. The Pharmaceutical era. Fig. 46. 166 THE PHARMACEUTICAL ERA. [February 3, 1898. several seconds without ignition occurring. The experi-ment is made tlius: Place a few grains of gunpowder,close together, on a vire gauze; hold this about one inchaboTe a Bunseu burner, the air holes of which areclosed; turn on the gas supply fully, ignite the gas by ap-proaching it from above with a burning taper; keep itburning for a few seconds; turn it out before the entiregauze has time to become hot by conduction, and showthtit the powder is left unburnt. The second cone is the one to which light is due, a
. The Pharmaceutical era. Fig. 46. 166 THE PHARMACEUTICAL ERA. [February 3, 1898. several seconds without ignition occurring. The experi-ment is made tlius: Place a few grains of gunpowder,close together, on a vire gauze; hold this about one inchaboTe a Bunseu burner, the air holes of which areclosed; turn on the gas supply fully, ignite the gas by ap-proaching it from above with a burning taper; keep itburning for a few seconds; turn it out before the entiregauze has time to become hot by conduction, and showthtit the powder is left unburnt. The second cone is the one to which light is due, andthis luminosity is caused by particles of solid carbon. Fig. 47. heated to a white heat. The presence of this carbon maybe shown by holding in the flame a cold plate, for in-stance, a porcelain dish; this becomes covered by a blackdeposit of carbon. The reason for the temporary separation of element-ary carbon is that the hydrocarbons present are decom-posed, the more combustible hydrogen taking up the lim-ited quantity of oxygen which penetrates into this part ofthe flame, while carbon is set free. The liberated carbon,on reaching the outer cone, finds there suflicient oxygenwith which to combine. That the outer cone is the hottest part of the flame, andalso that free carbon is present in the middle cone, maybe shown by holding a thin platinum wire horizontally inthe flame. It will be noticed that the wire becomes rodhot where it passes through the outer cone, and thatcarbon is deposited where it was in contact with the mid-dle cone. Luminosity of Flames.—Bach individual substance must at-tain a specific temperatuTe before it emits ligh
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Keywords: ., bookcentury1800, booksubjectdrugs, booksubjectpharmacy, bookyear1
