170 



POULTRY CULTURE 



0.2 per thousand added to the already 0.4 normally existing 

 in the air. It has been determined that the greatest amount 

 of carbonic acid that can exist in the air without impairing 

 the "freshness" is 0.2 per thousand. If the air smells rather 

 close of respiratory impurities it is 0.4 per thousand. If the 

 air is close then the impurities are recorded as 0.6 per thousand. 

 If very close, that is, offensive, the carbonic acid present 4s 



Fig. 61. — A small open front colony house. Plenty of fresh air is essential 

 in successful poultry culture. 



recorded as 0.9 per thousand. The smell cannot differentiate 

 beyond this degree. 



A poultry house should be ventilated so that it will not have 

 more than 0.2 per thousand. One difficulty in carrying out 

 this test is the odor of ammonia and other products originating 

 from the droppings. 



Fresh air may be supplied in two ways — namely: 



1. The process of diffusion. 



