166

P N E UMATIC S.'

(4.) By raising up the Skin of the J&jjj(after the Yolk is taken away, and one h a ^

M

Smoke or Vapour. Hence, by the way, we so e ,|jReason why, when the Air grows lighter, it letsthe Vapours, and the Weather becomes misty, ^and wet or rainy.

EXPERIMENT XXXIV. ~

34. The Thirty-fiurth Experiment /hews the

of Gunpowder is owing to the Air. For if it be kiu ^in Vacuo , the Air, that so suddenly expands itself ‘ r oI ,the Powder, and gives such a Shock to the cost 111 ^Air, now finds none to encounter, and so makes ^sensible Appe ranee, otherwise than by the sinksoothe Mercury a little in the Gage by its Spring.

EXPERIMENT XXXV. y. s

35. The Thirty-fifth Experiment Jhews how \fi

are produced by refracted Light. Thus if a Cane 16 Jheld on one Side of the Receiver, and the Eye P

at some Distance on the other, as soon as the Ah e ,gins to be exhausted, and becomes attenuated and ^pletedwith Vapours to a proper Degree, the Ins, ^the Candle will be refracted through that Mediutd ^Circles of various Colours, very much resembling tseen about the Moon in a hazy Air at Night.

EXPERIMENT XXXVI. ^

36. The Thirty-fixth Experiment Jhews how theL ^of an Animal are affected in V acuo ; in what Man n . ]1dies, and is rev ved again . For this Purpose act

"ski;

Bladder is tied to a Pipe, and screwed into a

which then represents the Lungs in the Thorax. ^Pipe is perforated quite through to the Bladder, e<is the efore analogous to the Trachea or Wind'P.^ j,jThe Air confined in the Bottle about the Bladderthe fame Circumstances with that in the Breast A.the Lungs. When this Apparatus is placed un< T eReceiver, one or two Exfuctions will attenuate 1in the Receiver and Bladder, upon which the P^r,of included Air in the Bottle will compress the RAZ that in the Thorax does the Lungs j and a