. The Pharmaceutical era. cation which Is commonlyknown as Granulation. Torrefaction and Carbonization.—When the heat applied toa vegetable substance is sufficient to partially decomposeand drive off its volatile constituents, as in the roastingof coffee and the parching of corn, the process Is de-nominated Torrefaction. An example of the pharmaceutical use of torrefactionis seen in the preparation of the once popular, but nowrarely used, torrefied rhubarb. On roasting, the rhu-barb loses its cathartic properties, but retains its astrln-gency unimpaired. If the temperature is sufficient to com
. The Pharmaceutical era. cation which Is commonlyknown as Granulation. Torrefaction and Carbonization.—When the heat applied toa vegetable substance is sufficient to partially decomposeand drive off its volatile constituents, as in the roastingof coffee and the parching of corn, the process Is de-nominated Torrefaction. An example of the pharmaceutical use of torrefactionis seen in the preparation of the once popular, but nowrarely used, torrefied rhubarb. On roasting, the rhu-barb loses its cathartic properties, but retains its astrln-gency unimpaired. If the temperature is sufficient to completely drive off the volatile matters,leaving only the solidcarbon and inorganicconstituents behind,the process is knownas Carbonization. In carbonization theair must be excluded,or its admission care-fully regulated, other-wise the solid carbonwill Ignite and be con-sumed. Ignition. — Ignition isa general term appliedto any process ofstrongly heating asubstance in the airuntil all of its organicmatter is consumed or. Fig. 52.—Conducting An Ignition. all of its volatile matter expelled. When the process is applied to vegetable or animalmatter so as to completely burn away the solid carbon and leave an inorganic ash it is usually denominated In-cineration. When applied to inorganic matter, as theoxalates and carbonates of the alkaline earths, so as todrive off carbon dioxid, or other gas, and leave behind acalx or lime , it Is commonly known as Calcination. Ignitions are required mainly in analytical processes,and are conducted in small, cup-shaped vessels known ascrucibles, made of porcelain, plumbago, platinum, silver,etc., and heated by means of a blast lamp. (Fig. 52.) When a precipitate is to be ignited, it is thoroughlydried, removed from the filter paper, and the latter in-cinerated, at first being heated gently to drive off volatilematters, and then heated strongly to consume the solidcarbon. The precipitate is then added to the filter ash,and the whole heated fro
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