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1

Pneumatics.

That Air in its natural State is necessaryfor Fire and Flame , is obvious from the st* i

den FxtinBion of a Candle , a live Coal, & c ’ iin the exhausted Receiver. Also Gunpowder ;fired therein will not take Flame, or be '

plostve, but melt and die away.

That the different Velocities with whi c ^heavy and light Bodies descend in the A^tis owing to the Air’s Resistance only, is m 9 "nifest from the equal Velocity or Swiftn e *with which all Bodies descend in thehausted Receiver , as is shewn in the Expertment with a Guinea and a Feather.

Air is likewise necessary for the Ex id'ence and Propagation of Sounds; for aBell placed under the Receiver, and run#*,will not be heard when the Air is dra^out; but in condensed Air, the Sound ^be augmented in Proportion to the Cot 1 "de nsation.

That Fermentation., PutrefaBion , & c *depend on the Air, and are promotedit, is shewn by preserving the Fruit in the 1 *”natural Bloom and Perfection through ^Winter in an exhausted Glass.

The Use of the Diving-Bell dependsthe Pressure and Spring of the Air : ^fince the Space which Air takes up is tefprocally as the Power compressing it, tlS

eviden (