7 - A Salt that Will Make a Very Beautiful Crystal
Take lime salt [calcium oxide], which is used for building. Purify this salt and mix it with ordinary Levantine polverino salt in the proportion of 2 pounds per 100, which is 2 pounds of lime salt, to every 100 pounds of polverino salt, purified and well made, as previously described. With this salt mixture, you can make yourself ordinary frit, and put it in the crucible to clarify. I will refer to this frit from now on in the recipes for cristallino, crystal, and common glass. This way you will have crystal quite delightful and beautiful.