"This poor widow hath cast in more than they all."
Widowed of the world, that once did me betroth.
Unto the treasury of God brought I,
In after days,
A heart and mind—my all—two mites in worth,
And cast them in. What wealth, if they should buy
Such priceless praise!
MISCELLANY.
A most Important Discovery in Photography.—That photographic productions cannot be relied upon as permanent appears a fact only too well established. The public have been convinced of it by seeing folios of choice productions and scores of treasured portraits pass gradually into "the sere and yellow leaf" of their age, and finally disappear. A few years, more or less, generally works the change. Photographers, too, have lost all faith in the absolute permanence of their productions, and have long been looking for this desirable quality in some ideal process for which their experimentalists were industriously striving and working, and for which they were most anxiously looking, rather than to any modification of the old silver process, which they have now wrought up to such a pitch of perfection. This fading has been pretty clearly shown to be, at least mainly, due to the action of the hyposulphites. The print lasts a longer or shorter time in proportion to the degrees in which the fixing agent—hyposulphite of soda—has been removed from the paper; but the slightest trace of it will assuredly bring about the destruction of the photograph. The only chance of absolute permanence appears to be in its complete elimination, although even then there are other elements of evil which may be suspiciously regarded. We have hitherto relied for this purpose upon the mechanical action of water, and some able men have run counter to the general experience by affirming that absolute permanence could be obtained by proper and sufficient washing. Mr. Carey Lea, for instance, asserted, about a year since, that he had tested properly-washed prints with a very delicate and certain test for the hyposulphites without discovering their trace, and in prints which he considered had been properly washed. This test was that of placing a few drops of an alcoholic solution of iodine in several ounces of water, and applying the same with a camel's-hair brush to photographs on starch-sized paper. The presence of the starch, if freed from the hyposulphite by sufficient washing, was indicated by a violet or purple stain where the solution was applied; but in prints not thus washed the presence of hyposulphite was indicated by the absence of such stain, which could be at once removed from the well-washed print by plunging it into a solution of hyposulphite. On the other and, Mr. Dawson, of King's College, in a recent number of The British Journal of Photography denies the power of more washing to give permanence, "unless the prints have been soaked for some time in hot water so as to remove all the size—even then, supposing the paper non-albumenized, the elimination of the whole of the hyposulphite is problematical." He adds—"Some photographers, we are aware, do treat their prints with a final wash in hot water; but this, of course, although unquestionably conducive to the permanence of the proof, does not remove the whole of the size in which the hyposulphite is locked up; and if it did, the paper would be as little cohesive as blotting-paper, and prints would lose much in vigor and brilliancy. In the case of prints on albumen, or albumenized paper, hot water, we may reasonably suppose, has no more powerful effect in removing hyposulphite from albumen than cold water, if, indeed it has so much; and it can only be by acting on the texture of the paper itself, and removing the size therefrom, that it can exercise a beneficial influence at all." To demonstrate the truthfulness of his ideas on this subject, some prints which had been washed in cold running water, and with the utmost care and attention, for over twenty hours—and the final drippings from which, when subjected to the tincture of iodine test, displayed no trace of the hyposulphite—were experimented with, and still gave up to boiling water, in which they were steeped, at least one-fortieth part of a grain of the destructive element to the half sheet of paper, clearly showing that the cold water had not really removed it all, although it had eliminated all that it could reach or had influence over. Now whether Mr. Dawson and his supporters or Mr. Lea and his supporters be right, [{425}] whether photographs fade so universally because they are rarely or never sufficiently washed after the process of fixing, or because it is impossible to remove all trace of the hyposulphites from the paper by washing, it is certain that they do fade, and few dispute the final cause of such a fading. Therefore, a discovery which destroys these mischievous agents altogether cannot but be regarded as most important, and such a discovery is our pleasing duty to announce as having been recently published by Dr. Angus Smith, F.R.S., in the pages of The British Journal of Photography, from which we quote: "Considering that the cause of the destruction of photographs, apparently by the action of time only, was in reality caused by the amount of hyposulphite remaining in the paper, D. Reissig, of Darmstadt, contrived a mode of washing it out by centrifugal force. For indicating the presence of sulphur assets, he used a small galvanic arrangement with one cell, and decomposing the acid, had the sulphur thrown on a piece of polished silver, which became readily blackened in the solution. Dr. Theodore Reissig, my assistant, examined several faded photographs for me by his brother's method, which, however, appeared unnecessarily delicate, as it was found the amount of sulphur was very large, and roughly, we thought, in proportion to the amount of decay. I did not determine how much was hyposulphite and how much sulphate. As I had been interesting myself in bringing into use some of the remarkable properties of peroxide of hydrogen in oxidizing metals and organic bodies in fluids, it seemed to me that we might readily use it for oxidizing the hyposulphites. I am supposing that the sulphate alone will not be injurious." Dr. Smith then shows how this powerful, oxidizing agent may be used to convert the mischievous hyposulphites into the innocuous sulphate, and Mr. Dawson, in the same number of the journal, gives the following experimental illustration: "Dissolve in a wineglass any quantity of sulphate of soda, and add to the solution a few drops of tincture of iodine. The solution will remain permanently discolored, showing that sulphate of soda does not dissolve iodine. In another wine-glass, half filled with plain water, drop sufficient tincture of iodine to strike a permanent dark sherry color throughout the liquid; then add, drop by drop, a weak solution of hyposulphite of soda till the color is discharged, taking care to add as little excess of hyposulphite as possible. So far this experiment shows that iodine is soluble in hyposulphite of soda. Now, fill up the glass with an aqueous solution of peroxide of hydrogen, and observe the effects. After a few minutes the iodine is no longer held in solution, and the liquid will resume the dark sherry color it had before adding the hyposulphite of soda." Every chemist will readily explain this. To apply this new chemical agent to this new use, take the print, after fixing and washing, and soak it for a short time in a solution of the peroxide of hydrogen of the strength of say one ounce of a ten-volume solution in forty ounces of water.—Popular Science Review.
ORIGINAL.
NEW PUBLICATIONS
PASTORAL LETTER OF THE SECOND PLENARY COUNCIL OF BALTIMORE. The Archbishops and Bishops of the United States, in Plenary Council Assembled, to the Clergy and Laity of their charge. Baltimore: John Murphy & Co. 8vo pamphlet. For sale by L. Kehoe, New York.