277 



The two last, in conducting the note, greatly lessened the intensity, 

 much more so than the substances described above. 



The muscular substance of the heart lowered the pitch. Skin 

 and cellular tissue, on the contrary, raised it. 



LIQUIDS. 



A large foot-pan was filled with water, and the vibrating fork was 

 partly introduced into this, but as no sound could be heard in this 

 manner without some resounding body, a small circular piece of wood 

 was used for this purpose ; the fork placed on this was first listened 

 to ; the fork with the piece of wood was then placed under the water ; 

 one ear was then immersed in the water, and the note so taken ; the 

 pitch was then found to be most decidedly heightened. Any objections 

 to this method of performing the experiment were obviated by the 

 following extension of it. The eyes being firmly shut, any variation 

 in the position of the fork, that is to say, whether it was moved closer 

 to or further from the ear, was accurately determined by the alteration 

 in the pitch. 



Next, a glass tube 29 inches long, with a diameter of -f ths of an 

 inch, was closed at one end, with a diaphragm of gutta percha, oil- 

 silk, or bladder (the same diaphragm being used in each set of com- 

 parative experiments). The tube was then filled with the fluid to be 

 examined. The ear being applied to the diaphragm, the stem of the 

 vibrating fork was introduced above into the fluid, care being taken 

 that neither the finger nor the fork was in contact with the glass. Ex- 

 periments conducted in the above manner gave the following results. 



* Water raised the pitch most appreciably. 



* Alcohol still higher. 

 Ether higher. 



A solution of protocarbonate of soda of the same specific gravity 

 as the blood, raised the pitch more than pure water. 



* A saturated solution raised it still higher. 



* Sulphate of baryta, suspended in water, raised it higher than any 

 other tried fluid. 



Prussian blue, suspended in water, raised it more than water, but 

 less than the sulphate of baryta. 



From the above results it appears that simple fluids heighten the 

 pitch in proportion to their diminished specific gravity, and that the 



