1879.] Various Altitudes on the Island and Peak of Tenerife. 513 



boards) corresponded to 1*20 litre of air, while with, the guide 

 1 grm. of carbonic acid corresponded to 1*48 litre. 



As the mean results obtained for the amount of carbonic acid 

 expired sitting and while on the tread-boards, agrees so well with 

 both of us respectively, I have thought it worth while to calculate 

 the mechanical power developed by the combustion of the amount of 

 carbon burnt while working the tread- boards, in excess of that con- 

 sumed in the sitting posture. 17*92 kilos, were raised to a height of 

 128*5 millims., 45 times per minute. 



Per 100 kilos. 



Mean carbonic acid per minute on the tread-board 1 "435 

 „ „ sitting 0*676 



Excess „ expired on the tread-boards '759 grm. 



Corresponding to 103*6 kilogramme t res (0*1285x17*92x45 = 103*6) 

 of work done, or 0*00733 (103*6 : 0*759 = 1 : X ) C0 2 expired, was 

 equal to an oxidation of 0*002 grm. carbon, capable of raising 1 kilo, 

 to 1 metre. 



From Watts' Dictionary of Chemistry (vol. iii, pp. 105 and 129) 

 the mechanical action of one unit of heat=423*5 gramme-metres, 

 and one gramme of carbon yields by its combustion 8080 units of heat. 

 Therefore, 1000 grammes carbon = 8080000 units of heat yielding 

 (8080000x423*5) 3421880000 gramme-metres or 3421880 kilogram- 

 metres for the mechanical action of 1 kilogramme of carbon. 



The relation between the above theoretical mechanical power of 

 burning carbon and the actual mechanical power found to be evolved 

 in my experiments was as follows : — 



1000 grms. : 3421880=0*002 : x. x =6*84. 



Therefore we only applied -J—, or 0*147 of the power the carbon 



6*84 



we burnt on the tread-boards (in excess of that consumed sitting) 

 was theoretically able to exert.* 



As to the percentage of the carbonic acid in the air expired, while 

 on the tread-boards, it increases at the highest station in my case, and 

 this increase is somewhat gradual from the lowest to the highest 

 station. With the guide the maximum percentage is met with at the 

 middle station. 



The frequency of the respiration increased in my case from the 

 lowest to the highest station, while with the guide it is slightly in- 



* There is so little carbonic acid present in the atmosphere, especially at some 

 altitude above the sea (M. P. Truchot, " Compt. Rend, de l'Academie," vol. lxxvii, 

 1873) , that its presence in the air breathed has not been taken into account in this 

 calculation. 



