25 de Maio
THE LITERARY GAZETTE AND JOURNAL OF BELLES LETTRES, ARTS, SCIENCES
London, Saturday, may, 25, 1839
An omission was made in the paper on Photogenic Drawing, which was inserted in the last Number of the Literary Gazette; for, whilst treating of the ammonio-nitrate of silver, I forgot to mention the proportions which were found most suitable: this may seem unimportant in a paper which is not very sensitive, but, as the case and ertainty of its preparation, as well as its cheapness, exceed all other described papers, it possesses a particular claim for our notice. Twenty grains of nitrate of silver are to be dissolved in an ounce of water; then a few drops of ammonia are to be added, which at first throws down a considerable precipitate; this, by a further addition of ammonia, redissolves, and the solution becomes quite clear, when it will be ready to be applied by a sponge to the paper. The most suitable paper for this preparation of silver is the “double copy” . The whole cost of photogenic paper does not exceed, by this process, one penny for a sheet equal in size to large foolscape, which, if bought of venders, would cost between one shilling and four pence and four shillings. The cost of all others papers does not exceed two pence-half-penny the sheet, except that prepared with the bromide of potassium; which, for the same quantity, would be about one penny more expensive. The preparation of paper suitable to the use of the corrosive sublimate is still more simple, for here it is only necessery to sponge over a very thin paper with 20 gr. solution of nitrate of silver, and expose it to the action of the light of the sun. Drawings made in this way have analogy with etchings executed on glass, covered with black varnish, but are more easily made; the white parts of the paper are, however, not so transparent as the glass. An error requiring notice has also crept into my paper; for the hyposulphates, instead of the hyposulphites, are there mentioned as stopping agents.
Bank of England, May 21st, 1839.
quarta-feira, 7 de julho de 2010
1839, 25 de Maio - THE LITERARY GAZETTE AND JOURNAL OF BELLES LETTRES, ARTS, SCIENCES
Etiquetas: 1839, Alfred Smee, Literary Gazette and Journal of the Belles Lettres Arts Sciences etc (The)