Ancient Extent of the Glaciers of Chamonix, 85 



see the glacial period take its place ; let us hail the appear- 

 ance of this latter, for it has been revealed to us by the at- 

 tentive study of well observed facts, and not by vain specu- 

 lations of the fancy. Let us not renew the idle quarrelu of 

 the Neptunians and Vulcanists ; impartial posterity has de- 

 cided between them. They were equally wrong as impas- 

 sioned partisans of an exclusive idea ; each of them had rea- 

 son on their side by the facts and observations they brought 

 forward in support of their absolute theories. All existing 

 geologists are at once Vulcanists and Neptunians ; science 

 has taken the part of water and fire. It will be the same with 

 glaciers and currents. Both of them have played their part 

 in times past, and it is the same at the present time. The 

 phenomena have remained the same ; but, instead of those 

 gigantic manifestations, which is the character of the geolo- 

 gical epochs anterior to our own, they are included within 

 the limits of action imposed upon them by the equilibrium of 

 the period of repose which the appearance of man has intro- 

 duced to the earth. — From Bevue de Deux Mondes, t. xvii. 

 1st March 1847. 



On the Colour of the Ice of Glaciers, and that of the Waters 

 which flow from them. By M. Ch. Martins. 



At the meeting of tho 15th of March last, the Academy received 

 a communication from M. Darocher, entitled ^iMc?c5 surles Glaciers 

 du Nord et du centre de V Europe. This note contains some asser- 

 tions which it appears to me of importance to rectify. The author 

 has stated (p. 144), " that the interposition of water between tho 

 j>ores and fissures of granulated ice contributes largely to develop in 

 them that beautiful blue colour which is so much admired.'* It is 

 long, indeed, since M. Agassiz has proved that blue ice contains more 

 water than white ice ; but the blue colour appears to me to be owing 

 rather to the absence of air than the presence of water, for the white 

 ice is infiltrated with water like the blue, but the white ice is wholly 

 filled with spherical bubbles of air. In the blue ice, these are re- 

 placed by water of infiltration. M. Celestin Nicollet has proved this 

 by direct measurement, shewing that 500 grammes of blue ice con- 

 tain only 0-5 cubic centimetres of air, while the same weight of white 

 ice contains 7*5 centimetre cubes ; accordingly, when wo look at a 

 fragment of ice half blue and white, wo see that the white part 

 is filled Nvilh bubbles of air, while the blue part is almost wholly 



