FOOTNOTES:
[5] See Tingry's Painter's and Varnisher's Guide. 1803.
[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.
[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.
"Ten grains of this soda were dissolved in 1000 grains of distilled water. But as 10 grains of this soda contained only 7.7 grains of anhydrous soda, the 1000 grains of water would contain just 0.770 per cent of soda—a quantity that differs very little from that contained in the saturated aqueous solution of borax.
"Seven measures of the soda solution were added to four measures of linseed oil. This mixture differed so little in appearance, that it might have been mistaken by any casual observer as identical with that produced by a similar proportion of the solution of borax. It had, however, a more soapy odour; and a considerable separation of its constituent parts occurred almost immediately after agitation. This separation increased for many days. The lower liquid was of a foxy brown colour, and, after a week's repose, it amounted to 38 parts out of 59. The upper 21 parts were white and saponaceous. I tried other proportions of soda solutions with oil, but none resembled the results obtained from solutions of borax with oil.
"Fancying that solutions of the bi-carbonate of soda might be more analogous to those of the bi-borate of soda in their effects upon oil, than solutions of caustic soda, I tried many mixtures of solutions of the bi-carbonate with oil; but they were all dissimilar, in appearance, odour, and properties, from like mixtures prepared with the bi-borate of soda."—Letter from C. Thornton Coathupe, Esq., on Vehicles for Pigments. Published in the Art Union of February 1832.
[8] We are greatly multiplying artists, by "the promise to the ear," and by our Art-Unions; whether we are like to have such returns to the Commissioners of the Income-tax as those we have quoted, as a consequence of our forced and hot-bed encouragement, remains to be seen. Lord Brougham objects to the railroad mania, on account of the beggary to be induced when the employment they give rise to is over. When the ferment of patronage shall again have settled down to a selection of a few favourites, may we not entertain somewhat similar fears?