Bristol). He replied immediately and said he would visit Newcastle on

Bristol). He replied immediately and said he would visit Newcastle on his return journey so as to investigate the problem. This he did in August 1815, when he spent some days in discussion with colliery owners and, in particular, with Mr Buddle (of the Wallsend Colliery)–an influential person on Tyneside and County Durham–who had endeavoured to minimize the risk of explosions by forced ventilation of his mines. Davy quickly ascertained the nature of the problem, and he acquired, for his return to the RI, bulk samples of fire-damp from various sources in the mines. In his laboratory, he reassured himself that fire-damp was, indeed (as had been demonstrated earlier by Henry and by Dalton), methane, CH4 . He set about investigating the range of concentrations in which fire-damp formed an explosive mixture with air, and then focused his attention on the degree of heat needed to ignite it. He discovered that fire-damp was relatively harder to ignite than explosive mixtures of air with H2 or carbonic oxide (CO) or olefiant gas (ethylene, C2 H4 ). For the ignition of firedamp, a higher temperature was required. Next, he studied the expansion that occurred on the explosion of various mixtures and their power of communicating flame RWJ 64809 clinical trials through apertures to other explosive mixtures. These experiments yielded the clue that led him to the ultimate solution. He investigated the movement of the flame of an explosive mixture of coal gas (which consists mainly of H2 , CO and C2 H4 ) and air in a tube one-quarter of an inch in GSK2256098 chemical information diameter and one foot long. He found that it took a second to travel from one end to the other. When the diameter of the tube was reduced to one-seventh of an inch he found that he could not make the mixture explode, although coal gas was more explosive than fire-damp. He then exploded mixtures of fire-damp via a jar connected with a bladder filled with the same mixture by means of a stopcock with an aperture of one-sixth of an inch and found that the flame did not ignite the gas in the bladder. On comparing the effect of connections between the jar and the bladder made of glass and metal, he noted that flames passed more readily through glass tubes than metal tubes of the same diameter, a fact that he attributed to the higher thermal conductivity of the metal and, hence, the cooling it produced, bearing in mind his earlier observation that–in his own words–the fire-damp requires a very strong heat for inflammation. Davy also established that the explosion would not pass through metal slots if their diameter was less than one-seventh of an inch, provided they were of sufficient length, nor would it pass through fine wire-gauze. The latter was an important discovery. He then examined the effect of mixing CO2 or N2 (azote) with the explosive mixture and found that the presence of one part of N2 in six parts of the explosive mixture deprived it of its explosive power. He obtained the same result with one part of CO2 in seven parts of the mixture. He concluded that this effect was attributable to the cooling of the flame by this admixture of an `inert’ gas. Equipped with all of these fundamental, experimental facts, Davy possessed sufficient evidence to design his first safety lamp in which, by admitting only a limited supply of air to an oil burner, in a closed lantern, the amount of CO2 and N2 would be sufficient to prevent an explosionrsta.royalsocietypublishing.org Phil. Trans. R. Soc. A 373:………………………………..Bristol). He replied immediately and said he would visit Newcastle on his return journey so as to investigate the problem. This he did in August 1815, when he spent some days in discussion with colliery owners and, in particular, with Mr Buddle (of the Wallsend Colliery)–an influential person on Tyneside and County Durham–who had endeavoured to minimize the risk of explosions by forced ventilation of his mines. Davy quickly ascertained the nature of the problem, and he acquired, for his return to the RI, bulk samples of fire-damp from various sources in the mines. In his laboratory, he reassured himself that fire-damp was, indeed (as had been demonstrated earlier by Henry and by Dalton), methane, CH4 . He set about investigating the range of concentrations in which fire-damp formed an explosive mixture with air, and then focused his attention on the degree of heat needed to ignite it. He discovered that fire-damp was relatively harder to ignite than explosive mixtures of air with H2 or carbonic oxide (CO) or olefiant gas (ethylene, C2 H4 ). For the ignition of firedamp, a higher temperature was required. Next, he studied the expansion that occurred on the explosion of various mixtures and their power of communicating flame through apertures to other explosive mixtures. These experiments yielded the clue that led him to the ultimate solution. He investigated the movement of the flame of an explosive mixture of coal gas (which consists mainly of H2 , CO and C2 H4 ) and air in a tube one-quarter of an inch in diameter and one foot long. He found that it took a second to travel from one end to the other. When the diameter of the tube was reduced to one-seventh of an inch he found that he could not make the mixture explode, although coal gas was more explosive than fire-damp. He then exploded mixtures of fire-damp via a jar connected with a bladder filled with the same mixture by means of a stopcock with an aperture of one-sixth of an inch and found that the flame did not ignite the gas in the bladder. On comparing the effect of connections between the jar and the bladder made of glass and metal, he noted that flames passed more readily through glass tubes than metal tubes of the same diameter, a fact that he attributed to the higher thermal conductivity of the metal and, hence, the cooling it produced, bearing in mind his earlier observation that–in his own words–the fire-damp requires a very strong heat for inflammation. Davy also established that the explosion would not pass through metal slots if their diameter was less than one-seventh of an inch, provided they were of sufficient length, nor would it pass through fine wire-gauze. The latter was an important discovery. He then examined the effect of mixing CO2 or N2 (azote) with the explosive mixture and found that the presence of one part of N2 in six parts of the explosive mixture deprived it of its explosive power. He obtained the same result with one part of CO2 in seven parts of the mixture. He concluded that this effect was attributable to the cooling of the flame by this admixture of an `inert’ gas. Equipped with all of these fundamental, experimental facts, Davy possessed sufficient evidence to design his first safety lamp in which, by admitting only a limited supply of air to an oil burner, in a closed lantern, the amount of CO2 and N2 would be sufficient to prevent an explosionrsta.royalsocietypublishing.org Phil. Trans. R. Soc. A 373:………………………………..

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