Coloring Back Grounds--Transparent ditto--Gilding Dissolvent Solution for removing Specks--Solarized Impression--To Purify Water--Cleaning Mercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax for Bottles--Rouge--Rotten Stone--Potassa Solution--Hyposulphite Solution--Substitute for do.--Gilding Solution--Solution for increasing the Brilliancy of the Daguerreotype--Bleaching Solution;--Cold Gilding--Neutralizing Agents--Buff Dryer--Keeping Buffs in order--Cleaning Buckskins--Reflector for taking Views.

To Color Back-grounds--To obtain a properly colored back ground is a matter of no little importance to the Daguerreotype operator. I had nearly exhausted all patience, and tried the skill of painters to obtain a back-ground that would be suitable to my purpose; but all to no avail. At last I adopted the following method, and at a cost of coloring of twenty-five cents, can now produce a back-ground far more valuable than those which had cost five dollars before.

Take common earth paint, such as is used in painting roofs; mix this with water to about the consistency of cream; then to four quarts of this mixture add about one pint of glue water (common glue dissolved in water, also about as thick as cream). This last will cause the paint to adhere to the cloth, to which it is applied with a common white-wash brush. By applying the brush on the coating while it is wet, it may be so blended that not a line can be seen, and a perfectly smooth color of any shade can be obtained. The shade of color I use is a light reddish-brown. Tripoli, rotten-stone, or any earthy matter, may be applied in the same manner.

Transparent or Invisible Back-ground.--I give this as originally published in my System of Photography, 1849:

"Take a large woollen blanket with long nap, the longer and rougher it is the finer will be the effect produced; stretch it on a frame of sufficient size, and suspend the frame at the centre of the upper end by a string fastened to a nail in the ceiling, from three to five feet back of the sitter. Having arranged this, fasten another string to the side of the frame, and while the operation is going on in the camera, swing the back-ground from right to left, continuing this during the whole time of sitting, and you have a clear "transparent" back-ground, which throws the image out in bold relief, and renders the surface of the plate invisible. If equalled at all it is only by atmospheric back-ground. I consider it to be the best ever known, and think it needs but to be tried to afford satisfactory proof that it is so. Although used by few before, since the first edition of this work at least two thirds of the operators have adopted its use; for any one can at once understand the principle and the effect which it produces."

It may be added that a motion imparted to to any back-ground where softness is desired, produces an excellent effect.

Gilding Dissolvent.--To one quart of muriatic acid add as much oxide of iron (common iron rust) as it will dissolve in two days. This may be done by putting in the oxide in excess. It should be frequently shook, and when wanted for bottling it should be allowed to stand in order to settle. When this is done the solution may be poured off, and reduced by adding to it an equal quantity of water; then it is ready for use. This constitutes a gilding dissolvent now in our market.

Solution for Removing Specks.--There is probably no one cause of complaint so general as "what makes those black specks?" There are several causes which produce them, and probably the most general are dust, rouge, or a spray of moisture on the plate. It this be the case, there is no solution which can remove them, as they have prevented a chemical action with the silver, and their removal would only expose the surface of the plate which in itself would afford a contrast with the impression. Another and less dangerous source of these specks is organic matter contained in the solution employed in dissolving the chemicals, or the water in washing. Much of the hyposulphite of soda in market contains a sulphuret, which, coming in contact with the silver surface, immediately causes oxidation. Such spots, as well also as most all others found on the plate after it has been exposed in the camera, can be removed by the following, solution: To one ounce of water add a piece of cyanide of potassium the size of a pea; filter the solution and apply by pouring it on the surface of the plate. In all cases the plate should first be wet with water. Apply a gentle heat, and soon the spots disappear, leaving the impression clear and free from all organic matter.

In the absence of cyanide of potassium, a solution of pure hyposulphite of soda will answer as a fair substitute.

To Redeem, a Solarized Impression.--The Daguerreotype plate, prepared in the ordinary manner, should be exposed in the camera a sufficient time to solarize the impression. Then, before it be exposed to the vapor of mercury, expose it for a very brief period to the vapor of either chlorine, bromine or iodine. Then expose over mercury, as usual. I have produced singularly interesting results by this process.

To Purify Water.--Filter the water well, and then add about three drops of nitric acid to the pint. This can be used as absolutely pure water, but I would recommend the use of distilled water as preferable.

Cleaning Mercury.--Make a small bag of chamois skin, pour in the mercury, and squeeze it through the leather. Repeat this several times, and filter by means of a funnel made of paper, with a very small aperture, through which it will escape and leave the particles of dust, or other substances, in the paper. A paper with a pinhole through it will answer as well, and it is less difficult to make.

