US5171A - Improvement in photographic pictures - Google Patents

Description

U ITED STATES- PATENT; .OFFICE.

WM. HENRY Fox TALBOT, 0F ao 00K ABBEYKENGLAND/ IMPROVEMENT IN PH oToe-RAP Ic Pic-runes.-

Spccification forming part of Letters Patent No. 5, 171, dated June 26, 1847.

30 all'whom'itmay concern: 4 Be it known thatI, WILLIAM HENRY Fox TALBOT, of Lacock Abbey, in the county of Wilts, 'esquire, a subject of the Queen of Great Britain, have invented or discovered certain new and useful Methods of Making Photo graphicPictures and Portraits; to which I have given the name of Galotype or Talbotypc pictures,which termsmustbeunderstoodashaving the same import- -asin the'present specification I employ the latter one; and -I,'the said WILLIAM HENRY Fox Tumor, do hereby declare that the nature of my said invention and the manner in which the same is to be performed arefully described and. ascertainedv in and by the following statement -thereof--that isto say-f The first part of my invention is a method of making paper extremely sensitive to the rays of light. For this purpose I select the a mark upon that side by which to know it again. I dry the paper cautiously at a distant fire; or else Ileave it to dry spontaneously in a dark place. Next I dip the paper in a solution of iodide of potassium containing vfive hundred grains of that salt dissolved in one pint of 'water. I leave the paper a minute or two in this solution. I then take it out and dip it in water. I then dry it lightly with blottingpaper and finish drying it at a fire, or else I leave it to dry spontaneously. The paper thus far prepared may be called, for the sake of distinction, iodized paper. When well made it is quite insensible to the action of light, and

will. keep for many years without suflering any change. 7 Second part of the, preparation of the paper.- This second partis bestdeferred until the paper is wanted for, use. .When that time is ar-- rived I take a sheet .of the iodized paper and wash it with a liquid prepared in the follow-' ing manner: Dissolve. one hundred grains of crystallized nitrate of silver in two ounces of distilled water. To this solution add one-sixth of its volume of strong acetic acid. Let-this mixture be called A. Dissolve crystallized gallic acid in distilled water,asmuch"as it will dissolve, (which is a very small quantity.)- Let This operation should be'perfornied bycandlelight. Let the paper rest half a minute, and then dry it lightly with blottin g-paper. When nearly or quite dry the paper is fit for use but it is advisable to use it within a short time af- 1 ter'its preparation.

formed in the focus of the lens. Of course the paper must be screened or defended from the light during the time it is being put into the camera; When the" camera is properly pointed at the object this screen is withdrawn, or a pair of internal folding doors are opened, so as-to expose the paper for the reception of the image. If the object is very bright or the time employed is sufliciently long, a sensible image is perceived upon the paper when it is withdrawn from the camera; but when the time is short or .the objects dim no image whatever is visible upon the paper, which appears en tirely blank. Nevertheless it is impressed with an invisible image, andI have discovered the means of causing this image to become visible. This is performed as follows I take some gallo-nitrate of silver, prepared in the manner before directed, and. with this liquid I wash the paper all over-with a soft camels-hair brush.' I then hold it before a gentle fireand in a short time, varying from, a few seconds to a minute or two, the Image begins to appear upon-the paper. Thosepartsof the paper upon which light has'acted the most strongly become brown or-black, while those parts on which light has not acted remain white. The image continues to strengthen and-grow. more and more visible during some time. When it appears strongenongh the operation should be terminated and the picture fixed.

Use of the paper.-.-The paper thus prepared, and which [call Talbotype paper, is placed v in a camera obscura so as toreceive-the image;

its lights andshades reversed with respect to the natural objectsvidelicit, the lights of the objects are represented byshades, and vice verse-for which reason I call it a negative? picture. But it is easy from this negative pictureto obtain another. which shall be positive Or conformable to nature-videlit'ait, a picture in whichlights shall be represented by lights 7 and the shades by shades. it is only necessary for this purpose to take a second'sheet oi the same sensitive paper and place it in close contact with the first upon which the picture has been formed. A b ard is put beneath them and a sheet of glass above, and thewhole is pressed into close contact by screws. Being then placed in sunshine or daylight for a short tin c an image or copy is formed upon the second sheet of paper. 1 This'iuiage or copy is often invisible at first: but the image may he made to appear in the same way that has been already stated; but I do not recommend that the copy should be taken on this kind of sensitive paper. 011, the. contrary I would advise that it should be taken on common photographic paper. This paperis made. by washing, good writing-paper first with a weak solution of common salt, and next with a solution of nitrate of silverbut since it is well known, having been freely communicated to the public by myself in the year one thousand eight hundred and thirty-nine, and that it forms. no'

part of the present invention, I need not desciibeit here more particularly. Although it takes a much longer time to obtain a copy upon this paper, yet the tints of the copy are generally more harmonious and agreeable. In order to fix such positive copies I recommend to dip them into three separate vessels of warm water, then into acold solution ofhyposulphite of soda, and lastly to dip them once more into three separate vessels of warm water. r The following may be considered as auxiliar'y and additional modifications of my discovery or invention: I sometimes take asheet of iodized paper and wash it over with a solution of gallic acid in water and then'dry it. Paper so prepared I call iogalli'c paper. It will remain good a considerable time if "kept in a press or portfolio. When wanted'for use I wash it with a solution of nitrate of silver, which renders it sensitive to light and fit to housed in the camera. "This. process difi'ers from the talbotype process, before described by me, in not'using the'nitrate of silver and gallic'acid in. conjunction. I find it is advantageous to use them separately on many occasions. because it removes the great iuconveni ence arising from the speedydecomposition of gallo-nitrato of silver. Since the yellowish" .tint-of sometalbo'type negative pictures 1mpedes the 'process'ot' taking copies from them,

in order to remedy this defect Iv plunge the picture into a hot bathpf hyposnlphite of soda, (or any other soluble hyposulph1te,) d1ssolved in about ten times its. weight of water. This solutionshould be heated to nearly the boiling-point. .The picture should remain in it about ten minutes. It is thenremoved, washed, and dried. By this process the picture is rendered more transparent and its lights become whiter. It is'also rendered exceedingly permanent. After this process I sometimes wa'x the picture by causing melted 'wax to penetrate into the pores of thepaper, the object of which is to give increased transparency.

In the above-described process I claim as of my own invention and discovery- 1. The preparation of iodized paper, as above described, whit-h is not itself sensitive to light, but serves as'the basis of all the subsequent operations.

2. The employmentof gallic acid, in conjunction with iodine and the salts of silver, to render paper extremely'sensitive to light, the gallic acid not having been used in photography previously to my discovery.

3. It was not known previous to my discovery thereof that paper could be impressed with a latent or invisible photographic image. I claim this as my own discovery and likewise the means of rendering the image visible at pleasure-namely, by washing the paper in the manner before described with gallo-nitrate of silver or with any other chemical liquids which act upon those parts of the paper only which have been previovsly acted upon byligbt.

4. The using hot or boiling solutions of the hyposu-lphites in order to give increased whitenessto talbotypep'hotographic pictures andat the same time make them exceedingly permanent.

5. The waxing talbotype negative pictures. in order to make them transparent, and thus .to'facilitate the obtaining positivecopies-theree from, the said pictures having been previously whitened by immersion in the hot solution of hyposulphite, as last mentioned.

W. H. F. TALBOT. Witnesses;

J os. MARQUETTE, "W. H. RITGHIE.