424 



ILLUSTRATIVE EXPERIMENTS 



over the cheek (Fig. 70). Now shift the point of percussion to a position 

 over the pharynx just behind the angle of the jaw and percuss again. Note 

 that the " cheek notes " rise as one passes from U A E I, while 

 the " pharynx notes " rise U A and fall to E and I. This demon- 

 strates the double nature of the mouth cavity in producing E and I. 



51. Prepare a series of bladders rilled completely with (a) air, (6) water 

 and (c) some viscous fluid like syrup and (d) lard. Percuss and palpate 

 each. 



52. Demonstration of the effect of colour on the absorption of radiant 

 energy (L. Hill). Two similar pieces of cotton tape, one white and the other 

 black, are suspended so that the end of each dips in a graduated cylinder 

 filled with water. Place first in the shade and measure the amount of 

 water evaporated from each cylinder during a period of 30 minutes. Refill 

 with water to the same level and repeat the experiment in direct sunlight. 



/ 



o?- 



08- 

 07 - 



06- 



04- 



02- 



0-9 



0-8 



07 



0-5 



0-2. 



0-1 



-log [H* ] or pH = x + . . . 



FlO. 84. Graph for Conversion of pH to C H - 



Graphic Conversion of S0rensen's pR( - log (H*)) into Concentrations of 

 Hydrogen Ions and the reverse (Roaf , Journ. of Physiol). Fig. 84 is a graph 



