METEOROLOGY AND ALLIED SUBJECTS. 265 



Tliis result j^oints directly to the aqueous vapor as the principal ab- 

 sorbin,u- substance, for tbe diminution of temperature of aqueous vapor 

 with tbe altitude is expressed bj- Hann's formula : 



0=6500 (log/o— log/) 

 ft 

 We can then conclude that the aqueous vapor is not the principal 



absorbing substance for the ultra-violet rays, for, if we compute a,])proxi- 



mately from the co-eflficients above given, we Hud the value of g for the 



absorption of the air g = 890.3, a value which coincides so closely with 



that derived from observations (868.2), that it proves the air to be the 



absorbing substance and not the vapor of water. {Z. 0. G. M., Voh XV, 



1880, p. 444 ) 



Mr. E. Z. Moss has examined the air of the arctic regions microscopi- 

 cally, and shows that although its dust contains organic cells, yet there 

 is every i)robability that these are not such as can give rise to mold, 

 putrefaction, and disease. He finds the amount of carbonic-acid gas 

 in the atmos]:)here of the arctic regions for three chemical determina- 

 tions to be 0.0042, 0.0483, and 0.0536, the average being 0.0553, which 

 is decidedly greater than in the lower latitudes. The amount of moist- 

 ure in the air was also determined by him by weighing. He found, for 

 instance, for a temperature — 54.8° F. and a pressure of 29.75 inches, 118.2 

 liters of air contained only 0.053 grams of water. {Z. 0. G. .1/., Vol. XV, 

 1880, p. 492.) 



Puisseux has found the following relative numbers for the actinometric 

 effect of solar rays as observed at different altitudes in the Alps with 

 the Arago-Davy conjugate thermometers: 



IMunter and Aubin have devised a new method of determining the 

 quantity of carbonic- acid gas in the air, and have made a series of reg- 

 ular observations in Paris and its neighborhood. They find the volume 

 to be from 2.88 to 4.22 i)arts of gas in 10,000 of air. The maxima occur 

 with cloudy sky and quiet weather; the minima occur with clear sky 

 and windy weather; the absolute maxima occurred durinf heavy snows 

 and dense fogs. {Z. 0. G. M., XVI, 1881, p. 54.) 



Armstrong has investigated the diurnal variations and the quantity 

 of carbonic-acid gas contained in the atmosphere from 27 mid-day and 

 29 mid-night observations, he finds during the day 2.9603 volumes of 

 carbonic-acid gas, but dariug the night 3.299 volumes in 10,000 volumes 



