144 Report of the Besearches of M, Agassiz. 



cealed until the fit occasion presents itself. Amongst the numerous 

 administrations of the same wise and merciful design, it is not unreason- 

 able to believe that the completion of navigable channels across the isth- 

 muses of Suez and Darien are enterprizes amongst the events designed 

 to minister to the growing wants and improvement of the human race. 



JReport of the Besearches of M. Agassiz during his last two so- 

 journs at r Hotel-des-Neuchatelois, upon the Lower Glacier 

 of the Aar, in the years 1841 and 1842. By M. E. Desor. 



(Concluded from Vol. xxxv., p. 313.) 



Observations upon the Composition of Ice. — Observations 

 upon the composition of ice had been demanded from all 

 quarters, on account of the intrinsic importance of this sub- 

 ject, and on account of the very contradictory opinions which 

 had been published regarding it. Accordingly, when we re- 

 turned to the glacier of the Aar, in the year 1842, we took 

 along with us a complete armamentarium of tubes, probes, 

 weights, balances, and other apparatus of this kind ; and M. 

 Nicolet, in concert with M. Vogt, undertook the conduct of 

 these observations. A kind of laboratory was constructed 

 for the purpose, near our hut, to the north of it ; and the 

 day after our arrival M. Nicolet commenced operations.* 



From the observations so made, it follows that the blue ice 

 really contains the smallest quantity of air. It is true that 

 the ice taken from the Gallery did not contain much more ; 

 but it ought to be remembered that there the entire mass 

 of the glacier is as it were transformed into blue ice. Lastly, 

 the white ice, which owes its dull appearance to the numerous 

 air-bubbles it encloses, contains much more air than the blue 

 ice. M. Hugi, as may be known to many of our readers, 

 had previously discovered that, when ice is put into an enclosed 

 bell-jar, supplied with a tube which is plunged into a mercu- 

 rial trough, the mercury ascends in the tube during the course 

 of the night, and descends again during the day ; and from 



• For an account of these Experiments, see Jameson's Journal, vol. xxxiii., 

 p. 401. 



