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Article THE CHEMISTRY OF COMMON THINGS, ← Page 5 of 5
Note: This text has been automatically extracted via Optical Character Recognition (OCR) software.
The Chemistry Of Common Things,
inside , as well as the outside , ox the flame to be exposed to the influence of the air . There is , consequently , no dark spot to be seen , as the whole of the smoke is consumed as soon as it escapes from the ¦ ' i- wua ¦ flQ . w » ri in + > iici ocictA k surrhnnded bv a glass chimney , jjlv ^^ ~— ~— ¦;
wick , --, u ^ "" - — ; •* ° ,. / . , r which , by creating a strong current , aids m-the consumption oi the smoke , and increases the intensity of the . light . The . current is produced in this case by the heated and rarefied air from the lamp rising rapidly up the chimney , and causing the cold air from outside to rush in at the bottom to supply its place . Such an arrangement is called an Argand burner . n t
In the case of a gas burner , the two first processes , viz ., liquefaction and decomposition , are both omitted ; for as coal gas is composed of iincombined hydrogen and carbon , it is already in a fit state to unite with the oxygen of the atmosphere . It therefore , when once lighted , continues to bum , as soon as it issues from the mouth of the pipe . There is . one remarkable property of flame which must noi oe passea over . Elaine requires such intense heat for its maintenance , that the
application of a piece of cold metal of sufficient size will extinguish it by abstracting its heat . For the same reason it will not pass between two metal bars placed very close together , nor through wire gauze . If a piece of iron gauze ' or metal pierced with small holes be held ov er the wiek of a candle , it will be seen that the flame cannot pass through it . Noticing- this phenomenon , it occurred to Davy that if a candle or
lamp were completely surrounded with fine wire gauze , it might be plunged into the most explosive gases with impunity , the gauze preventing the flame from passing through its meshes and igniting the explosive mixture outside , but still allowing the mixture to pass inside and feed the flame by means of the . air which it contains . The gases would , therefore , burn quietly inside the lamp , which would be filled .
with flame . Acting upon , these ideas , he succeeded . m producing the lamp which bears his name , and which was designed for the protection of miners , enabling them to use a light in their occupation without fear of any disastrous results . We have before men tinned that when oxygen and hydrogen are
mixed together in certain proportions , and name is applied , an explosion is the result . ' . But this explosion does not only take place when pure oxygen and hydrogen are combined . Goal gas is a kind of . ; . impure hydrogen , being a mixture of that gas with carbon or charcoal , and when this is mixed with common air , which is composed of oxygon . and nitrogen , explosion takes place on the application of flame . N 'ow coal mines are very frequently filled with such a mixture , which ex-... 1 _ 1 • .- .. •» . 1 « K .. ill ' "i I 1 in violence tir
pioaes stantly with , tremendous , and generally tatal , on . e application of a naked light . 'Tlie frightful , colliery explosions that we so constantly hear of are instances of this . But when the light is properly inclosed , with such a wire covering as has been described , it may be safely used by the workmen , even when 'the mine is highly ' / hargod with gas , and it may be seen by the appearance of the flame ' mside , what is the proportion of air and gas in that part of the mine .
Note: This text has been automatically extracted via Optical Character Recognition (OCR) software.
The Chemistry Of Common Things,
inside , as well as the outside , ox the flame to be exposed to the influence of the air . There is , consequently , no dark spot to be seen , as the whole of the smoke is consumed as soon as it escapes from the ¦ ' i- wua ¦ flQ . w » ri in + > iici ocictA k surrhnnded bv a glass chimney , jjlv ^^ ~— ~— ¦;
wick , --, u ^ "" - — ; •* ° ,. / . , r which , by creating a strong current , aids m-the consumption oi the smoke , and increases the intensity of the . light . The . current is produced in this case by the heated and rarefied air from the lamp rising rapidly up the chimney , and causing the cold air from outside to rush in at the bottom to supply its place . Such an arrangement is called an Argand burner . n t
In the case of a gas burner , the two first processes , viz ., liquefaction and decomposition , are both omitted ; for as coal gas is composed of iincombined hydrogen and carbon , it is already in a fit state to unite with the oxygen of the atmosphere . It therefore , when once lighted , continues to bum , as soon as it issues from the mouth of the pipe . There is . one remarkable property of flame which must noi oe passea over . Elaine requires such intense heat for its maintenance , that the
application of a piece of cold metal of sufficient size will extinguish it by abstracting its heat . For the same reason it will not pass between two metal bars placed very close together , nor through wire gauze . If a piece of iron gauze ' or metal pierced with small holes be held ov er the wiek of a candle , it will be seen that the flame cannot pass through it . Noticing- this phenomenon , it occurred to Davy that if a candle or
lamp were completely surrounded with fine wire gauze , it might be plunged into the most explosive gases with impunity , the gauze preventing the flame from passing through its meshes and igniting the explosive mixture outside , but still allowing the mixture to pass inside and feed the flame by means of the . air which it contains . The gases would , therefore , burn quietly inside the lamp , which would be filled .
with flame . Acting upon , these ideas , he succeeded . m producing the lamp which bears his name , and which was designed for the protection of miners , enabling them to use a light in their occupation without fear of any disastrous results . We have before men tinned that when oxygen and hydrogen are
mixed together in certain proportions , and name is applied , an explosion is the result . ' . But this explosion does not only take place when pure oxygen and hydrogen are combined . Goal gas is a kind of . ; . impure hydrogen , being a mixture of that gas with carbon or charcoal , and when this is mixed with common air , which is composed of oxygon . and nitrogen , explosion takes place on the application of flame . N 'ow coal mines are very frequently filled with such a mixture , which ex-... 1 _ 1 • .- .. •» . 1 « K .. ill ' "i I 1 in violence tir
pioaes stantly with , tremendous , and generally tatal , on . e application of a naked light . 'Tlie frightful , colliery explosions that we so constantly hear of are instances of this . But when the light is properly inclosed , with such a wire covering as has been described , it may be safely used by the workmen , even when 'the mine is highly ' / hargod with gas , and it may be seen by the appearance of the flame ' mside , what is the proportion of air and gas in that part of the mine .