"C3", "A. dipt H-H Co, Prussic Acid" in J.B. Bacon's handwriting; the impression and surrounding area somewhat degraded by the chemicals and strengthened on reverse with hinges. S.G. Spec. DP20F. Photo in colour" /> Proof First Trial Plate, portion of the sheet showing one impression in dark blue on wove paper without watermark, handstamped "No.712" in black and chemically treated in an attempt at removal, inscribed<I> "C3"</I>,<I> "A. dipt H-H Co, Prussic Acid"</I> in J.B. Bacon's handwriting; the impression and surrounding area somewhat degraded by the chemicals and strengthened on reverse with hinges. S.G. Spec. DP20F. Photo in colour | Christie's