100 M. Boussingault's Account of 



relieved from his uncomfortaljle sensations, when a gentle north- 

 east wind began to blow. In America, the meteorological con- 

 dition which attacks the respiratory organs so severely is termed 

 Soroche. In the language of the American miner, Soi-oche 

 means iron-pyrites, an indication that the cause of this pheno- 

 menon has been sought in subterranean exhalations. This is not 

 an impossible cause, but it is more natural to consider the so- 

 roche as an effect produced by the snow. 



The feeUngs of difficulty of breathing which I myself have seve- 

 ral times suffered on snow when the sun was shining on it, have 

 suggested the conjecture that an impure air is evolved by the ac- 

 tion of the heat of the sun on the snow. This singular idea was 

 confirmed by an old experiment mentioned by Saussure, according 

 to which he believed he had discovered that the air evolved from 

 the pores in the snow contained less oxygen than the atmo- 

 sphere. The air used for the examination was taken from the 

 pores of the snow collected on the Col du Geant. The analy- 

 sis was made by Sennebier, by means of nitrous oxide gas, 

 and compared with that of the air of Geneva. The results as 

 reported to us by Saussure were the following : — 



" In Geneva a mixture of equal portions of atmospheric air 

 and nitrous oxide gas yielded, on two trials, 1.00 residue. The 

 air from the snow yielded one time 1.85, and a second 1.86 re- 

 sidue. These trials, which seem to indicate great impurity of 

 the air, would require further experiments to ascertain the na- 

 ture of the gas which in this air occupied the place of the 

 oxygen." 



For a long time I had cherished the desire to repeat the ex- 

 periment of Sennebier ; for if it were actually true that the air 

 of mountain snow contains less oxygen than common air does, 

 we should be able to understand how the impure air evolved by 

 the action of the heat of the sun, by being dispersed through 

 the atmosphere, could ( ppress those persons who were obliged 

 to breathe it. With this view I filled a flask with snow at the 

 station of CMUapuUu. When we returned to the farm of Chim- 

 borazo, the snow was entirely melted, and the water so produced 

 occupied about an eighth of the flask ; a space of seven-eighths, 



* Saussure, Voyage dans les Alps, vol. vii. p. 47'-. 



