Note 6 — CENNINO CENNINI ON PAINTING.

Take two pounds two ounces and a half of borax, and one pound of acetate of lead, dissolve each in at least a pint of hot water, mix together the two solutions, and allow the precipitate to subside. Pour off the supernatant liquor as soon as it is clear, add some fresh water (rain water is preferable) to the precipitate, and agitate. Then pour the precipitate, whilst it is distributed throughout this last addition of water, upon a filter of white blotting paper, and when the water has passed through the filter, add more water. These fresh additions of water must be repeated three or four times, merely for the purpose of washing away all traces of the liquor which was retained by the first precipitate, and which was formed by the first admixture of the two solutions. The precipitate, when well washed, is to be placed in a Hessian crucible, and exposed to a red heat for half an hour. A clear glass will be formed; which must be reduced to a very fine powder.