Adhesive Paper.--Take gum arabic, four ounces, put it in a wide-mouthed bottle and pour on water about one-third above the gum. Add half ounce of isinglass, or fish glue, and a small piece of loaf sugar. Let all dissolve, and spread over French letter paper, with a brush or piece of sponge. If once spreading is not enough, perform the same operation a second time.

Black Stain for Apparatus.--Dissolve gum shellac in alcohol, or procure shellac varnish at the druggists', stir in lampblack, and apply with a sponge or bit of rag. This will adhere to metal, as well as wood, and is used for the inside of camera, tubes, etc.

Sealing Wax for Bottles.--Melt together six parts rosin and one beeswax, and add a small quantity of lampblack; or, if red is preferable, add red lead. Common white wax is best, as most chemicals act less upon it.

When bottles containing bromine are to be sealed, it is well to grease the stopper. This, however, only when the bottle is in frequent use, for if it were to be sent by any conveyance it would be likely to fly out.

Rouge.--The method employed by Lord Ross is probably unsurpassed in the production of rouge. He has given his process as follows:

"I prepare the peroxide of iron by precipitation with water of ammonia, from a pure dilute solution of sulphate of iron; the precipitate is washed, pressed in a screw press till nearly dry, and exposed to a heat which in the dark appears a dull, low red. The only points of importance are, that the sulphate of iron should be pure, that the water of ammonia should be decidedly in excess, and that the heat should not exceed that I have described. The color will be a bright crimson inclining to yellow. I have tried both potash and soda, pure, instead of water of ammonia, but after washing with some degree of care, a trace of the alkali still remained, and the peroxide was of an ochrey color, till overheated, and did not polish properly."

Care should be observed to apply rouge in a dry state to the surface of the plate.

I would remark, that so far as my experience has gone, I consider good rouge fully equal to any other polishing, material for the last or finishing polishing; consequently I shall not take up my space in enumerating any of the great variety that find few advocates.

Why Rouge is to be preferred.--"Because it burnishes better, and because it assists in fixing the layer of gold, rendering it less susceptible of being removed in scales when heated too much."

Rotten Stone.--"Purchase the best ground rotten stone of the druggist, put a few ounces at a time in a wedgewood or porcelain mortar, with plenty of clean rain water. This should have about forty drops of nitric acid to the quart. Grind well, and after letting the mortar stand two minutes, pour into a third. After remaining undisturbed eight minutes, finally pour off into a fourth to settle. Rinse back the sediment in the second and third, and grind over with a new batch. Repeat the operation till you have all in the fourth vessel. Let this stand several hours, and pour off the water very carefully. Set the deposit in the sun, or by a stove to dry. When perfectly dry, pulverize, and it is ready for use. With a little trouble you will obtain in this way a much better article than can generally be bought of dealers. For the last washing, alcohol, or a mixture of alcohol and water, is preferable."

Potassa Solution.--The use of a solution of potassa in the preparation of the plate was suggested in the early history of the Daguerreotype. It was thought to possess some peculiar property for improving the tone of the impression. It is used for moistening the rotten stone in polishing the plate, and may be prepared by putting about an ounce and a half of alcohol in a close bottle, and add half a stick of caustic potash. This will soon become of a deep red color. For use, fill your small bottle, having a quill in the cork, with alcohol, and add a few drops of the above, or enough to change it to a bright orange or saffron color.

A Substitute for the Hyposulphite Solution.--M. DAGUERRE recommends the use of a solution of salt water for removing the coating off the plate. I found this of some service at one time during my travels. My hyposulphite bottle got broke and its contents lost, so as only to leave enough for preparing gilding. I resorted to the use of salt solution, and found it to answer well. Make a saturated solution of salt in water. First wash the plate with clear water; then immerse it in the saline solution, when it should be agitated, and the coating will soon disappear. Another process with a salt solution of half the strength of the above is very interesting and effectual. The plate having been dipped into cold water, is placed in a solution of common salt, of moderate strength; it lies without being acted upon at all; but if it be now touched on one corner with a piece of zinc, which has been scraped bright, the yellow coat of iodine moves off like a wave and disappears. It is a very pretty process. The zinc and silver forming together a voltaic pair, with the salt water intervening, oxidation of the zinc takes place, and the silver surface commences to evolve hydrogen gas; while this is in a nascent condition it decomposes the film of iodide of silver, giving rise to the production of hydriodic acid, which is very soluble in water, and hence instantly removed.

This process, therefore, differs from that with hyposulphite. The latter acts by dissolving the iodide of silver, the former by decomposing it. It is necessary not to leave the zinc in contact too long, or it deposits stains, and in large plates the contact should be made at the four corners successively, to avoid this accident.

