The Year-Book of Facts in Science and Art
Exhibiting the Most Important discoveries and Improvements of the past year,
in mechanics and the useful arts; natural philosophy; electricity; chemistry; zoology and biology; geology and geography; meteorology and astronomy.
By John Timbs,
editor of "the Arcana of Science and Art."
London:
David Bogue, Fleet Street,
MDCCCXLIX (1849)M. Leclaire, house-painter, of Edinburgh, calls attention to a substitution which he daily makes of the white of zinc, and colours with a zinc base, for white lead and colours with a base of copper and lead, in the arts and for ordinary purposes.
In his practice, M. Leclaire employs the white of zinc, which appears to possess all the qualities of white lead, without any of its inconveniences. Thus, if we must give credit to his statements, and the results are of sufficient standing to render it easy to verify them, zinc-white is much whiter than white lead; ground and used with oil, it reflects the light, instead of absorbing it; it furnishes finer and more transparent tones, it covers better, and with equal weights, a larger space; it remains unchanged by sulphurous fumes, which immediately blacken objects painted with lead; finally, the manufacture and use of zinc-white has no injurious effect upon the health. But all this is not sufficient for the complete solution of the problem. In fact, although zinc-white was known in science, it has never been collected hitherto but as a produce of the laboratory. It was ne-cessary to obtain it in quantities, and at an accessible price. Then, once obtained and mixed with oil, it was necessary, in order to apply it readily to painting, that it should be made to dry easily. Now, the only drying substances we knew had a leaden base, and thus communicated all the defects of lead to the zinc-white. M. Leclaire has obtained a drying substance with a manganese base, which has the property of drying zinc-white more readily than litharge could do.
This was not all. White tones form, so to speak, a kind of exception in painting. Some of the colours most in use are extracted from lead and copper, and owe to these metals the defect of being alterable by sulphurous gases: mingled with zinc-white, they deprived it of the advantage of being unalterable. It was necessary, therefore, to render the process complete, and its application common, to substitute colours which undergo no change for all these alterable colours. "After many years of research," says M. Leclaire, "I have succeeded in producing, if I way use such an expression, the commencement of a reformation in painting, by completing the scale of unalterable colours, — by the substitution of inoffensive and unalterable colours for all such as had lead or copper for their base; so that I can now affirm, 1st, That the health of a great number of men may be saved without any detriment to the profession; 2dly, That the interior and exterior of houses may be painted without the least risk of the colours changing or blackening by sulphurous emanations; 3dly, That pictures will be no longer liable to change their appearance and harmony with the lapse of time, as has happened with so many pictures of the old masters."
M. Leclaire constantly employs about two hundred workmen in Paris. From the time that he substituted zinc-white for white-lead, not only has he never had a case of lead-colic, but he affirms that no indisposition has at any time appeared among his workmen which can be attributed to their profession. The work has been entrusted to the examination of a commission.
— From L’Institut, No. 734; Jameson's Journal, No. 88.
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