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342
LETTER II.
the Acid of Sulphur, Vitriol, or Alum; which are, indeed, the ſame with the former, and with each other, in different Combinations, can do it: And even no better a Menſtruum than common Water running over a Quantity of native Sal Armoniac, is able to produce from Copper, all the different Degrees of Blue, from that of the paleſt to that of deepeſt oriental Sapphires.
- I am,
- SIR,
- Your humble Servant,
- SIR,
John Hill.
GREEK
