Chemistry : general, medical, and pharmaceutical including the chemistry of the ; a manual on the general principles of the science, and their applications in medicine and pharmacy . stances burning in air, the conditions are, practically,always the same : hence no confusion arises from regarding air as thegreat supporter of combustion, and bodies which burn in it as beingcombustible. Structure of Flame.—A candle-flame or oil-flame is a jet of gasintensely heated; the central portion is unburnt gas; the next envel-ope is formed of partially burnt and very dense, gaseous, and s
Chemistry : general, medical, and pharmaceutical including the chemistry of the ; a manual on the general principles of the science, and their applications in medicine and pharmacy . stances burning in air, the conditions are, practically,always the same : hence no confusion arises from regarding air as thegreat supporter of combustion, and bodies which burn in it as beingcombustible. Structure of Flame.—A candle-flame or oil-flame is a jet of gasintensely heated; the central portion is unburnt gas; the next envel-ope is formed of partially burnt and very dense, gaseous, and solidparticles, heated sufficiently high to give light, and the outer cone ofcompletely burnt gases. In the figure the sharpness of limit of thesecones is purposely somewhat exaggerated. Air made, by any me-chanical contrivance of burner, to mix with the interior of a flame atonce burns up, or perhaps prevents the formation of dense gases givinga hotter, but non-luminous, jet. The air-gas lamps (Fig. 7), orBunsen gas-burners commonly used in chemical laboratories areconstructed on this principle ; their flame has the additional advantageof not yielding a deposition of soot. Fipr. 6. Fiff. iStructure of Flame. Bunseu or Air-gas Burner. In the air-gas lamp, coal-gas escaping from a small orifice drawsrather more than twice its volume of air (supplied through adjacentholes) into its column, and the mixture of gas and air passes upwardsalong a pipe. It only burns at the end, and not within the pipe,partly because the metal of the burner, by conducting heat away,cools the mixture below the temperature at which it can ignite;partly because the velocity with which the mixture flows out is greaterthan the rate at which such a mixture ignites; and partly because theproportion of air to gas in this mixture is insufficient for thorough andperfect combustion, the external air contributing materially to thecomplete combustion of the jet of air-gas. The Davy safety-lampacts on the first
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Keywords: ., bookcentury1, bookdecade1870, booksubjectpharmaceuticalchemistry
