The fluorescent tube also contains a small bit of mercury and an inert gas, typically argon, kept under very low pressure. As mentioned before, the tube has two electrodes, one at each end, powered by an alternating current.
When charged, the energy flowing between the electrodes changes some of the mercury in the tube from a liquid to a gas. As electrons and charged atoms move through the tube, some of them will collide with the gaseous mercury atoms.
The electrons in mercury release ultraviolet light. Our eyes don't register ultraviolet photons, so this sort of light needs to be converted into visible light to illuminate the lamp. Phosphors help this process.

 
 

Phosphors are substances that give off light when they are exposed to radiation. In a fluorescent lamp, the emitted light is in the visible spectrum -- the phosphor gives off white light we can see.

 
 
 

Before the discovery and application of phosphors, such a lamp was commonly used for various theraputic purposes. The specific type of radiation was identified as being beneficial for skin treatments, which was coupled with a second, much higher watt light bulb, warming the skin of the patient.

 

 
 
 
Almost fourty years after the company had formed, four star spangles were used in combination with the three wavy lines contained within a circle, to decorate the circular opening of a loudspeaker. The number of stars used in this early period varied. Examples exist of a single star spangle, a combination of two and a blanket of up to 12.
One of the first places of the logos appearance however, would be on the packaging for the 'Miniwatt' radio valve. These particular valves had at first been quite robust and would never really expire. As with commercial incandescent light they were later made to dysfunction after several years in order to retain an industry.
 
 

The fore mentioned circle emblem was consistently used on a wider variety of products and, therefore, received trademark status. However, when it was decided to apply for trademark registration, it turned out that a multinational chemical company had a similar circular trademark for the same or similar goods, making it impossible for the company to use its circular emblem and the word within a circle

 

So the word of the company, moved outside the circle and into a shield and the logo remained. The chemical company who had the other circular logo was, however no stranger. The company, our company, had also delved in the manufacture of chemicals, more specifically and quite prolifically, in the production of herbicides.