190 Scientific Proceedings, Royal Dublin Society. 
Morley, at Cleveland, U.S.A., and Kreusler, at Bonn, collected and 
analysed their own samples by two different methods, namely, 
explosion with hydrogen (Morley), and ignition with copper 
(Kreusler). Air samples from Tromso in Norway, and from Para 
in Brazil, were collected by local scientific men and sent to Hempel, 
at Dresden, for analysis, in sealed tubes, where he also collected 
samples. All of these he analysed by absorption with caustic 
potash and pyrogallic acid. Unfortunately, he did not attempt 
to determine the carbonic anhydride separately, but contented 
himself with determinations of its joint amount with oxygen, 
from which he deducted 0°03 per cent. in all cases, to arrive at 
the percentage of oxygen. 
In the subjoined table, we give the mean figures appearing in 
Hempel’s memoir,' but the maxima and minima and the resulting 
variations we have ourselves collected from the figures, as they 
are not specifically stated in his summary :— 
Percentage amount of 
Latitude. Locality. eee sel ioe say 
Mean. | Maxm.} Minm. 
| Z 
69°40’ N. Tromsé (Norway), . | Hempel, 20°92 | 20°97 | 20°87 | 0-10 
61 30 N. Dresden (Saxony), 6 50 20°90 | 20°93 | 20°85 | 0-08 
50 50 N. Bonn (on the Rhine), .| Kreusler, | 20-92 | 20-94 | 20-90} 0:04 
41 27 N. Cleveland (United States) | Morley, 20°98 | 20°95 | 20°90 | 0-05 
1 27 S. Para (Brazil), . . | Hempel, | 20°89 | 20-96 | 20:83 | 0-13 
We may therefore assume that the total variation is about. 
0-08 per cent. (mean of the above variations), or probably about 
eight times that of the atmospheric carbonic anhydride. 
Kreusler gives the following table, indicating seasonal varia- 
t10n8 :-— 
January, . : . 20-910 pully é ~ 20:98 
February, : 5 MMe lal August, . : . 20-920 
March, . fi oo September, . 5 Adwile 
Alora, : - 20-910 October, . : 205909 
May, ‘ : 5 ANOILO November, . . 20:905 
June; 5 a 20-907, December, : . 20°906 
1 Hempel, ‘‘ Berichte d. deutsch. chem. Ges.,’’ 20 [1887], p. 1864. 
