BANDELIER — ON OZONE. 



417 



Observations of Ozone, made in Highland, Madison Co., 

 Ills. By Ad. F. Bandelier. 



Having made regular observations of ozone with the 

 usual ozone-papers and the colored scale of Professor Schon- 

 bein, I present herewith to the Academy the result of my 

 observations for the year 1865. They were made twice in 

 24 hours, from 7 in the morning to 7 in the evening, and 

 from 7 in the evening to 7 in the morning, to show the dif- 

 ference of ozone during day-time and night. 



1835. 



MEAN OF MONTH. 

 DAY. NIGHT. 



January 3.2 5.0 



February 2.6 4.1 



March 3.1 4.7 



April 4.3 5.1 



May 4.6 4.2 



June 4.8 3.3 



July 5.0 3.3 



August 5.4 3.2 



September 5.9 1.5 



October 3.0 3.5 



November 2.9 3.3 



December 2.0 3.5 



Mean 3.9 3.7 



Calculated from the daily observations (621), the mean 

 of all the observations in day-time is 3.87, of those in the 

 night 3.64, and the mean of the whole year 3.75. The year- 

 ly mean of the observations made in day-time is therefore 

 0.23 greater than that of the night observations. But this 

 difference is still greater in different months : while Janu- 

 ar} r , Febi'uary, March, April, October, November, and De- 

 cember, give as 



Mean of day observations 3 05, and for the night 4.14; 



the months of May, June, July, August, and September, 

 show as 



Mean of day observations 5.14, and for the night 3.10. 

 The first group consists, with the exception of April, of 

 those months in which the days are shortest; and the sec- 

 ond group, of those with longest da} 7 light. The shorter or 

 longer daylight seems, therefore, to act an important part 

 in the formation of ozone. The quantity of ozone in day 

 and night time is in the first group as 1 in day to 1.39 in 

 night; and in the second group, as 1 to 0.60. 



The formation of ozone seems to be affected, also, by at- 

 mospheric humidity. Great humidity is generally accom- 

 panied by a considerable quantity of ozone. In continued 

 dry weather the ozone-paper is hardly colored. 



The highest point in the scale, No. 10, was reached bu 



