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In a vacuum; in empty space; as, experiments in vacuo.

ght is produced by a thin filament of conducting material, usually carbon, contained in a vacuum, and heated to incandescence by an electric current, as in the Edison lamp; -- called also incandescence lamp, and glowlamp.

The act of throwing cold water into a condenser to produce a vacuum.

e of peculiar construction, adapted for drawing blood from a scarified part by means of a vacuum. Horse leech, a less powerful European leech (Hæmopis vorax), commonly attacking the membrane that lines the inside of the mouth and nostrils of animals that drink at pools where it lives.

ny material permeable by cathode rays, as aluminium, which forms a portion of a wall of a vacuum tube, or which is mounted within the tube and exposed to radiation from the cathode. Lenard rays are similar in all their known properties to cathode rays. So called from the German physicist Philipp Lenard (b. 1862), who f…

agnetic reluctance or resistance, equal to the reluctance of a centimeter cube of air (or vacuum) between parallel faces. Also, a reluctance in which unit magnetomotive force sets up unit flux.

A closed vessel for boiling or evaporating. See Vacuum pan, under Vacuum.

That state in which every part of space is supposed to be full of matter; -- opposed to vacuum. G. Francis.

A vacuum tube, used in spectrum analysis, in which the part through which the discharge takes place is a capillary tube, thus producing intense incandescence of the contained gases.

s to test the flatness of a stone. -- Proof stick (Sugar Manuf.), a rod in the side of a vacuum pan, for testing the consistency of the sirup. -- Proof text, a passage of Scripture used to prove a doctrine. proof coin or proof, a coin which has been specially struck, to produce the finest specimen of its type.…

ct action of the steam on the water, without the intervention of a piston; -- also called vacuum pump.

il of rays. -- Röntgen ray ( (Phys.), a kind of ray generated in a very highly exhausted vacuum tube by the electrical discharge. It is capable of passing through many bodies opaque to light, and producing photographic and fluorescent effects by which means pictures showing the internal structure of opaque objects are…

The glass vessel in which the vacuum is produced, and the objects of experiment are put, in experiments with an air pump. Cf. Bell jar, and see Illust. of Air pump.

index (Opt.), the index of refraction of a substances when the ray passes into it from a vacuum. -- Relative refractive index (of two media) (Opt.), the ratio of the sine of the angle of incidence to the sine of the angle of refraction for a ray passing out of one of the media into the other.

of the rays produced when cathode rays strike upon surface of a solid (as the wall of the vacuum tube). Röntgen rays are noted for their penetration of many opaque substances, as wood and flesh, their action on photographic plates, and their fluorescent effects. They were called X rays by their discoverer, W. K. Röntge…

gazogene, and siphoid. -- Siphon condenser, a condenser for a steam engine, in which the vacuum is maintained by the downward flow of water through a vertical pipe of great height. -- Siphon cup, a cup with a siphon attached for carrying off any liquid in it; specifically (Mach.), an oil cup in which oil is carried o…

To draw, as a liquid, by the action of the mouth and tongue, which tends to produce a vacuum, and causes the liquid to rush in by atmospheric pressure; to draw, or apply force to, by exhausting the air.

and hermetically sealed at the upper, such as is used in the barometer. -- Torricellian vacuum (Physics), a vacuum produced by filling with a fluid, as mercury, a tube hermetically closed at one end, and, after immersing the other end in a vessel of the same fluid, allowing the inclosed fluid to descend till it is co…

Empty space; vacuity; vacuum. How is't with you, That you do bend your eye on vacancy Shak.

the space between the bodies of the universe, or the molecules and atoms of matter., is a vacuum; -- opposed to plenist.