Silver coin—pale gold color.
Pure silver—pale gold.
Silver coin—deep gold.
Pure silver—deep gold.
Silver coin—light blue.
Pure silver—light blue.
Silver chin—yellow.
Pure silver—blue, white, yellow not visible.
Silver coin—yellow, red at edges.
Pure silver—yellow, no red edges.
Silver coin—red, blue at edges.
Pure silver—yellow, no red apparent.
The intensity of the resistance offered by the different films of iodide of silver to a continuation of the chemical combination, may be determined by noting the moment at which the various spectral tints make their appearance.
| Color of the film of iodide of silver. | |
| ' | " |
| 0 | 50—beginning to darken. |
| 2 | 0—pale gold. |
| 4 | 40—deep gold. |
| 6 | 40—orange blue. |
| 7 | 30—blue. |
| 9 | 30—light blue. |
| 11 | 30—commencement of yellow. |
| 18 | 30—orange red. |
| 20 | 15—blue. |
| 22 | 55—deep blue. |
| 24 | 40—green. |
| 28 | 0—yellowish green. |
| 30 | 25—ruddy brown. |
| 40 | 10—green. |
| 46 | 30—green. |
| 50 | 10—red. |
| 53 | 15—green. |
By comparing the thickness of the colors with the space of time required for their production, it will be found, however imperfect the table given by Newton may be when applied to this subject, that towards the end of the experiment above given, the chemical combination is retarded by the presence of the inert film, and that to obtain the same thickness of film as at the commencement, about double the time is required.
The third cause of error may be avoided by operating with vapors of about the same force. In those described, the average time employed in passing to the maximum was generally about half an hour; if that were not taken into consideration, different results might be obtained.
In regard to chlorine, there exists another cause of complication—the affinity which it possesses for water; for when disengaged in the ordinary manner, chlorine carries with it a certain quantity of water which may very much alter the results of the experiment.—Philosophical Magazine, 1842.
[THE AMERICAN ELECTRIC TELEGRAPH.]
In each of the countries of Europe where the Electric Telegraph is established, viz.: Britain, France, Germany, and Russ a, the people seem anxious to claim for one or more of their own countrymen some merit in connection with the invention. The English speak of Wheatstone and Bain; the French of Le Sage; the Germans of Steinheil and Siemen; and the Russians of Schilling or Jacobi. Most of these inventors have their agents or representatives in different countries, ready on every suitable occasion to speak or write in behalf of their principal.
The inventor of the American Electric Telegraph has, we believe, no agent in Europe; and no person there who has any special interest in promoting the introduction of his system. The adoption of it by the Prussian government for great distances, as decidedly the best which it could obtain, after advertising extensively in Europe, is, therefore, the more remarkable; and especially, as the only knowledge which the Prussians possess of the American system seems to have been derived from one imperfectly acquainted with its powers; for we can account in no other way for the fact that Siemen's needle apparatus is adopted for short distances; Morse's instruments being clearly superior to Siemen's, or to any other needle apparatus, for short as Well as for long distances; since they are much more rapid in their motion, and have, besides, the advantage of making a permanent record on paper, instead of merely indicating to the eye by an evanescent sign. No one using the telegraph in America, would think of employing a needle apparatus in any of its operations.