Be the first one to write a review. Three important schools among others developed: one emphasizing vitriol usually iron sulfate , another nitre saltpeter , and yet another mercury as the prime ingredient for the Great Work. The straight border between the layers are clear in the colour mapped cameo image from the cross-section sampled from the outside of the mantle. The catalogue includes three works of metal and one of morse ivory. Petersberg: Michael Imhof Verlag, , pp.
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