US 516859 A
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(No Model.) I v Y W. R. DALES. SAFETY ENVELOPE.
No. 516,859; Patented Mar. 20, 1894.
WITNEEEEE I INVENTD;
Ni'rn \VILLIAM R. DALES, OF ST. PAUL, MINNESOTA.
SPECIFICATION forming part of Letters Patent No. 516,859, dated March 20, 1894.
Application filed February 8, 1893. Serialll'o.461,450. (No model.)
and has for its object the provision of novel,-
simple and efficient means for preventing the opening of such envelopes without injury 7 thereto, and the fact of such opening having been attempted concealed. As is well known, the opening of envelopes through the application of heat or moisture and the softening of the gum thereof, also, by the insertion of a suitable instrument, for instance, a pen-holder or pencil, beneath theirflaps, is quite a simple matter and leaves the envelope uninjured and unmarked in any way and in such condition that it can be readily sealed up again, without subsequent detection. I Even wax sealing has proven ineffective, as the melting of the wax and the rescaling of the envelope thereafter,through the medium of a duplicate seal, has been found comparatively easy.
'My invention consists of a safety envelope provided with registering slits or openings in its side and bottom flaps, having its upper or sealing flap provided with an extension or tongue of sufficient length to permit of its being folded or doubled and gummed on one side when so folded. Between the folds of which is placed a quantity of a fusible substance or compound. Said tongue or extension, after having its gummed side moistened, being adaptedfor insertion through the slits or openings aforesaid and to be bent upwardly inside the envelope. Bringing such,
gummed side next the bottom and side flaps, to which it adheres under pressure. Preventing access to said tongue by an opening instrument of any kind, While. the application of heat to the envelope, for softening the gum which secures its parts together, will cause the fusible substance or compound to melt' and spread over or saturate the envelope. Producing ineffaceable evidence of the fact that the opening of such envelope has been attempted.
ope-blank provided with the top and bottom flaps B Band theside flapsOO', all gummed, as usual, the latter having a portion only of their opposite edges overlapped, forming the lips c c, the outermost of which being also gummed to permit of its being secured to the other one, the remainder of such edges simply meeting without overlapping, as shown at 0 Said lips have each therein horizontal slits or openings 0 c of like extent, as has, also, the lower flap B, as shown at b, said slits or'openings all registering when the flaps in which they are located are placed and secured by the gum'thereon in the relation shown in Fig. 2. The flap B of the envelope is provided with an extension or tongue I), having its underside, 19 when folded as in Fig, 2, gummed. Said tongue being of such width as to permit of its being passed through the slits or openings mentioned,1after the gum thereof is moistened, and thrust upwardly in side the envelope, in which position, when sufficiently pressed, it adheres equally to the side flaps, at each side of thejunction of their meeting edges. Said tongue, in its passage through the openings, preventing the drawing out of the side and bottom flaps, upon'the softening of the gum which secures them together, while the adherence of the same to the inner surfaces of said side flaps, prevents the drawing out of the tongue from this position, where it cannot be reached by any outside agency for the purpose of separating it der, for the purpose of drawing it out, will result in the destruction of said tongue. Now, in order to guard against the undetected opening of the envelope through the application of heat and the consequent softening of the gum thereof, the tongue I) is of such length as to permit of its being first turned upon itself, or doubled, as shown in Figs. 2 and 4, forming a pocket for retention of a suitable fusible substance, as pal-affine, upon the inner side of one of the folds which form such pocket is run a. narrow line of such substance, which latter serves to unite the folds of and stiffen the tongue, at the same time is concealed therein and, upon the application of heat thereto, spreads over and saturates the envelope and causes its discoloration, the latter result being more effectively attained through the combination, with the fusible substance, of a coloring matter. So that my invention, while preventing the opening of envelopes without their destruction, renders the fact of the envelopes having been tampered with perfectly apparent, the knowledge of which operating as a warning to a party of wrong intentions.
That I claim as my invention is as follows:
In a safety envelope having registering slits or openings in its side and bottom flaps, the combination of the sealing flap provided with an elongated transversely folded or doubled tongue, one side of which has an adhesive surface, and a fusible substance or compound secured between the folds of said tongue, the latter beingadapted forinsertion through said slits or openings and for adherence equally to the inside of both said side flaps, substantially as specified.
In testimony whereof I have hereunto set my hand this 4th day of February, A. D. 1893.
\VILLIAM R. DALES.
WM. H. POWELL, R. DALE SPARHAWK.