346 VETERINARY STATE BOARD 



Define proximate principle. Name three proximate principles and 

 mention a common food substance in which each is re- 

 spectively contained. 



A proximate principle is a substance which is capable of being 

 decomposed into simpler principles or parts, as distinguished from 

 ultimate principles which, are not capable of further division. For 

 example, NaCl is a proximate principle and can be decomposed 

 into Na and CI, which, as ultimate principles, cannot be further 

 subdivided. 



Starch, protein, and fat are proximate principles which may be 

 decomposed into C, 0, H, etc. A common food substance which 

 contains these principles is oats. 



Air and Ventilation 



What is the average composition of (a) atmospheric air, (b) air that 

 has been breathed ? 



(a) Oxygen, 20.96; nitrogen, 79.01; carbon dioxide, 0.03. 



(b) Oxygen, 16.02 ; nitrogen, 79.01 ; carbon dioxide, 4.38. 



At what stage of chemical impurity does rebreathed air cause oppres- 

 sion and at what stage does it become irrespirable? 

 Air becomes oppressive when it contains only 11 per cent, 

 of oxygen, and irrespirable when the oxygen falls to 3 per cent. 



State the minimum amount of air space that should be provided in a 

 stable (a) for each horse, (b) for each cow. 



This all depends on how often the air of the space is changed. 

 A horse requires 15,000 cubic feet per hour, and cattle slightly less. 

 The average air space given to a horse is 1500 cubic feet, and to a 

 cow 1200 cubic feet. In the case of the horse, the air would need 

 to be changed ten times per hour, and for the cow about twelve 

 times. 



Does air space greatly in excess of the required amount render the ven- 

 tilation of a stable unnecessary? Give reason for your 

 answer. 



No. The larger the air space, the smaller number of times the 

 air of that space needs to be changed; but once the impurities are 

 present, they remain and will only be removed by supplying fresh 

 air. 



Describe the King system of ventilation. 



Fresh air enters through openings in the outside wall, three or 

 four feet below the ceiling, passes up between the outside and the 



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