In 1899, J. J. Thomson investigated ultraviolet light in Crookes tubes.

William Crookes investigated the effects of energy discharges on rare gases.

By 1862, Crookes was able to isolate small quantities of the new element and determine the properties of a few compounds.

It was used by Crookes, Johann Hittorf, Juliusz Plücker, Eugen Goldstein, Heinrich Hertz, Philipp Lenard and others to discover the properties of cathode rays, culminating in J. J. Thomson's 1897 identification of cathode rays as negatively-charged particles, which were later named electrons.

Many ingenious types of Crookes tubes were built to determine the properties of cathode rays ( see below ).

A is a low voltage power supply to heat cathode C ( a " cold cathode " was used by Crookes ).

In the early cold cathode vacuum tubes, called Crookes tubes, this was done by using a high electrical potential between the anode and the cathode to ionize the residual gas in the tube ; the ions were accelerated by the electric field and released electrons when they collided with the cathode.

This came to be called the " cathode dark space ", " Faraday dark space " or " Crookes dark space ".

Crookes found that as he pumped more air out of the tubes, the Faraday dark space spread down the tube from the cathode toward the anode, until the tube was totally dark.

The gas ionization ( or cold cathode ) method of producing cathode rays used in Crookes tubes was unreliable, because it depended on the pressure of the residual air in the tube.

The first true electronic vacuum tubes, invented around 1906, used this hot cathode technique, and they superseded Crookes tubes.

The ionization method of creating cathode rays used in Crookes tubes is today only used in a few specialized gas discharge tubes such as krytrons.

He also developed the Crookes tubes, investigating cathode rays

Following the discovery of X-rays by Wilhelm Röntgen in 1895, Miller used cathode ray tubes built by William Crookes to make some of the first photographic images of concealed objects, including a bullet within a man's limb.

* William Crookes invents the Crookes tube which produces cathode rays.

* 1875 – William Crookes invented the Crookes tube and studied cathode rays

An electric glow discharge tube featuring its most important characteristics: ( a ) An anode at one end and cathode at the other end ( b ) Aston Dark Space ( c ) Cathode glow ( d ) Cathode dark space ( also called Crookes dark space, or Hittorf dark space ) ( e ) Negative glow ( f ) Faraday space ( g ) Positive column ( h ) Anode glow ( i ) Anode dark space.

These first generation cold cathode or Crookes X-ray tubes were used until the 1920s.

An electric glow discharge tube featuring its most important characteristics: ( a ) An anode and cathode at each end ( b ) Aston Dark Space ( c ) Cathode glow ( d ) Cathode dark space ( also called Crookes dark space, or Hittorf dark space ) ( e ) Negative glow ( f ) Faraday space ( g ) Positive column ( h ) Anode glow ( i ) Anode dark space. Hopkinson builds a team of researchers, one of whom is Harry Ricardo, the engineer who makes his name for his pioneering work on internal combustion engines.

A Crookes tube is an early experimental electrical discharge tube, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were discovered.

Cathode rays casting a shadow on the wall of a Crookes tube

Crookes had stated that there may be parts of the human brain that may be capable of sending and receiving electrical rays of wavelengths.

William Crookes developed a modification of the Geissler tube into what is known as the Crookes tube to demonstrate and study these rays, later determined to be a stream of electrons.

Crookes tubes are now used only for demonstrating cathode rays.

The ionization method of creating cathode rays used in Crookes tubes is today only used in a few specialized gas discharge tubes such as krytrons.

Crookes tubes were used in dozens of historic experiments to try to find out what cathode rays were.

Crookes put a tiny vaned turbine or paddlewheel in the path of the cathode rays, and found that it rotated when the rays hit it.

Crookes concluded at the time that this showed that cathode rays had momentum, so the rays were likely matter particles.

If the glow discharge seen in the gas of Crookes tubes was produced by the moving cathode rays, the light radiated from them in the direction they were moving, down the tube, would be shifted in frequency due to the Doppler effect.

Diagram showing a Crookes tube circuit.

Crookes and Artur Shuster believed they were particles of " radiant matter ", that is, electrically charged atoms.

Crookes tubes generated the electrons needed to create X-rays by ionization of the residual air in the tube, instead of a heated filament, so they were partially but not completely evacuated.

The sugar cane fields on the outskirts of Umzinto are owned and run by Crookes Brothers a JSE listed company. they are still thriving.

Geist mentioned that Green Party of Canada financier Wayne Crookes filed a suit in which he alleged damages for an online news service that republished resignation letters from that party and let users summarize claims they contained.

Crookes tubes are cold cathode tubes, meaning that they do not have a heated filament in them that releases electrons like the later electronic vacuum tubes usually do.

They were accelerated to a high velocity by the electric field between the electrodes, both because they didn't lose energy to collisions, and also because Crookes tubes required a higher voltage.

When the voltage applied to a Crookes tube is high enough, around 5, 000 volts or greater, it can accelerate the electrons to a fast enough velocity to create X-rays when they hit the anode or the glass wall of the tube.

Many early Crookes tubes undoubtedly generated X-rays, because early researchers such as Ivan Pulyui had noticed that they could make foggy marks on nearby unexposed photographic plates.

There were two theories: British scientists Crookes and Cromwell Varley believed they were ' corpuscles ' or ' radiant matter ', that is, electrically charged atoms.

Both Einstein's and Reynolds's forces appear to cause a Crookes radiometer to rotate, although it still isn't clear which one is stronger.

X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered in the late 19th century, and the availability of this controllable source of X-rays created the field of radiography, the imaging of opaque objects with penetrating radiation.