May, 1929] SIMPLIFIED TECHNIQUE FOR MEASURING ENERGY 



15 



windchest and forces it in turn through the driers, absorbers for CO2, and 

 meters, all of which are connected in series. The air not passed through 

 the absorbers leaves the windchest through a free opening on top and is 

 carried off through a room ventilating hood above the table. The object 

 of using only a fractional part of the total ventilating current is to reduce 

 the size of the absorbers so that they may be conveniently handled 



Figure 5 — Schematic outline of apparatus for ventilating respiration chamber and for analy- 

 sis of aliqtiot sample of air coming from chamber 



C, respiration chamber; B, blower for removal of air from chamber; c, cover in water 

 seal of blower container; W, windchest; d, opening for free discharge of air into labora- 

 tory room; s, can with rubber cap expansion top attached to circuit breaker r, which 

 actuates magnetic bypass e thus automatically maintaining control of aUquot air sample 

 from windchest W; b, hand-controUed bypass to aUquot air sample; P, manometer to 

 indicate the air pressure in sampling can; Gi, sulphuric acid to remove moisture from air 

 stream; E, airpump; G2 serves as check to Gi to indicate approach of saturation; \i and 

 \-2, valves to deflect air stream from one set of carbon dioxide absorbers (Si and So) to the 

 other (Li and L2); Ai and A2, sulphuric acid to retain moisture absorbed from soda lime 

 in Si and S2; Di and D2, sulphuric acid to retain moisture absorbed from Li and L2; Pi 

 and P2 petcocks to tap air stream for sampling; t, barium hydroxide to test air stream 

 for loss of carbon dioxide; K, sodium bicarbonate to absorb fumes; Mi and M2, meters. 



and, secondarily, to economize on absorbent materials and on labor. The 

 size of the aliquot relative to total ventilation may be varied from 4 to 50 

 per cent by altering the size of the free opening for waste. The principle 

 of the aliquoting mechanism has been repeatedly described.^ 



1 Benedict, F. G., W. E. Collins, M. F. Hendry, and A. Johnson, New Hampshire 

 Agric. Expt. Station Technical Bulletin No. 16, 1920; Benedict, F. G., and E. G. Ritzman, 

 Carnegie Inst. Wash. Pub. No. :324, 1923, pp. 61 et seq.; ibid., Carnegie Inst. Wash. 

 Pub. No. ;377, 1927, pp. 29 et seq. 



