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  The research archive of Gary W. Ewer regarding the history of the daguerreotype

On this day (September 4) in the year 1891, the following article appeared as the fifth in a series in "The Photographic Times" (New York; pp. 442-3): - - - - - - - - - - - - - - THE RISE AND FALL OF THE DAGUERREOTYPE. AS SEEN BY A COUNTRY "OPERATOR." V. HAVING described the art as it was practiced when I first became acquainted with it, and having strayed somewhat from my story to make some comments upon the durability of its productions as proved by the experience of nearly half a century, it may be interesting to refer back to the opinion formerly held in regard to the permanency of the daguerreotype. It will be seen that a priori reasoning on that question has not been verified by experience. I will quote from a work on chemistry by a professor of this science in the University of Edinburgh: "We are of the opinion that daguerreotype pictures are not durable. We know that they soon fade if not covered with gold, and as this stratum of gold is infinitesimally thin, it will in time oxidize off and leave the picture exposed to the air. It is not to be supposed that so delicate a fabric as one of these pictures should be durable, upon so unstable a foundation as two plates of metal between which, so closely juxtaposed and so antagonistic in their electrical relations there is such great liability to galvanic action." It is curious to read this prediction issued from so high a source and uttered with so much confidence as to have almost the appearance of a scientific deduction. Still more curious are the reasons given for this oracular utterance: First, the "so delicate a fabric," and second, the "so unstable a foundation." The fabric was silver, mercury, and gold, made to unite by heat, and it is doubtful that any other picture produced by photography has contained as much substance in its structure as the daguerreotype. The toning bath for example contained fifteen grains of the chloride in a quart of water, and the gold was precipitated upon the picture by heat in much greater quantity than any silver print could be made to take. I have referred to boiling these pictures in cyanide of potassium. They may also be boiled in sulphuric acid without injury--an experiment which I have often made to rid them of some scum which the cyanide would not remove. In short, the time when the gold will be oxidized off and the picture left exposed to the air seems to be yet somewhat remote. It is also interesting to note the objection raised by this renowned scientist to the unstable character of the foundation upon which the poor "daguerreotype picture" must needs rest during the brief period which would elapse before it would be deprived of its infinitesimal protection of gold by the relentless tooth of the fell destroyer, oxygen. This "unstable foundation" was no less than two plates--one of copper and one of silver, "so closely juxtaposed" as to form one plate. Strange to say, it has failed to maintain its early and perhaps premature reputation for instability. To return to my story: While learning the first lessons in the practical knowledge of the art I was also getting together the requisite appliances for putting this acquisition into practice. What I could not obtain on credit I bought with borrowed money or manufactured. For a Daniels battery I procured a copper cup of suitable size and shape at a tinsmith's; constructed a mould of wood and paper, and cast a porous cup of plaster of Paris which proved to answer the purpose well; cast a cylinder of zinc in a sheet iron matrix, and by attaching copper wires to the cup and cylinder in the simplest manner possible it wanted only the necessary solutions to put it in complete working order. Then dissolving a sufficient quantity of silver coin in nitric acid I precipitated the chloride with common salt, which left the nitrate of copper (the alloy of the coin) in the solution. After washing the chloride with several changes of water until no blue color was visible nor became visible on adding a drop of ammonia to the water, the chloride was mixed with an excess of carbonate of sodium in a crucible, and on heating it sufficiently a button of pure silver was obtained, which being hammered out into a plate on a clean anvil it was attached to the positive pole of the battery. A supply of hydrofluoric acid was also required. This was produced as follows : A quantity of pulverized fluor spar (fluoride of calcium) was placed in a leaden retort; to this was added about three parts common sulphuric acid. The retort was made in two parts, the upper part fitting over the lower, and after being charged, the joint was luted with clay. The neck of the retort was fitted to that of the receiver by a ground joint and the receiver was surrounded with ice and salt or ice-cold water. Then on applying a gentle heat to the retort, which was placed in a sand bath under a flue, the acid was generated and passed over into the receiver. The acid was, of course, kept in a bottle of lead. I also made up a small stock of chloride of gold. A piece of gold coin was dissolved in three parts of hydrochloric acid to one part of nitric acid (each of these parts being equal in weight to the gold). The solution was then decanted from the flask, leaving the precipitated chloride of silver (from the alloy) which was washed with several changes of water and this water added to the other solution. The copper of the alloy being in solution with the gold was separated from it by adding an excess of a saturated solution of copperas filtered and made clear by a few drops of sulphuric acid. This precipitates the gold in the form of a dark brown powder, which being also washed to free it from the copper and iron, is redissolved in the nitrohydrochloric acid as before. As the American gold coin is one-tenth alloy it is easy to determine the amount of pure gold and of pure terchloride that should be obtained from it. For example a five dollar piece weighs 129 grains. Deducting one-tenth we have 116 grains of pure gold, and this should give 178 grains of pure chloride. If now after the gold is redissolved a quantity of dried table salt equal in weight to that of the pure chloride due from the gold be dissolved and added to it the mixture will be a solution of chloride of gold and sodium, and when evaporated nearly to dryness the double salt will be in a convenient form for handling and use, and in all respects equal for use to the pure and much more deliquescent single chloride. At the present day, if wanted for toning photographs, it is better to leave the copper and not separate it from the gold. Find how much pure chloride of gold is due from the coin; and add the salt to the first solution described above as when freed from the chloride of silver, making no account of the copper; then evaporate down as before directed. The rule for finding the chloride, the weight of pure gold being given, is as follows: As 200, the combining weight of gold, is to 306.5, the combining weight of the terchloride, so is the weight of the gold given to that of its chloride. As in the above, 200: 306.5:: 116: 177.77. In reality the quantity of chloride obtained is much greater. The formula gives only the weight of the anhydrous salt, and the difference between this and that obtained by the process described affords a handsome profit. I have found that 30 grains of the double salt are fully equivalent in toning power to 15 grains of the pure chloride from the most reliable houses. W. H Sherman. (To be continued.) (Previous installments appeared on Jan 20, March 13, April 17, and May 15 and were posted to DagNews in 1997 on the date of their original publication. The sixth installment will appear on September 18.) -------------------------------------------------------------- 09-04-97

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