British opium. : The Society have for some years offered premiums to encourage the cultivation of the white poppy in this country, ...

Date:
1825
Catalogue details

Licence: Public Domain Mark

Credit: British opium. : The Society have for some years offered premiums to encourage the cultivation of the white poppy in this country, ... Source: Wellcome Collection.

    1/4 (page 55)
    y/' €*/ y U 3 - M 4 S CHEMISTRY. 55 He covers the ornament, and all those parts that are not to he corroded, with a composition that will resist water. W ax, dissolved in spirits of turpentine, and mixed with white lead, may be used with a camel-hair pencil; or turpentine varnish, with a little animal oil and white lead, and will be found to work more freely than the w ax. Spirits of turpen¬ tine must be used in pencilling with these campositions. The use of animal oil is to prevent the varnish from becoming very hard, which would render its removal, after corro¬ sion, extremely difficult. The ornament, and other parts which are intended to be preserved, being completely co¬ vered with the composition, it is suffered to remain a few hours to dry. The article is then put into a vessel of rain w ater, in which it must remain forty-eight hours, or longer, according as the ornament may be required to have more or less relief. When the corrosion is completed, the varnish or w ax must be removed w ith spirits of turpentine, which may be applied w ith a bit of sponge, and then be wiped ofT with soft rags. The article, being made quite clean, is now rubbed over with a soft brush, dipped into finely-powdered plaster of Paris, and is applied in the dry state. This powder tills the pores of the corroded parts, giving a certain degree of opacity, similar to that which is left from the tools of the sculptor. It forms a good ground that contrasts well with the ornament, and makes it appear w ith greater advantage than if left merely in the corroded state. The alabaster of which the vase is made was procured from a quarry at Chellaston, about four miles from Derby.