Dictionarium polygraphicum. Zaffer.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol II.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
Zaffer; this is call'd in Latin Zaffira, which Merret tells us comes from Germany; it is taken by some for a preparation of an earth for tinging glass blue; others take it for a stone, and he himself for a secret, asserting that there are but few authors, who have made any mention of it, and no one that has told us what it is.

I shall here give you the sentiments of some authors, who speak of it, when the reader will see what authors are determined about it.

Cardan in his fifth book de subtilitate calls it a stone, his words are these; "there is another stone which colours glass blue, some call it zaffer."

Julius Scaliger, who has composed a treatise of glass, does not at all reprehend Cardan for calling it a stone. Cæsalpinus after Cardan, l. 2. c. 55. reckons it also amongst stones, thus he speaks of it: "there is another stone colouring glass blue, and if you add too much, it makes it black, they call zaffer; it inclines from an ash to a purple colour: it is heavy and brittle, and melts not of itself, but with glass runs like water."

Ferant. Imperatur, l.28. c. 8. says, that this stone is very like the load-stone and manganese; but the learned Agricola without doubt knew it not, for he makes no mention of it.

Anselmus Boetius of Boot, physician to the emperor Rodelphus II. who has giveq us a large history of all sorts of stones and jewels, has allotted no place to zaffer amongst those he mentions, altho' it be brought from Germany, according to the sentiment of Merret, who says zaffir is a compound, asserting it is neither earth nor stone, not mixing at all with water, nor breaking, as is easy to remark, by squeezing it between the fingers.

That certainly, if it were either of these two, it would have been discovered by the diligence of those that have treated of it, being of so great use to thole who make glass, which makes that author say, that zaffer is a secret, whereof the composition was found out by a German; that if he might give his conjecture of it, he should think it made of copper and sand, and some proportion of lapis calaminaris; that the blue colour it gives, seems to be owing to the brass, as that of manganese to iron. That only minerals can tinge glass, and that no materials can be found for that purpose, except metalline ones.

Wherefore he concludes, that the matter which composes zaffer can only be either copper or brass.


The method of preparing Zaffer for tinging Glass.

The only preparation of zaffer, according to Merret, is to grind it into a very small powder, and searce it through a fine sieve.

But Neri gives us one, which makes the glass much finer, which is this:

Take zaffer, in the biggest pieces you can get, put it into earthen pans, and let it stand one day in the furnace, then put it into an iron ladle to be heated red-hot in the furnace; take it thence, and sprinkle it with strong vinegar; being cool'd, grind it fine on a marble-stone, after which wash it with warm water in earthen pans, letting the zaffer settle to the bottom, and decanting off the water gently: this will separate the foulness and impurity from the zaffer, which will remain at the bottom pure and clean; which must be dry'd and ground again, and then kept in vessels close stopp'd for use.

This will tinge glass much better than the first.

Pomet, in his general history of drugs, makes mention of a mineral brought from Surat in the East-Indies, of a bluish colour, or like a partridge's eye, which he calls zafer, safre, or sapher, to which he ascribes the same virtue of tinging glass blue.