﻿MM. SCHLAGINTWEIT ON THE ALPS. 



15 



Among the numerous points of interest offered to the geologist 

 in the chapters above enumerated, the glaciers, their formation, mo- 

 tion, and effects, have a high place. The memoir* on the Phi/ steal 

 Characters of Ice by M. Hermann Schlagintweit (pp. 1-25) shows 

 that : — 1 . in their crystalline structure, glacier- and water-ice, under 

 the alternate influence of heat and cold, resolve themselves into quite 

 identical forms : — 2. the air-bubbles enclosed in the ice especially par- 

 ticipate in the formation of the crystals, and exert an influence on the 

 form of all free surfaces: — 3. the distinctly crystalline formation reaches, 

 with the exception of the blue bands, a maximum depth of 3 metres ; 

 infiltration, however, in irregularly distributed canals and capillary 

 chinks penetrates still deeper : — 4. the air enclosed in the white ice 

 amounts, on an average, to 6 per cent, of the whole volume of the 

 mass : — 5. the water of thawing ice absorbs air to saturation : — 6. the 

 air absorbed by the water is richer in oxygen than the atmosphere, 

 whilst that freed from the melting ice (the portion not absorbed) is 

 poorer in that respect : — 7. the blue colour of the depths in snow, gla- 

 ciers, and ice does not arise from the reflection of the firmament above, 

 but is the peculiar colour of water in a fixed condition ; in the mean 

 it is identical with a mixture of 74*9 per cent, of Kremser-white 

 [white-lead], 24*3 per cent, cobalt, and 0*8 per cent, of burnt ochre ; 

 being, therefore, always lighter than the blue of the atmosphere in the 

 zenith for mid-latitudes : — 8. ice exhibits throughout the properties of 

 a hard and even a dry body ; and the interstitial moveability [ver- 

 schiebbarkeit] cf the mass, recognized in a glacier from its structure 

 and motion, appears to arise from the fine splintering of the ice, caused 

 by the pressure of enormous masses and their friction against the 

 underlying rock. 



The conclusions arrived at by M. Hermann Schlagintweit in the 

 second chapter (pp. 26-47) in regard to the Regions of granular snow 

 [Firn-regionen], and from his researches on snow, granular snow [Firn, 

 or Neve], the passage of " firn" into ice, &c, are : — 1. the extent of 

 the field or sea of granular snow [firn-meer] is in general greater 

 than that of the glacier belonging to it : — 2. the altitude of the lowest 

 places where "firn" is met with in the Alps sometimes does not 

 exceed 2500 feet (French) ; but its existence is limited also by great 

 elevation, since it becomes converted into the more icy masses [sum- 

 mit-ice, or Hoch-eis] at the height of more than 1 1,000 feet [French] : 

 — 3. the snow always becomes the more crystalline, and at the same 

 time the more difficult to thaw, the older it is : — 4. the region of the 

 dust-snow avalanches [Staublawinen] commences above the limits of 

 the forests, and continues downwards only in some cases to the " mon- 

 tane region" : — 5. the marking of the "firn-meer" by snow-disks 

 [Schnee-radchen] is only superficial, but it shows that even slightly 

 inclined firn-seas are composed of much smaller basins : — 6. the "firn" 

 or neve is generally laminated ; an annual layer is from 0*75 to 

 1 metre in depth : — 7. with few exceptions, there are no glaciers on 

 limestone ; the most essential conditions for the formation of glaciers 

 are wide basins and an underlying rock impenetrable to water. 

 * Originally communicated to Poggendorf's Annal. Physik u. Chem. 



