Relating to or containing sulfur compounds; characteristic of alum or sulfuric compounds in chemistry.
Possibly from Greek altheios or related to althea, but more likely from a technical chemical term. The -ic suffix makes it an adjective describing chemical properties or compounds.
This appears in old chemistry texts but is extremely rare today—it's a 'ghost word' that shows how scientific terminology evolves and some perfectly logical terms simply get replaced by newer, clearer names.
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