The Determination of Organic Matter in Air. 243 



higher in the middle of the day, and higher still towards evening, 

 after which it decreases thus : — 





Night, 8 p.m.— 5 a.m. 





No. of 

 cases. 



Lowest. 



Highest. 



Mean. 



Organic matter (0 required per \ 



1,000,000 vols, of air) J 



Carbonic acid (per 10,000 vols. | 



9 

 9 



2 2 

 3-0 



6-7 

 5-6 



3- 9 



4- 1 





Morning 5 a.m. — 10 a.m. 





No. of 



cases. 



Lowest. 



Highest. 



Mean. 



Organic matter (O required per 1 



1,000,000 vols, of air) j 



Carbonic acid (per 10,000 vols. \ 



4 

 9 



3-2 

 1-8 



6-5 

 4-1 



4-9 

 2-9 





Mid-day 10 a.m. — 3 p.m. 





No. of 



cases. 



Lowest. 



Highest. 



Mean. 



Organic matter (O required per 1 



1,000,000 vols, of air) j 



Carbonic acid (per 10,000 vols. ^ 



12 



14 . 



1-6 

 2 2 



15-7 

 4-9 



7-9 

 3-4 





Evening 3 p.m. — 8 p.m. 





No. of 

 cases. 



Lowest. 



Highest. 



Mean. 



Organic matter (O required per 1 



1,000,000 vols, of air) [ 



Carbonic acid (per 10,000 vols. \ 



25 

 20 



2-6 

 1-9 



16-2 



5-3 



9'1 

 3-5 



