History of Air-Analysis 



51 



Average results for February, March, April, and May (with rainfall) 

 were for oxygen, 20.717 per cent, and for carbon dioxide, 0.033 per cent. 

 For June, July, and August (without rainfall) the average results were for 

 oxygen, 20.920 per cent, and for carbon dioxide, 0.039 per cent. 



Macagno emphasizes the low percentage of oxygen found during the 

 sirocco wind, the extremely low percentages on March 20 and May 31 

 being due to this cause. The percentages of oxygen obtained during the 

 sirocco were as follows: 



1879. per cent 



March 20 19.994 



March 21 20.008 



March 22 20.064 



April 15 19.998 



1879. 



per cent 



May 29 20.021 



May 30 20.032 



May 31 20.017 



Commenting on these results, Macagno writes: 



Here we have seven determinations of the most important element of air during that 

 singular wind with its heat and dryness, 1 rendering so troublesome the medium in which 

 we are always bathed, and in all cases the want of oxygen is very evident. 



Simultaneously, but independently of von Jolly, E. W. Morley, 2 of 

 Cleveland, engaged in the accurate analysis of air with a view to study- 

 ing the variations in composition and formulating a hypothesis which he 

 hoped would be subsequently verified with an improved apparatus. 

 Morley maintained that the descent of cold air from higher regions brought 

 with it air poorer in oxygen, presupposing the correctness of the Dalton 

 hypothesis. The apparatus 3 used was a modification of that of Frank- 



Table 35. Determinations of oxygen in atmospheric air collected by Morley after sudden 



depressions of temperature. 



1 During the sirocco wind the relative humidity of air (determined by the psychrom- 

 eter) is diminished to 30, 24, 20, and even 18. 



2 Morley, American Journal of Science and Arts, 1879, 18, p. 168. 



3 Morley, loc. cit.; also Amer. Chem. Journ., 1881, 3, p. 1. 



