It must be further observed that the color of the impression of the five cents varies greatly from the original pale red brown, called bronze. Many shades of faint red brown, red brown, faint dark brown, deep dark brown, black brown, bluish black, and almost pure black, may be found. Whether these result, as seems to be the case, from a natural change in the course of time, from something in the ink, paper or surroundings of the stamp itself, or whether it results from the use of different colored ink originally, may perhaps be impossible now to determine.
The ten cent, however, varies very little in the color of the impression. Beyond a lighter, or grayish shade, a black with a bluish cast, and the ordinary black impression, little is to be noticed.
The stamps are separated in the sheet by about 2 mm., each way. Double copies of the five cents, adhering either by the side, or by the top and bottom, are often found on old letters, and occasionally, three or four adhering specimens are encountered. The ten cents is almost invariably found in single specimens, though a few pairs, and even three used together are known.
According to a statement in the American Journal of Philately, of April, 1871, this issue was withdrawn from circulation between June 11th and September 30th, 1851. The instructions of the Department to the deputy postmasters, concerning the distribution of the next issue, published in June, 1851, order that these five and ten cent stamps must not be recognized as prepaying letters after the 30th of June, 1851, and request the public to return them to the deputy postmasters, in exchange for others of the new issue. The report of the Postmaster General for the year expiring June 30th, 1851, and published in the fall of that year, further states: "Directions for the destruction of the dies and plates, employed in the manufacture of the stamps formerly used, have been given, and for counting and burning such stamps as have not been issued to postmasters or have been returned."
These facts probably explain the extreme rarity of unused stamps of this issue, and the re-engraving of the dies by the Government, when it was considered advisable to make an exhibit of all its issues of adhesive stamps at the Centennial Exhibition.