What is a sulphide, analogous to a sesquioxide, containing three atoms of sulphur to two of the other ingredient; -- formerly called also sesquisulphuret; as, orpiment, As2S3 is arsenic sesquisulphide called?

sesquisulphide — A sulphide, analogous to a sesquioxide, containing three atoms of sulphur to two of the other ingredient; -- formerly called also sesquisulphuret; as, orpiment, As2S3 is arsenic sesquisulphide. (Webster's 1913.)

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