Gilding Solution.--To one pint of pure rain or distilled water add fifteen grains of pure chloride of gold, and to another pint add sixty grains of hyposulphite of soda. When dissolved, pour the gold solution into the hyposulphite by small quantities, shaking well after each addition. The soda solution must not be poured into the gold, as the gold would be immediately decomposed, and the solution turn black, and be unfit for use.

Some operators add muriate of potash and other substances, but these do not possess any advantage except in cases where it is necessary to bleach the solarized portions of the impression, and when such is the case, chloride of sodium (common salt) is probably as effective and is the most convenient. Add about a teaspoonful to two ounces of the gilding.

Solution, for Increasing the Brilliancy of the Daguerreotype.--This solution will have the effect to thoroughly cleanse the surface of the gilded plate and excite a powerful influence on the general character of the impression. To a solution of three ounces of water, in which is dissolved a quarter of an ounce of cyanide of potassium, add one teaspoonful of a solution containing six ounces of water and half an ounce of each pure carbonate of potash, alum, common salt, gallic acid, sulphate of copper, and purified borax. While the plate is wet, pour on a little, and heat it with a powerful blaze. The effect will be quickly produced, in from three to fifteen seconds. Rinse and dry, as in the gilding.

Bleaching Solution.--Make a saturated solution of muriate of ammonia (sal ammoniac) in pure water, and filter through paper. Reduce with an equal quantity of water when used. When the linen or any other portion of the impression is badly solarized, after removing the coating, rinse with water; then pour this upon the surface in the same manner as the gilding solution. If the solarization be very deep, apply the lamp beneath, and warm the plate a trifle. Now pour off, and, without rinsing, apply the gilding. The whole operation must be quickly performed, or the chlorine soon attacks the shades of the picture. When properly done, however, the solarized parts are restored to a clear, transparent white.

Electro, or Cold Gilding.--This process I have adopted, and it produces exceedingly beautiful impressions for the stereoscope, adding a great charm to the pleasing effect of that instrument. It also possesses a pretty and curious effect on views. It is easy of trial, and may be used by dissolving one gramme of chloride of gold in half a litre of ordinary water, and thirty grammes of hyposulphite of soda in another half litre of similar water; then pour the solution of chloride of gold into that of soda, by little and little, agitating it exactly as in M. Fizeau's preparation, of which there is but a variation.

When you wish to use it, pour some into a plate, or any other vessel of the same kind, sufficient to cover the proof; then, after having added to it a drop of ammonia, immerse the plate in it as soon as you take it out of the mercury-box, after having wiped its back and edges, and agitate the mixture quickly from right to left, so as to dissolve rapidly the coating of iodide of silver as usual. As soon as the plate appears white, cease all rapid motion, but continue to give it a slight undulating one; for if it were allowed to remain still for only a few minutes, the proof would be clouded. By little and little, the surface of the plate takes a yellow tint, which darkens more and more, approaching to bistre. You stop therefore, at the color you wish; and when the proof has been washed and dried, in the manner previously explained, it will be found to be fixed, without any stain, with a limpid surface, and an extraordinary warm tone. If you were to augment the proportions of the ammonia or chloride of gold, the operation would progress much quicker, but then the middle of the proof would be always much clearer than towards the border. The mixture may be used several times without being renewed. It does not, however, give such a beautiful color to the impression as when it is newly prepared. By communicating to the vessel containing the solution a continual motion, the impression, when once immersed, will be fixed. During that time, and while attending to anything else, watch its color; and at the end of ten minutes or a quarter of an hour, take it out of the bath and dry it.

Agent for Neutralizing Bromine, Chlorine, and Iodine Vapors.--Aqua ammonia, sprinkled about the chemical or coating room, will soon neutralize all the vapor in the atmosphere of either chlorine, bromine, or iodine. No operator should be without, at least, a six-ounce bottle filled with ammonia. A little of its vapor about the camera-box has a decided and happy effect. Burnt coffee, pulverized, has also the property of destroying the vapors of the above chemicals, as also almost any other agent employed about the Daguerreotype room. Its deodorizing properties are such that if brought in contact with air filled with the odor of decomposing meat, it will instantly destroy all disagreeable smell. It can easily be used in the Daguerreotype room by placing a little of the raw bean, finely pulverized, on an old plate, and roasting it over the spirit-lamp.

