406 Journal of Agricultural Research voi.xx, no. 6 



Building Ventilation. 1 In this report are given the results of analyses of air 

 samples taken at various points in five different barns. Mr. Clarkson 

 has called our attention to the fact that although the amounts of carbon 

 dioxid per 10,000 parts of air are correctly expressed in the tables, the 

 conversions to percentages are erroneous, because of misplaced decimal 

 points, and the percentage values should accordingly.be multiplied by 10. 

 The results published in this report show that in the five barns exam- 

 ined, which were presumably of reasonably modern construction, the 

 carbon-dioxid content of the air might be as high as 1.231 per cent, but 

 for the most part was not higher than 0.2 to 0.3 per cent. 



The dairy barn at Durham is admirably lighted and is, so far as one 

 can judge by the senses at least, well ventilated. The stock room is 

 approximately 100 feet long, 35 feet wide, and 8 feet 8 inches high, is 

 provided with windows on both sides, and has a concrete floor. The 

 ventilating ducts withdraw the air from near the floor, and outdoor air 

 can blow in on either side through screened openings. Practical experi- 

 ence indicates that this barn is admirably adapted for maintaining stock 

 in good health with a negligible amount of disease. 



Our study of the air in this barn did not include an examination of the 

 ventilation conditions, so far as draft, temperature, and psychrometric 

 measurements are concerned, but consisted solely of gas analysis made 

 in connection with the possibility of leakage of barn air into the respi- 

 ration chamber. To study the carbon-dioxid content of the air in a mod- 

 ern, well-ventilated dairy barn seemed a justifiable procedure. Being 

 unfamiliar at the time of our tests with the earlier series of observa- 

 tions cited above, we were astonished at our first results, which showed 

 on the average an amount of carbon dioxid in the barn air not far from 

 8 to 10 times the normal carbon-dioxid content of outdoor air. The 

 analyses were all made with the small Haldane gas analysis apparatus 2 

 by both authors at different times and after many years' experience 

 with the use of this type of apparatus. 3 



To obtain a general picture of the distribution of the carbon dioxid 

 in the air, samples were taken at different parts of the barn, but unfor- 

 tunately not simultaneously. Four samples were taken at 8.50 a. m., 

 four at 10.05 a - m -i f° ur at 11 a. m., and three at 11.40 a. m., all in 

 different locations. Subsequently the samples were taken at three 

 positions only, but variations in the time of day were studied under 

 these conditions. 



Approximately 40 milch cows were in the barn at the time. Of the 

 15 different positions at which air samples were taken, locations 1 to 5 

 were in the feed alley between the two rows of stalls and therefore in 



1 Clarkson, W. B., Smith, L. J., and Ives, F. W. [report of the] committee on farm building ven- 

 tilation. In Trans. Amer. Soc. Agr. Engin. Rpt. 12th Ann. Meeting, 1918, p. 282-306, illus. 1919- 



2 Haldane, J. S. methods of air analysis, ed. 2, p. 68. London, 1918. 



3 Special mention should be made here of the intelligent cooperation in our work of the dairyman, Mr. 

 Mario Quaregno, who collected samples for us at night with the greatest fidelity. 



