No. 4.] STABLE MANAGEMENT. 183 



have previously mentioned that it has been condensed and 

 collected from the air ; it may also be drawn through dis- 

 tilled water by means of an aspirator, and its presence 

 detected on analysis. Angus Smith found that it condensed 

 from a crowded room. If organic matter derived from the 

 skin and lungs of human beings possesses such objection- 

 aide properties, what must the organic matter from the 

 habitations of animals possess, when we consider that not 

 only are the skin and lungs acting but that we have depos- 

 ited in the place where they live the discharges from the 

 bowels and kidneys? 



When organic matter is produced, it rapidly adheres to the 

 walls, woodwork, etc., and there, parting with its water, it 

 becomes fixed, forming a greasy coating. This is the reason 

 why the peculiar penetrating odor in badly ventilated stables 

 is so difficult to remove, even with free perflation of air ; it 

 hangs to woodwork, walls and ceiling, and is readily experi- 

 enced on entering a building of this description. 



This organic substance, owing to the moisture in the air, 

 is constantly undergoing change, giving out carbonic acid, 

 ammonia and sulphuretted hydrogen. From observations 

 made by Dr. de Chaumont and others, it has been shown 

 that the organic matter in the air of buildings is in proportion 

 to the carbonic acid of respiration. This is a most important 

 point, for it affords us a ready index to the purity of the 

 air, by determining the amount of carbonic acid present in 

 it. It must be distinctly repeated, as we shall have later 

 on again to note, that it is not the actual presence of a large 

 amount of carbonic acid in the air which is to be dreaded, 

 but the certain indication which this affords of the large 

 amount of organic matter which is present. This brings 

 us to a consideration of the carbonic acid present in the air 

 as the result of respiration. 



In a stable where ridge ventilation or an outlet in the 

 roof exists, the upper stratum of air is the purest ; the 

 stratum next the ground is very impure, though, owing to 

 the presence of ammonia, this is not apparent. In collect- 

 ing, therefore, stable air for analytical purposes, it should 

 never be taken nearer than six feet from the ground. In 

 stables where no outlet exists in the roof, the upper stratum 