Buff Dryer.--There are various methods for keeping buffs dry and free from dust. Some place a sheet of iron against the wall at an angle sufficient to put a lamp between it and the wall, and then let the buff rest against the top of the sheet. By this method the buff is for its full length close to the heated iron, and at the same time exposed to the heated atmosphere and any dust that may be free. I would recommend some arrangement by which the buff would be inclosed. I have found the following to answer the purpose well, which is a box of sheet iron twenty inches long, eight wide and five high, with one end left open and the other closed; the cover is made of the same material, with the edges bent over to go on and off. There are several wires running through the centre of the sides, which it is necessary to cover with cloth or paper to absorb all the moisture that may be made by applying the heat, and the buffs are put in and taken out at the open end. In order that the heat may be as nearly uniform as possible, an iron bar one inch wide, eighteen inches long and one half inch thick, is so bent that the centre is one quarter inch from the bottom of the box, and that at least two inches of each end come in contact with the bottom; this being riveted on the bottom, and a lamp with a small blaze applied to the centre of the bar of iron. This will constitute one of the best and cheapest buff dryers in use. It may be suspended from the wall by placing wires around it, or it may stand upon legs. Perhaps a more convenient plan is to place it under the workbench in a similar position to a drawer. One precaution is necessary: when first heating the dryer, apply but a very gentle heat. This will prevent an accumulation of moisture, which would otherwise pass off in steam, coming in contact with the buff, thus causing a dampness. Another caution: never have the temperature of the air in the heater more than ten degrees above that which surrounds it.

When wheels are used, they should be encased in a sheet iron or wood case. All those made for our market are provided in this respect.

Keeping Buffs in Order.--This is one of the most important objects to arrest the attention of the operator. Every buff is more or less liable to get out of order by dust falling upon or coming in contact with the polishing powder employed in cleaning the plate. The edge of every plate should be thoroughly wiped and freed from any material that may adhere while cleaning. I have adopted the following method, which proves highly successful:

Rub the buff leather, holding the face down, with the sharp edge of a pair of shears or a piece of glass. This brings out any portion of the skin which may have become matted from any moisture, and also takes out any substance imbedded in it, and prevents it from scratching. Then, with a stiff brush, rub the buff well, and it will be found to work well. This same process employ on wheels and hand buffs every morning, or oftener, as occasion requires.

Preparing Buffs.--Two of these are necessary. That part of the stick to be covered should be about eighteen or twenty inches long, and three wide, and made crowning on the face from one end to the other, about one half inch. Before covering, these are to be padded with two or three thicknesses of Canton flannel. The buff should not be too hard, but padded with flannel, so that by drawing it over the plate, it may touch across the surface. The only proper material for buffs is prepared buckskin; and if prepared in a proper manner, this needs nothing but to be tacked upon the stick. There are several varieties of wheels employed; the one most generally adopted is Lewis' patent, which consists of several varieties of wheels. Any operator can make a suitable wheel on the same plan of a turning lathe.

To Clean Buckskins.--When the operator is compelled to purchase an unprepared buckskin, the following is a good process for cleaning it: There is always in the buckskin leather that is purchased, more or less of an oily matter, which is acquired in its preparation, sometimes even amounting, to a third of its weight. The following is the mode of ridding it of this noxious ingredient: Dissolve, in about six or seven quarts of filtered water, about five ounces of potash; when dissolved, wash with the solution an ordinary buckskin; when it has been well stirred in the liquid, the water becomes very soapy, owing to the combination of the potash with the oily matters contained in the skin. Throw away this solution and use some fresh water without potash and rather tepid; change it several times until it remains quite limpid. Then gently stretch the skin to dry in an airy shaded place. When thoroughly dried, rub it well between the hands. It thus becomes very pliant and velvet-like.

Reflectors for Taking Views.--There have been excellent cameras introduced for taking views, but the time of exposure, which is increased in proportion to the focal length, is considered an objection; consequently many adhere to the old plan of using the speculum, or rather, substitute a mirror. I now have one which I have used for several years and find it equal to any article of the kind have ever tried. One is easily made by a tin man, at a trifling expense. Procure a piece of best plate looking-glass, two and a half by five inches for a quarter, or four by eight for a half-sized camera; put a piece of pasteboard of the same size on the back, to protect the silvering, and stick around the edge in the same manner as in putting up a picture. Take a sheet of tin for the large size, or a half sheet for the other; place the glass crosswise in the centre; bend the ends of the tin over the edge of the glass and turn them back so as to form a groove to hold the glass, and still allow it to slide out and in. These ends of the tin must be turned out flaring, that they may not reflect in the glass.

Have a tin band about an inch wide made to fit close on the end of the camera tube; place it on, and taking the tin containing the glass, bring it to an angle of forty-five degrees with the tube, extending nearly the whole length of the glass in front of the lenses; lap the loose ends of the tin on each side of the tin rim, and having your camera turned on the side to throw the view lengthwise, arrange the exact angle by examining the image on the ground-glass. When you have it exactly right, hold it while it is soldered fast to the band. Take out your glass and stain the tin black, to prevent reflection.