EXPERIMENTS 267 



c) Study similarly painful points and warm points, using a 

 heated point of pencil or wire for latter. 



4, a) Put finger of right hand into warm water and finger of 

 left hand into cold water. Note immediate sensations ; changes 

 in sensations after fingers have remained some time in water. 



b) Withdraw fingers and plunge both immediately into ves- 

 sel containing lukewarm water. Compare sensations of two 

 fingers. 



Taste and Smell 



Materials: Sugar; salt; dilute vinegar; quinine; dilute am- 

 monia, one drop of strong ammonia in glass of water ; cabbage ; 

 onion ; carrot. 



Experiments (2 students, one as blindfolded subject, other as 

 experimenter) : 



1) Dry tongue, and determine taste of dry sugar. Compare 

 with taste of moist sugar. Determine most sensitive part of 

 tongue. 



2) Test similarly with salt and other substances, closing nose 

 to avoid odor. 



3) Determine which have odor. 



4) Determine relative proportions of taste and odor. 



Hearing 



Materials: Tuning fork and its resonance chamber; violin 

 or stretched cat-gut; violin bow; [apparatus for manometric 

 flame] . 



1) Pluck violin string and note dependence of sound upon 

 vibration. 



2) Strike tuning fork and note dependence of volume upon 

 amplitude of vibrations of prongs. 



3) Place finger on middle of violin string, thus doubling rate 

 of vibration. Pluck string and compare pitch with that of 

 whole string. 



4) Strike tuning fork and hold prongs over its resonance 

 chamber. 



5) Test acuteness of hearing by determining how far off a 

 watch can be heard. 



6) Test accuracy of sense of direction as determined by hear- 



