Scientific American 27, 25.3.1848
On the substitute for white lead in painting which we gave a notice of in our last number, we have received the following report made at a late session of the Academy of Arts in Paris: -
In 1835 M. Leclaire, a house painter, having witnessed the ravages that white lead made among the workment engaged in his business, set himself to seek some white substance, which could take the place in the arts, of the poisonous article which had been heretofore used. After examined all the white substances which nature offers, he finally arrived at the white of zinc, and he discovered that this oxyde had all the qualities of the white of lead without having any of its inconveniences.
Whiter than the white lead, the oxyde of zinc reflects the light instead of absorbing it, gives a finer tone, and covers better the surface on which it is spread. Moreover it is not subjected to any of the action of the sulphurs, which blacken so quickly paintings in white lead. Finally, and it is the capital point, the preparation and use of it do not in any way affect the health of the workmen.
After having assured himself that the mechanical preparations of the white of zinc might be realized in an economical manner, M. Leclaire was desirous to complete his invention by replacing, on the painter's pallet, all the color of which lead makes a part, by other articles of which zinc will be the basis. In this difficult enterprise, he has had, as far as we can now judge, the most complete success, and the inventor of white zinc has filled up the gamut of unchangeable colors by the substition of stable and inoffensive colors for those which have copper and lead for the basis. He has even succeeded in replacing the driers, of which litharge always forms a part, by a substance the properties of which are equal to it, and which only contains manganese.
The harmlessness of all these substances seems to be demonstrated, now, by decisive experiments. M. Leclaire employes constantly in all the different quarters of Paris, two hundred workmen, in the application of his colors. Among them are several who had been compelled to leave off their trade in consequence of suffering from the painter's colic. None of them have felt the least inconvenience from the use of the new substances. - The workmen employed in the manufacture of the zinc white, have also presented none of the phenomena of intoxication, notwithstanding the imperfections which necessarily result from a temporary arrangement.
As to the superiority of the new colors in reference to their stability, the experiments presented by M. Arago leave no doubt in this respect. It is enough to quote one. - After having covered the two halves of a board, one with the colors of M. Leclaire, the other with those which are still used by painters, the surface was exposed to the uniform action of a current of sulphuric hydrogen. The first half preserved all its treshness, while the second immediately turned black. If this durability of the colors prepared by M. Leclaire does not make the greatest merit of his invention, it may, nevertheless, be considered as a very important circumstance. What is there in fact more precious to preserve, after the life of man, than that of the works to which genius has given birth, and it is not a valuable present to make our painters, that of placing on their pallets, colors that time cannot change.
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