A process for extracting from their sulphides zinc and lead and generally all metals whose affinity for sulphur is inferior to that of copper

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Listed from its IP Australia record in Patent Yard's archive of Australian patents past their term. Its claims, description and drawings are in the AusPat record and on Google Patents, and the Claude kit works from them.

Why it's free to use

• Filed June 20, 1904. Even if it was granted, its term would have ended by June 20, 1925.
• A pharmaceutical extension adds at most five years, so even that would have ended by June 20, 1930.
• We check Australian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.