Complex sentence: It is likely he had appointed Johann Heinrich Gottlob Justi to improve the recollection of silver and cop-per from debased coins through cupellation; his furnace in Retwisch was taken over by Veitel Heine Ephraim.
Split into simpler sentences: It is likely he had appointed Johann Heinrich Gottlob Justi to improve the refining of silver and copper from debased coins through cupellation. His furnace in Retwisch was taken over by Veitel Heine Ephraim.