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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Crucible | 3/3 | https://en.wikipedia.org/wiki/Crucible | reference | science, encyclopedia | 2026-05-05T10:04:04.364838+00:00 | kb-cron |
In the area of chemical analysis, crucibles are used in quantitative gravimetric chemical analysis (analysis by measuring mass of an analyte or its derivative). Common crucible use may be as follows. A residue or precipitate in a chemical analysis method can be collected or filtered from some sample or solution on special "ashless" filter paper. The crucible and lid to be used are pre-weighed very accurately on an analytical balance. After some possible washing and/or pre-drying of this filtrate, the residue on the filter paper can be placed in the crucible and fired (heated at very high temperature) until all the volatiles and moisture are driven out of the sample residue in the crucible. The "ashless" filter paper is completely burned up in this process. The crucible with the sample and lid is allowed to cool in a desiccator. The crucible and lid with the sample inside are weighed very accurately again only after it has completely cooled to room temperature (higher temperature would cause air currents around the balance giving inaccurate results). The mass of the empty, pre-weighed crucible and lid is subtracted from this result to yield the mass of the completely dried residue in the crucible. A crucible with a bottom perforated with small holes which are designed specifically for use in filtration, especially for gravimetric analysis as just described, is called a Gooch crucible after its inventor, Frank Austin Gooch. For completely accurate results, the crucible is handled with clean tongs because fingerprints can add a weighable mass to the crucible. Porcelain crucibles are hygroscopic, i. e. they absorb a bit of weighable moisture from the air. For this reason, the porcelain crucible and lid is also pre-fired (pre-heating to high temperature) to constant mass before the pre-weighing. This determines the mass of the completely dry crucible and lid. At least two firings, coolings, and weighings resulting in exactly the same mass are needed to confirm the constant (completely dry) mass of the crucible and lid and similarly again for the crucible, lid, and sample residue inside. Since the mass of every crucible and lid is different, the pre-firing/pre-weighing must be done for every new crucible/lid used. The desiccator contains desiccant to absorb moisture from the air inside, so the air inside will be completely dry.
== See also == Hessian crucible Micro-pulling-down Ladle (metallurgy) Wax melter
== References ==
== Bibliography == Craddock P., 1995, Early Metal Mining and Production, Edinburgh University Press Ltd, Edinburgh Hauptmann A., T. Rehren & Schmitt-Strecker S., 2003, Early Bronze Age copper metallurgy at Shahr-i Sokhta (Iran), reconsidered, T. Stollner, G. Korlin, G. Steffens & J. Cierny, Eds., Man and mining, studies in honour of Gerd Weisgerber on occasion of his 65th birthday, Deutsches Bergbau Museum, Bochum Martinon-Torres M. & Rehren Th., 2009, Post Medieval crucible Production and Distribution: A Study of Materials and Materialities, Archaeometry Vol.51 No.1 pp49–74 O. Faolain S., 2004, Bronze Artefact Production in Late Bronze Age Ireland: A Survey, British Archaeological Report, British Series 382, Archaeopress, Oxford Rehren, Th. and Papakhristu, O., 2000, Cutting Edge Technology – The Ferghana Process of Medieval crucible steel Smelting, Metalla, Bochum, 7(2) pp55–69 Rehren T. & Thornton C. P, 2009, A truly refractory crucible from fourth millennium Tepe Hissar, Northeast Iran, Journal of Archaeological Science, Vol. 36, pp2700–2712 Rehren Th., 1999, Small Size, Large Scale Roman brass Production in Germania Inferior, Journal of Archaeological Science, Vol. 26, pp 1083–1087 Rehren Th., 2003, Crucibles as Reaction Vessels in Ancient Metallurgy, Ed in P. Craddock & J. Lang, Mining and Metal Production Through the Ages, British Museum Press, London pp207–215 Roberts B. W., Thornton C. P. & Pigott V. C., 2009, Development of Metallurgy in Eurasia, Antiquity Vol. 83 pp 1012–1022 Scheel B., 1989, Egyptian Metalworking and Tools, Shire Egyptology, Bucks Vavelidis M. & Andreou S., 2003, Gold and Gold working in Later Bronze Age Northern Greece, Naturwissenschaften, Vol. 95, pp 361–366 Zwicker U., Greiner H., Hofmann K. & Reithinger M., 1985, Smelting, Refining and Alloying of copper and copper Alloys in Crucible Furnaces During Prehistoric up to Roman Times, P. Craddock & M. Hughes, Furnaces and Smelting Technology in Antiquity, British Museum, London