an Attempt to ascend Chimborazo. 101 



therefore, was filled with air which was chiefly derived from the 

 snow. I say chiefly, because a considerable portion of atmo- 

 spheric air must have entered during the filling of the flask 

 with snow. 



I decomposed the air from the snow of Chillapullu very care- 

 fully, by means of a phosphorus eudiometer. 



Eighty-two parts of the snow air left a residue of sixty-eight 

 parts nitrogen. Fourteen parts oxygen were therefore absorbed, 

 and consequently the air contained 0.17 oxygen. 



When we consider that the flask must, besides the air of the 

 snow, have also contained atmospheric air, we are inclined to re- 

 gard this analysis as a confirmation of the results obtained by 

 Saussure ; and the difficulty of the breathing on the glaciers on 

 which the sun is shining, the soroche of the high mountains of 

 Peru, would be to a certain extent explained, if we admit that 

 the air surrounding a glacier is in the immediate vicinity of 

 that glacier less pure than that of the atmosphere. 



The eudiometrical result which I obtained is doubtless free 

 from objections, but nevertheless further experiments are neces- 

 sary to prove distinctly that the air which I analyzed w r as exactly 

 the same as that obtained from the pores of the melted snow. 

 In fact, in order to procure this air, it was necessary for me to 

 wait for the melting of the snow. The air in the flask was 

 therefore in contact with that water containing more or less air, 

 which resulted from the melting. But it is known that, under 

 such circumstances, the water absorbs more oxygen than nitro- 

 gen, and that consequently the air with which the water is satu- 

 rated always contains more oxygen than atmospheric air does. 

 The air which remained in the flask, and which was that exa- 

 mined by me, might therefore contain less oxygen, notwith- 

 standing that, in fact, the air contained in the snow might have 

 the usual composition. This is the objection which, in strict- 

 ness, may be made to my result. In order to judge of Saussure's 

 result, it would, above all, be necessary to know what method 

 that celebrated traveller pursued, in order to obtain from the 

 snow the air examined by Sennebier. 



The philosophers who have visited high mountains, agree in 

 stating that the blue colour of the sky appears darker the greater 

 the height attained. On Mont Blanc, Saussure saw the sky 



