Note 40 — LXXX. A Dissertation on the Antiquity of Glass in Windows. In a Letter to the Rev. Tho. Birch, D. D. Secret. R. S. By the Rev. John Nixon, M. A. F.R.S.
Reading edition
Pliny mentions a kind of glass or jet called obsidianum:—nigerrimi coloris, aliquando et translucidi, crassiore visu, atque in speculis parietum pro imagine umbras reddente. Nat. Hist. lib. xxxvi. c. 26. §. 67.
And that the practice of staining glass was known in his time, appears from what he says concerning the obsidianum mentioned above:—Fit et genere tincturæ—totum rubens vitrum, atque non translucidum. Ibid.