[Footnote 5: See TINGRY'S _Painter's and Varnisher's Guide_. 1803.]
[Footnote 6: 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.]
[Footnote 7: "As the very peculiar property which a saturated solution of borax possesses, of uniting so readily with oil in any proportions, has never yet been noticed by chemical writers, I experimented with its constituents, boracic acid and soda, separately, with a view to determine whether the results were to be attributed to the acid, to the alkaline base, or to the particular salt formed by their union.
"One hundred parts of borax may be said to consist of:--
Parts Boracic Acid, 35.80 Soda, 16.85 Water, 47.35
Consequently, 24 fluid ounces of water, holding in solution 1 ounce (avoirdupois) of borax, will contain about 4.16 per cent of borax, or 0.702 per cent of soda only.
"I first tried the effect of a saturated aqueous solution of boracic acid with linseed oil. They would not unite. I then prepared some caustic soda by boiling a solution of carbonate of soda with quicklime, decanting the clear caustic liquor, evaporating in a silver crucible, re-dissolving in alcohol, and then distilling the spirit, and heating the residual pure soda to redness. Even in this state, soda contains 23 per cent of water, and only 77 per cent of _pure anhydrous soda_.