ACTION OF THE BLOWPIPE.

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those containing arsenic, an alliaceous odor, those containing sele-nium, the odor of horse-radish : the emission of light below a redheat, called phosphorescence.

2. During and after fusion : the change of color, and the evo-lution of odorous fumes, as above : the similarity, or dissimilarity,between the color of the melted and subsequently cooled globule:the frothing or intumescence, produced by the escape of aerial mat-ter : the fluidity and general appearance of the fused globule orsurface: the nature of the cooled globule, whether angular andcrystalline in its form, glassy, vesicular, scoriaceous, opaque ordiaphanous, free or covered with a thin incrustation, capable ofaffecting the magnetic needle or attractable by the magnet, metallicor unmetallic; and if metallic, whether malleable or brittle.

It should also be observed whether the support is covered withan incrustation, and the color and nature of this coating.

For a more complete account of the phenomena attending theuse of this instrument, and of its effects as indicative of the composi-tion of minerals, reference may be made to a very complete andhighly valuable work on this subject, by Berzelius , which has beentranslated by Mr. Children*

♦ The use of the blowpipe in Chemical Analysis, and in the examination of Mine-rals : translated by J. G. Children. 8vo. 3 pi. London, 1822.