TENSION-EQUALIZER UNIT. 



31 



time the experiment begins until it is completed, is considered to be the 

 actual amount used by the subject, provided there have been no 

 changes in temperature or barometric pressure. A discussion of the 

 whole question of the determination of the oxygen consumption with 

 the unit respiration apparatus will be included in the discussion of the 

 results obtained with it. 1 



Check tests of the respiration apparatus. In the development of the 

 respiration apparatus, it was thoroughly tested by experiments in 

 which small quantities of ethyl ether were 

 burned. For this purpose a combustion 

 chamber of special construction was in- 

 serted in the ventilating air-pipe at the 

 point where the three-way valve is ordi- 

 narily attached. This apparatus, which 

 is shown in figure 8, consists of a large 

 metal tee, A, of the standard 2-inch size 

 (5 cm. internal diameter). Into this is 

 fastened an upright piece of pipe which is 

 surrounded by a tin water-jacket, J. On 

 the top an elbow is attached, into which 

 a pipe, C, is screwed. To the bottom 

 of the tee, A, is attached a short piece 

 of pipe closed with a rubber stopper. 

 Through this is passed, first, a brass tube 

 connecting with the rubber tube, B, 

 through which the ventilating current of 

 air passes; second, a small brass pipe to 

 which is attached a burner; and finally, 

 two electric wires, F and F'. Ether is 

 supplied from a glass vessel, G, which is, 

 as a matter of fact, an ordinary so-called 

 sulphur-dioxide condensing tube. A cur- 

 rent of air entering the ether tube at H 

 passes over the ether and becomes satu- 

 rated with ether-vapor. It enters the 

 combustion chamber, and issues from 

 the jet on the acetylene gas-burner, D. The vapor is ignited by 

 causing a high-tension spark to jump across the wires F, F', by 

 means of a spark coil. The heat developed from the combustion 

 is absorbed readily by the water in the water-jacket. In order to have 

 a constant flame, a steady air pressure must be maintained. This was 

 secured by inserting a tee tube between the rotary blower and the first 

 Wolff bottle. A small supply of air taken from this point carries the 

 ether- vapor into the combustion chamber. 



H 



FIG. 8. Apparatus used for tests of 

 respiration apparatus with burn- 

 ing ether. 



^4, combustion chamber; B, ingo- 

 ing ventilating air-current ; C, outgo- 

 ing air-current; D, burner; E, glass 

 window; F, F' , high-tension spark- 

 ing-current lead wires; G, container 

 for ether; H, supply of air under 

 pressure; /, water-cooler. 



'See Part III. 



