636 



SCIENCE 



[N. S. Vol. XLI. No. 1061 



spaced at the ceiling of the room, and after 

 being passed through an air washer, where 

 it was cooled by the water about 15 degrees, 

 it was returned to the room. The volume of 

 air thus recirculated averaged 8.9 cubic feet 

 per minute per pupil. 



The results obtained in this room were 

 compared with results in a room in the 

 Adams School, the pupils in both rooms 

 being of the same age, grade and general 

 condition. The room in the Adams School 

 was ventilated as is usual in the case of 

 schoolrooms. The air was admitted 

 through one opening above the blackboard 

 and was exhausted through one opening 

 near the floor on the same side of the room. 

 The air was not washed and the volumes 

 averaged 35.4 cubic feet per minute per 

 pupil. The temperature averaged slightly 

 lower and humidity slightly higher in the 

 Jackson schoolroom. 



The carbon dioxide averaged 12.5 parts 

 per 10,000 in the Jackson School and 9.1 

 parts per 10,000 in the Adams School. 



bust counts showed 105,000 particles per 

 cubic foot of air in the Jackson School and 

 225,000 in the Adams School. As a result 

 of these experiments, covering a period of 

 four months the conclusion is offered that 



it is impossible to demonstrate physical or mental 

 deterioration due to the use of reeireulated air. 

 Neither is it possible to ascribe any discomfort on 

 the part of the pupils or the teacher to this re- 

 circulated air. 



The air washing, it is stated, was not 

 sufficient to remove all odors, but they were 

 reduced to such an extent that they were 

 not offensive to persons occupying the room 

 continuously, although noticed by persons 

 entering the room. 



In this experiment the problem of the 

 use of recirculated air was combined with 

 that of the use of a reduced volume of air 

 delivered directly toward the face of the 

 pupil. The two problems should be sepa- 

 rately studied. More light on the effect of 



recirculated air is desirable, as is the case 

 with reduced volumes of air directly de- 

 livered and generally distributed. 



In the case of one of these experiments 

 the volume of air used was more than ten 

 times that customarily used for ventilating 

 purposes, and in the other case the volume 

 of air used was less than one third that 

 ordinarily used. Experiments with the 

 standard and other volumes of air with the 

 standard and diffused methods of intro- 

 duction are desirable. 



Studies along these lines are planned by 

 the Ventilation Commission in connection 

 with its experimental plant in Public 

 School No. 51, the Bronx, New York City. 



The economy of air recirculation was pre- 

 sented by the writer in the Am. Physical 

 Education Review of December, 1913. Very 

 marked economy was credited to recircula- 

 tion. This claim was disputed by Evans 

 in the June issue of the Heating and 

 Ventilating Magazine, the claim being 

 made that the cost of fresh cold water re- 

 quired for cooling and dehumidifying the 

 recirculated air offset the saving in heat. 

 Actual experience proves that such is not 

 the case. Professor Bass states that water 

 cost three cents per day during his experi- 

 ments, which is vastly less than the amount 

 stated by Evans. Dr. McCurdy states that 

 some water was used for cooling, but even 

 with 40,000 cubic feet of air per minute 

 recirculated the cost of the fresh water 

 used does not appear to have been a seri- 

 ous item. 



It is manifest that a large amount of heat 

 is saved, and this certainly warrants the 

 most careful study of the problem of recir- 

 culation. Should it prove in every way 

 satisfactory a great step in advance will 

 have been made in the field of mechanical 

 ventilation. But it may not be recom- 

 mended as yet. D. D. Kimball, 

 Member of New York State 

 Commission on Ventilation 



