[26] An excellent example of this type of line is seen in the horizon lines on the left, which in this case were added only after several proofs had been pulled from the plate. The addition of these lines constitutes the difference between the recorded first and second states of this print.
[27] The documents on this story were first published by Bredius in 1909 ("Rembrandt als Plaatsnijder," _Oud-Holland_, v. 27, pp. 112 f.) and have been frequently cited since then. The print is the portrait of Jan Antonides van der Linden (Hind 268).
[28] Confusion has arisen over a note, clearly in Rembrandt's hand, on one of his drawings (Benesch 1351, Hofstede de Groot 763, dated about 1654-55). The Dutch text is given in +Benesch+, op. cit., vol. 6, p. 374. It reads, "In order to etch ...," and gives a recipe consisting of turpentine and turpentine oil. This, of course, could not possibly be a mordant. Münz discusses it (op. cit., vol. 2, p. 14) and concludes that with the addition of mastic, this could be a kind of stop-out varnish. We are not likely to come closer to an answer for this cryptic inscription.
[30] _Ibid._, p. 117. Detail of plate for Hind 277, dated 1654.
[31] +Bosse+, op. cit., pp. 5 and 11. Vitriol is copper or iron sulfate, saltpeter is potassium nitrate, and alum is an aluminum sulfate salt. Bosse's other two acids are distilled pure vinegar (acetic acid) and a boiled mixture of vinegar and chloride salts. Both are relatively weak. My thanks to Dr. Robert P. Multhauf for his advice on 17th-century chemistry.
[32] +Felix Brunner+ (_A Handbook of Graphic Reproduction Processes_, New York: Hastings House, 1962, p. 124), suggests that Rembrandt may have used ferric chloride, a weaker mordant, around 1640.
[33] +Rosenberg+, _Rembrandt: Life and Work_ (London: Phaidon Press, rev. ed., 1964), p. 330.
[34] My gratitude to Jacob Kainen for first pointing out the existence of these disembodied spirits.
[35] Arnold Houbraken, quoted in +Hofstede de Groot+, _Die Urkunden_ ..., op. cit., no. 407, p. 471.
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