At the end of the nineteenth century, luminous signs were a new phenomenon.
neon
Luminous signs are easier to find when there is an emergency.
.
The gas used in fluorescent lamps is argon. Neon is used for red lamps.
The blue flame is used because it is the hottest.
Its mostly Argon and a small amount of mercury. Its the main ingredients inside a flourescent lightbulb, which are used to light up billboards and highway signs. See the related link for more information on flourescent bulbs.
Non- luminous flame should be used as it is steady and produces little or no soot.
radium was used in luminous paint and for theglow in the dark clock it as it emits radioactive decay that's why its not used in luminous paint now
Non-luminous flame should be used for heating in the laboratory because the flame is steady and produce little or no soot.Non-luminous flame is very hot thus, it is recommendable to use for laboratory purposes.Luminous flame is unsteady while non-luminous flame is steady.Another reason of using non-luminous flame because the flame of non-luminous is blue, and not visible unlike the luminous flame which is yellow in colour and visible.
The SI unit of luminous intensity is the candela.
egyptians
Promethium can be used in luminous paints.