Fire was the first source of light, which man learned how to use it. It had been used
for a very long time, but the grate is not a good source of heat and so people devised a
chip of resinous kindling wood – they were chosen suitable dry sticks, painted them with
resin and impregnated them with fat. The top of this type of light fitting were the
torches commonly used even in the Middle Ages. Since about the 1st century BC
the candles have been used. The most suitable and also the most expensive were those made
from wax. Today the candles are usually made from the compound of stearin and paraffin,
the wick is made from a cotton contexture. Here we should mention, that the gas arose by
evaporation of the candle’s skin is the thing that is burning and lighting, not the wick
as many people think. The wick serves just like a capillary, that brings the liquefied
fuel by the help of capillarity. Troubles were made by the fact, that the wick was sacking
more slowly than the candle’s skin and it was necessary to abbreviate it. First after
thousand years of the candle’s existence – in 1834 – a wick was devised, which could
burn away absolutely. Much more spread and also cheaper were the oil burners. It has
remained in an unchanged form for several thousand years.
Ancient ceramic
lamp
After the scrolling of a wick (known already in antiquity) and the use of a
glass cylinder were spread, the petroleum lamps were devised, this happened in 1855 and
shortly after this the oil lamp was displaced. The petroleum lamps spread very quickly,
because petroleum was much suitable for lighting then the oil. Though people used also
petrol for lighting (but rather rarely). The exception here is the so called “Davy´s
mining burner”. Sir Humphry Davy devised this burner for the work in the mines,
where the air contains the explosive commixture of gases. He solved this problem this way:
he separated the flame of the petrol lamp from the surrounding air with a dense metal
grating. When the gas comes through this grating it is cooled in so far, that it cannot
fire the gases in the air. The honour of the deviser we should say that he had never this
device patented …
Classic table
petroleum lamp
Despite of the advantages, the petroleum lamp was gradually loosing its dominant
position. This began in the times when another device was coming to light: the automobile.
It was necessary to find such source of light, which would allow travelling at night. The
actual lamps were suitable just for carriages or fiacres. And so the acetylene light was
born. The acetylene arises during the reaction of calcium carbide with water. Its flame is
very bright and its production very easy: you just stir the calcium carbide with water.
However it also explodes very easily. Though in mining the carbide-lamps survived the half
of this century. Today we can meet with acetylene only when welding or soldering. The real
development of the gas-lighting was possible when the coal-gas was invented (made from
coal or wood). Abstractedly from each other two names started to appear: William
Murdoch and Phillippe Lebon. Mudrock, the British engineer and deviser
(colleague of James Watt) devised the lighting with coal-gas in 1792 already and later he
became the “father” of the gas-lighting in England. Lebon, the French chemist
did not received a patent for a gas-lamp until 1799. He survived his patent for only 5
years: in 1804 he was murdered (13 hits with a dagger) when preparing the lighting for the
Napoleon's coronation. The gas-lighting had two grand advantages: the wick was not
necessary and from one source it was possible to light great number of lamps. But one big
disadvantage remained: every lamp had to be lit on and off. Moreover the new source of
energy – the electricity was asserting itself. The gas-lighting could be saved only by
something great and grand. The man, who solved this problem to perfection was the Austrian
chemist Carl Auer, baron von Welsbach. The grand news was so called hot-bulb
mantle. Auer's mantle, which contained the oxides of cerium and thorium, was put on
the flame. So not the flame but the mantle was lighting. The gas-lamps survived their
death …
Gas lamp with two
burners with mantles
Previously mentioned chemist Davy found out, when doing his experiments,
that the platinum wire emblazes and lights when the electricity goes through it. Later he
found out another thing: a lighting arc arises between two spikes of charred wood (carbon
electrodes) when the electricity power is lead there. But it was to soon to realise these
ideas. Mainly because it was necessary to find the right material for making the
electrodes and to assure the constant distance between the both ends of electrodes where
the arc was burning. The French physicist Jean Bernard Leon Foucault, member of the
French Academy of Sciences and the Royal company in London, was the first man who
fulfilled these conditions. The electrodes were adjusted in one axe and their shift was
assured with a rather complicated apparatus. The same problem was solved a bit later but
much more elegantly by the Russian military engineer living in France Pavel Nikolajevic
Jablockov: he placed the both electrodes next to each other in a parallel way and in
the optimal distance (this was assure by the combustible insulating material between the
electrodes). The electrodes were diminishing but the in advance set distance was always
constant: without difficult regulation, without a difficult apparatus. Many devisers took
part in the improvement of the arc lamp. Among them there was also the Czech
electro-technician Frantisek Krizik who received the first prize on the
exhibition in Paris in 1881 for his improved type of the arc-lamp with solenoid. But the
arc-lamps had one grate disadvantage: rather short lifetime of the electrodes. This fault
was cleared away but there was another competitor: the bulb.
Arc lamp
Krizik-Piette
Thomas Alva Edison is often indicated as its inventor – mainly in different
encyclopaedias. But it is definite, that the bulbs had existed even before Edison.
E.g. the German watchmaker H. Goebel, who made a bulb with a carbon fibre in a
vacuous glass bulb and used it for his advertising on the roof of his house in New York. Edison's
merit consists “only” in the fact, that he made them the wide-spread practical
light-fitting.
Edison at his lab
Just like for the other also for Edison the main problem was to find the
suitable material for the bulb fibre. Edison had never been a scientific worker and
he hated mathematics. He reached his results by doing many – and often very accidental
– experiments. It was the same when he was searching the right material for the fibre.
After many experiments he tried the cotton. After few tries he succeeded in fixing the
charred fibre in the glass bulb, sucking out the air and fluxing it. After connecting it
into the electricity the bulb had been shining for 45 hours: this happened on 21st
and 22nd October 1879. To prolong the lifetime of the bulb Edison tried
to char everything he could think of. After 6.000 experiments the bamboo seemed to be the
right thing. In 1881 the steam-boat (!) Columbia was shining with the light of
350 bulbs.
Edison's two-filament bulb
The lifetime of these Edison's bulbs was 300 hours, later it was
increased up to 600 hours. The nowadays bulbs can shine for about 1.000 hours and have
much higher light efficiency. But there is not the carbon fibre in them anymore, there is
usually the wolfram fibre (0,75 m of a fibre, which is thinner than 1/4 of a human hair).
Also the vacuum was replaced: first with nitrogen and today most often with 88% of argon
and 12% of nitrogen. Only the winding remained after Edison …
Despite of all improvements even the nowadays bulbs are inefficient. 95 % of the
delivered energy turns into warmth and just 5% into light. A bit more saving are the
halogen bulbs – bulbs filled with the gas that contains admixture of certain amount of
halogens (e.g. iodine). But their use is limited (automobiles).
Halogen reflector lamp (from page
http://www.sylvania.com/prodinfo/business/halogen/mr16.htm)
