342 



Dr. W. Marcet. A Chemical Inquiry [June 20, 



Litres of air expired 

 for 1 gram C0 2 , 

 reduced to 0° and 

 760 mm. 



Mean before and 

 after ascent. 



Courmayeur 1202 m. (3,945 ft.) .... 14 35 



Summit Col du Geant . . . 3362 „ (11,030 „).... 13'5 



On M. David, aged 25. 



Near Geneva 375 m. (1,230 ft,).... 13 7 



Mean before and 



9.f"fc(~ , I* 9SC6Ht 



Courmayeur 1202 „ (3,945 „).... 14 8* 



Summit Col da Geant . . 3362 „ (11,030 „).... 12'6 



The experiments were made by determining as carefully as possible 

 the volume of air expired within a given time, and then estimating 

 the amount of carbonic acid it contained by means of Pettenkofer's 

 method. The volume of air, reduced to 0° C. and 760 mm. pressure, 

 holding 1 gram of carbonic acid, was then easily calculated. 



These experiments were subsequently repeated in 1882 on the 

 Rigi Mountain in Switzerland, altitude 1594 metres (5230 feet), 

 and as the results obtained have never been published, beyond a 

 short reference to them in a communication to the Alpine Club, 

 they are included in the present paper. My companion, Mr. Thury, 

 a young engineer, aged twenty-five, submitted to the inquiry. 

 Fifteen experiments were made near Geneva at a mean barometer 

 pressure of 728 mm., and a mean temperature of 15*9° C, and 

 eighteen as soon afterwards as possible on the Rigi Staffel, at a mean 

 pressure of 639 mm., and a mean temperature of 7' 6° C. As might 

 have been expected, more C0 2 was exhaled in a given time on the cold 

 mountain station than in the Valley of Geneva, a mean of 0"350 gram 

 being expired near Geneva and 0*445 gram at the higher station, 

 giving an excess of no less than 21 per cent, of carbonic acid for the 

 Rigi. The amount of air expired — say breathed — for the expiration 

 of 1 gram C0 2 , reduced to 0° and 760 mm., was 10' 78 litres in the 

 Valley and only 9 '45 on the Rigi. Therefore, for a mean difference 

 of 89 mm. of atmospheric pressure, and with a marked fall of tem- 

 perature, less air by 12 per cent, was breathed on the mountain to 

 supply the oxygen required by the body to burn the same amount of 

 carbon as in the valley. 



The present investigation has been carried out in a laboratory of 

 the Physiological Department at University College, which Professor 

 Schafer has kindly placed at my disposal. Its object was to ascertain 



* This is an exceptional case, owing clearly to the small increase of altitude 

 between Geneva and Courmayeur, which only amounts to 827 metres. 



