bone-ash cup
Học thuậtThân thiện
Definition
Noun: A bone-ash cup is a small, porous container or crucible made from bone ash (calcined animal bones). It is used primarily in assaying, the process of analyzing ores or alloys to determine their metal content. Its key function is to separate precious metals, such as gold and silver, from base metals like lead, through a process of cupellation where the porous material absorbs the oxidized base metals.
Usage
The term is used in the specific context of metallurgy and analytical chemistry. It refers to the physical tool used in a laboratory or assay office. * The assayer placed the sample in the bone-ash cup before heating it in the furnace. * For an accurate analysis, a clean bone-ash cup is essential to absorb the litharge (lead oxide).
Advanced Usage
- Historical Context: Bone-ash cups have been a standard tool in precious metal assaying for centuries due to the material's excellent porosity and refractory properties.
- Process Mention: The use of a bone-ash cup is central to the cupellation process, where the cup absorbs impurities, leaving a bead of precious metal.
Variants and Related Words
- Cupel: This is the more common general term for a small, porous cup used in assaying. A bone-ash cup is a type of cupel specifically made from bone ash.
- Assay Cup: A broader, functional synonym.
- Test Cup: Another general term for a cup used in testing metals.
Synonyms
- Cupel
- Assay Cup
- Test Cup
Related Phrases/Idioms
- To cupel: The verb form describing the action of using a cupel or bone-ash cup to refine or assay metals.
- The ore sample must be cupelled to determine its gold content.
Noun
- a small porous bowl made of bone ash used in assaying to separate precious metals from e.g. lead