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BOARD OF AGRICULTURE. [Pub. Doc 



of air is the most impure. The amount of carbonic acid in 

 different parts of the same stable is not the same. 



I may say that a difference of two parts in ten thousand 

 in a room, over the normal, is unpleasant to most of us ; 

 whilst the presence of five parts per ten thousand of car- 

 bonic acid in the air of a room, above the normal, renders 

 the place extremely offensive and oppressive to the senses. 



Ammonia is present in traces in the air of towns, but in 

 air vitiated by respiration it may be found in large amounts. 

 The ammonia itself is not injurious, but, as Dr. Smith ex- 

 presses it, " it has very bad relations, and keeps bad com- 

 pany ; " in other words, it is the product of organic matter, 

 and is regarded as another index of impurity. 



The following table will show the constitution of the air 

 in the twenty-five burns examined : — 



Average number of bacteria of barns with air good, 

 Average number of bacteria of barns with air fair, 

 Average number of bacteria of barns with air bad, 



376 

 397 

 473 



