TENSION-EQUALIZER UNIT. 



31 



P- 



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. 



Fig. 8. — Apparatus used for tests of 

 respiration apparatus with burn- 

 ing ether. 



A, 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. 



^ee Part III. 



