapidity with which it is stained by the colouring- 

 liquids. It often happened that we bored many holes near 

 each other, and observed that the liquid was absorbed in some 

 in a very short time, whilst it remained much longer in others. 

 Struck by this difference, we investigated its cause, and dis- 

 covered that those holes which rapidly became empty had 

 been sunk in bands of blue ice, whilst those which long re- 

 tained the impression were bored in the white ice. Hence the 

 difference clearly appeared to be a natural consequence of the 

 structure of the blue ice, which is traversed with many more 

 fissures than the white. In this particular, we find we are 

 directly opposed to the statement of Professor Forbes, who 

 mentions that it is the white bands that especially subserve 

 the purpose of infiltration. It is true, that in proportion as 

 the white ice loses its air-bubbles, in other words, becomes 

 water-ice, glace d^eau, by the infiltration of the surface-water, 

 its net- work of fissures increases, and finally it allows the 

 transudation of the liquid as rapidly as the blue ice ; but this 



