154 VIBRATORY IMPULSES OF AIR. 



the upper side. On stopping the vibration of 

 the particles of steam by a jet of cold water, they 

 collapse, like the balls of electroscopes when the 

 excitation is withdrawn. A cubic foot of steam is 

 thus reduced to occupy the space of only one 

 cubic inch of condensed water, leaving the remain- 

 der of the space a vacuum. The cubic inch of 

 water, and the additional cold condensing water 

 with the air it contains, is extracted by the air- 

 pump of a condensing engine, while the vibrations 

 of particles of the- air continue to act against the 

 upper side of the piston with a resultant force of 

 fifteen pounds on each inch. 



The vibrating particles of air, put in motion by 

 the voice, impinge against the little disc or piston 

 of a phonograph, with sufficient force to indent a 

 sheet of tin-foil by every vibrating impulse. 



The particles of steam are put into similar vi- 

 bration by the excitation of heat in a furnace 

 beneath a boiler, with a force acting against the 

 inner sides of the boiler sufficiently to burst it. 



By intensifying the excitation of all organic sub- 

 stances by heat, the molecules of hydrogen, oxygen, 

 and nitrogen are made to vibrate to such an extent 

 as to be driven off, leaving the skeleton of all 

 organic formations in carbon, with the organic 

 structure complete, as manifest in wood charcoal. 



By increasing the intensity of vibrations of the 

 residuary charcoal, they excite by contact the 

 adjacent molecules of oxygen in the surrounding 



