THE VITAL PROCESSES 



Carbon 



then insert a burning splinter in the tumbler. Account for the result. 

 Inference as to the weight of carbon dioxide. 



(e) Review experiments (page 101) showing 

 the presence of carbon dioxide in the breath. 



To illustrate the General Movement of Oxygen 

 through the Body. Into a glass tube, six inches 

 in length and open at both ends, place several 

 small lumps of charcoal (Fig. 59). Fit into one 

 end of this tube, by means of a stopper, a smaller 

 glass tube which is bent at right angles and which 

 FIG 59 Simple is made to ^ >ass throu h a close-fitting stopper to 

 apparatus for illus- ^ e bottom of a small bottle. Another small 

 is fitted into a second hole in this stopper, 



trating passage of oxy- 

 gen through the body. but terminating near the top of the bottle, and to 

 this is connected a rubber tube about eighteen 

 inches in length. The arrangement is now such that by sucking air 

 from the top of the bottle, it is made to enter at the distant end of the 

 tube containing the charcoal. After filling the bottle one third full 

 of limewater, heat the tube containing the charcoal until it begins to 

 glow. Then suck the air through the apparatus (as in smoking, without 

 drawing it into the lungs), observing what happens both in the tube 

 and in the bottle. What are the proofs that the oxygen, in passing 

 through the tube, unites with the carbon, forms carbon dioxide, and 

 liberates energy? Compare the changes which the oxygen undergoes 

 while passing through the tube with the changes which it undergoes in 

 passing through the body. 



