The Cathode Ray Tube site, Geissler tubes.

The Cathode Ray Tube site
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history and Physical Instruments

Johann Heinrich Geissler was a magnificent glassblower from a glass making family in Thuringen Germany, were he was a travelling instrument maker. After a decade he opened a shop in Bonn in 1855 to sell his scientific apparatus to schools and universities. In that same time Geissler developed a mercury vacuum pump, with this instrument he was able to take the most of the air out of the glass tubes and did experiments with rarified gas. When he now applied high tension to this tubes they produced a luminous effect.
This was the discovery of the first discharge light, in that time the beautiful tubes where used for demonstrations at Universities, schools and later on even for entertainment-home use. In the time that there was only carbon light this was a rare phenomena. Also high vacuum tubes were now possible to make, this led to many discoveries of physical instruments like the different Crookes, Hittorf and Goldstein tubes.
In the beginning of the 20th Century many Geissler tubes were produced by Rudolf Pressler who learned his skills in Leipzig and started in 1903 his Pressler company in Cursdorf-Thuringen Germany.
The tube makers often used uranium glass, fluorescent liquid and different types of rarified gas to make the most beautiful luminous compositions. The tubes where discharged by use of a Ruhmkorff coil, this produced the high tension needed to lighten the tubes. Geissler tubes are real pieces of art and are rare collectors items, they are however still made by some glassblowers in Germany. The British Science Museum in London displays top art from Heinrich Geissler. In Thuringen / Cursdorf there is a also museum dedicated to Geissler's work. The complete biography of Geissler can be found on the excellent site of Eugenii Katz.

Johann Heinrich Geissler
1815-1879

In these three Christie's catalogues you can find a lot of amazing tubes.

The Christie's catalogue from 1998 contains a great collection of Geissler and Crookes tubes from the former
Pressler factory. Made before WWII, a part of the produced tubes were stored in other buildings for secure reasons
but they were forgotten for a long time. After the war in the DDR time the factory was renamed in VEB and produced
mainly radiometers. When the Berlin wall fell, the stored tube collection was rediscovered. That's one story... the
other is that the tubes were made after WWII by former Pressler employees with remaining part stock of the
old Pressler factory, so the tubes are not antique or old. Due to this fact Christie's cancelled the auction, but
the catalogue was already made at that time. The tubes, some times for sale at auction sites, are still fine examples
of the old glassblowing skills and are true collector items.

An old drawing of different types of Geissler tubes.

A small 10cm Geissler tube early 20'th century with transparent fluorescent fluid in a second glass jacket.

Close-up of the interior of the Geissler tube under influence of UV light.

End caps
It is difficult to date Geissler tubes and Crookes tubes, the electrode connection is often the most simple and reliable age mark. The oldest tubes from the late 19th and beginning of the 20th century are equipped with wire loops, followed by small copper or brass caps, later on cylindrical end caps were used. The youngest tubes have end caps similar to the anode cap on regular radio tubes.

Fluids
The fluids used in old Geissler tubes give the tube an enhanced effect. Some bigger tubes can be externally filled in a separate chamber around the vacuum tube to experiment with different fluids.

Quinine, a light yellow fluid - bright blue fluorescent.
Fluorescein. yellow fluid.
Rosaniline, magenta fluid.
Magdalared or Sudanred, red fluid.

Glass
The early old tubes are made of soft soda lime glass. The tubes which are made today are made of modern Pyrex glass.

There are fantastic designs of Geissler tubes.
You can find nice collections at the websites of:
The Sparkmuseum
Die fazination: Glas-Hochspannung-Vakuum-Licht
Kenyon College
O'Neills Electronic Museum

Nice collection of 4 Geissler tubes and an early electrotherapy tube with uranium glass, predecessor of the violet ray tube.
Picture courtesy of Alastair Wright.

The Cathode Ray Tube site

A Spectral tube emits certain wavelengths of light (color) in the capillary-thin tube
in the middle. This color depends on the type of noble gas or vapor inside the tube.
The different spectra of colors can be seen by use of a prism.
These tubes were used for spectroscopy classroom demonstrations.

Spectral tubes (Pressler)

Activated Pressler spectral CO tube.

Collection of 3 small Geissler tubes with uranium glass.

Uranium glass also called Vaseline glass was
widely used in Geissler tube production, it
contains uranium salts (uranium dioxide) this is
a natural product, when added to glass it gives a
nice green color. This is caused by the
radioactive nature of the salt. Unless the
measurable radioactivity it's not harmful for
normal use, unless you eat it. (not recommended)