What is of, pertaining to, or designating, a hypothetical sulphacid (called also thioarsenious acid) analogous to arsenious acid, and known only in its salts called?

sulpharsenious — Of, pertaining to, or designating, a hypothetical sulphacid (called also thioarsenious acid) analogous to arsenious acid, and known only in its salts. (Webster's 1913.)

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