[157] Not really steel, of course, but a kind of speculum metal containing about one part of tin to two of copper. Fioravanti, in his Specchio di Scientia Universale, tells us that this acciaio was made of equal parts of brass and tin. He contrasts the German and Italian methods of preparation of glass mirrors, giving the preference to the former. Fioravanti then speaks of the interest taken in these mirrors—not by women only—and after balancing the pros and cons, he concludes that, on the whole—‘gli specchi son’ mala cosa nelle case.’
[158] A word that must not be confused with the term luse or lustro, applied by the Venetians to a mirror.
[159] There is a magnificent chandelier of this class in the drawing-room of Mr. Beaumont’s house in Piccadilly. It dates probably from the early years of the eighteenth century.
[160] ‘Notizia delle opere d’arte.’ I quote at second-hand, as I have not been able to find a copy of this work.
[161] The learned Cardanus, physician, mathematician, and astrologer, has a section on glass both in his De Subtilitate (1551) and in the somewhat later De Varietate Rerum. He is often quoted as an authority on the subject by contemporary and later writers, but in spite of many quaint and ingenious reflections I can find little of practical value in his remarks.
[162] Not to be confounded, says the writer, with the stone known as Magnese, found ‘nella Magna’ (Allemania or Germany). ‘Quite other are the virtues of this stone [magnetic oxide of iron?] when placed under your pillow, ...’ but for the context I must refer the reader to the sixty-ninth section of the original work.
[163] In the fourth section of the second treatise the author speaks of ‘azurro della Magna del quale si tinge il vetro.’ There is also a section at the end of the first book on the preparation of azurro fine from pietro d’azurro ultramarino, but I do not think that this has anything to do with the colouring of glass, as it is associated with recipes for dyeing grey hair of a blonde colour and for preparing the acqua virgine by which the face is rendered beautiful. It is difficult to understand what relation the Acqua di Philoseophy (sic—there are several sections so headed at the end of the treatise) has with the preparation of glass. But all these old formulists are only too ready to run off at a tangent to discuss questions of alchemy.
[164] In spite of what Milanesi says in his introduction, I strongly suspect this third treatise to be of a later date than the others; the whole tone of it seems to smack more of the cinquecento than of the previous century. At the same time it is inferior to the two preceding treatises in practical knowledge—indeed it contains much nonsense.
[165] See above, p. [174], for an account of L’Altare.
[166] But much the same might be said of the potter’s art; in this case, however, the artistic history is far more continuous and inter-connected than in the case of glass.