lieport of the Eesearches of M. Agassiz, 311 



4. Observations on the pretended Purity of Ice, 



Continued researches often lead to the invalidation of opi- 

 nions which are very generally adopted. It is a prevailing 

 opinion with the mountaineers, and from them has found its 

 way as an undoubted dogma into the works of naturalists and 

 natural philosophers, that the ice of the glaciers is perfectly 

 pure. This alleged purity is even become proverbial in some 

 countries ; and from the time of Scheuchzer and De Saussure, 

 down to that of Charpentier and Agassiz, every one was for- 

 ward to confirm it. When in the clear atmosphere of the 

 high Alps, under the serenest sky, we contemplate those walls 

 and vaults, whose lustre rivals the bright azure of the firma- 

 ment, we readily persuade ourselves that the ice which com- 

 poses them must be perfectly pure. And notwithstanding, if 

 we reflect upon it, we shall find that we have no plausible 

 room for admitting the absolute purity of the ice of the gla- 

 ciers. A long sojourn amidst the ice of the Alps can alone 

 reveal to us the true state of matters, and inform us of the 

 imperfections and intimate defects of the glacier, for this ice, 

 so exceedingly transparent, has its own share of impurities. 

 In the year 1840, when we visited the grotto at the extremity 

 of the upper glacier of Grindelwald, we discovered, not without 

 surprise, a rolled pebble in the midst of the ice, and M. Agas- 

 siz directed the surrounding ice to be carefully removed, that, 

 if possible, we might learn how it had been introduced. But 

 we discovered absolutely nothing which gave us the slightest 

 information on the point ; the surrounding ice exhibited no- 

 thing particular ; and as there was only this single pebble in 

 the whole surrounding mass, we inferred it had probably fallen 

 into a crevice which subsequently was closed up.* 



M. Escher de la Linth was the first who shook our confi- 

 dence on this point, by informing us he had seen in the glacier 

 of Viesch large pebbles embedded in very pure ice. Never- 

 theless, we did not arrive at the knowledge of the true state 

 of matters till the year 1842. In cutting a drain near the 

 Hotel des Neuchdtelois^ we noticed that one of the blue bands 



* [See Bibl. Universelle for April 18 il, vol. xxxii. p. 3o»« 



