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nearer the lens than the luminous focus. in the art of Daguerreotyping bas enabled This unlooked-for result he ascertained to him to produce portraits of great beauty be owing to an overcorrection of the cliro- and force. The portraits taken by Mr. matic aberration of the less refrangible Kilburn, and colored by a chlebrated Parays, and he found this “to be generally risian artist, M. Mansion, are exceedingly the case with object-glasses in which, by attractive, while those of Professor Highthe excess of the dispersive power of the school, from America, executed by new proconcave glass, or the irrationality of that cesses, and some of them tinted by peculiar dispersion, the extreme rays of the most methods, exhibit great chemical knowledge, refrangible part of the spectrum are, during and evince much experience in the practice the second refraction, diverged in a greater of his art. He has employed with much proportion than they have been converged success the vapors of cadmium, antimony, by the refraction of the convex lens; and arsenic, and also of several metallic alloys, these rays being nearly invisible, do not and from his devotion to the subject we affect the achromatism of the luminous have no doubt that he will make still rays.”. M. Claudet, therefore, recommends greater additions to the resources of photothat the rays of the photogenic spectrum graphy. His very interesting series of pashould be united in one focus, even at the noramic views of the Falls of Niagara, were, sacrifice of the achromatism of the more re- we believe, the first ever taken by the Dafrangible rays. As the photogenic focus, guerreotype. however, will change its place with the co- The Daguerreotype pictures produced by lor and intensity of the light, and with the the methods which we have now described, distance of the object, the photographer being caused by a slight deposit of mershould determine experimentally its posi- cury, resembling the bloom upon a plum, tion in relation to these varying influen- which is effaced by the slightest touch, ces.
could scarcely be regarded as durable or In many of the early Daguerreotypes the permanent works. In order to remedy this pictures were reversed—that is, the right evil, M. Dumas proposed to protect them side of the picture was the left side of the with some transparent vegetable varnish; landscape ; but this intolerable evil, which but as this coating was not proof against does not take place in the Talbotype, was damp and atmospheric influences, it has soon corrected-in some cases by reflexion never been satisfactorily applied. The from a glass or metallic mirror, and in oth- object, however, which Dumas contemplaters by a prism, which is decidedly the best. ed has been effected by M. Fizeau, by a As much light, however, is lost by these very beautiful and simple process. Having reflexions, and the time of sitting prolong-covered the silver plate containing the piced, artists have scrupled to correct the re- ture with a solution of chloride of gold, version of the picture. M. Claudet, indeed, mixed with a solution of hyposulphite of is, so far as we know, the only person who soda, in certain proportions, and then exmakes a point of correcting the reversion of posing the plate to the gentle heat of a the picture ; and he has placed it beyond a spirit-lamp, the metallie gold is precipitatdoubt that a picture not reverted, is a more ed upon the plate, and forms a thin transartistic and truthful representation of the parent coating, which gives a rich tone to individual than a reverted one. We have the picture. The gold precipitated on the long been convinced of this truth; and if plate forms an amalgam with the molecules any person doubts it let him look at the or crystals of mercury, and by adding to two sides of a Calotype made transparent their size increases the brilliancy and force by the process which we have already de- of the picture. Other metals have been scribed, and though the two portraits are precipitated by the electrotype process, but mathematically the same, he will see that the precipitates are less transparent and in the air and even in the likeness, they adhesive. The process of M. Fizeau, beare essentially different.
sides fixing the picture, enables the artist By means of these processes, portraits of to color his portraits—a most desirable rea very superior character are now taken sult, which could not have been otherwise professionally by several distinguished ar-effected. tists in the metropolis, by M. Claudet, Mr. To the same ingenious author, M. FiKilburn and Professor Highschool, each of zeau, we owe the beautiful art of reproducwhom have distinguished excellences of ing the Daguerreotype pictures by the their own. M. Claudet's long experience / electrotypo process, which was discovered VOL. XII. No. II.
in the same year with the Daguerreotype.* the battery when put in action. This elegant In this new process metals are precipitated process, however, owing to the breaking of from their solution by the action of electri- the delicate coating which protects the silver, city, the precipitate being deposited on is still susceptible of further improvement. every part of the picture, so that when the M. Fizeau, to whom the photographic metallic film, or plate thus formed, is re- art is so much indebted, has given us anmoved from the surface of the Daguerreo- other method of etching the plate. He emtype, it resembles it so exactly that it ploys a mixture of nitric acid, nitrous acid, would be impossible to decide which was and chlorohydrid acid, which attacks the the original and which the copy, did we not silver and not the mercury. The chloride know previously of what metals they were of silver is formed by the action of the acid respectively composed. This perfect re- upon the silver, and stops its action, but semblance between the original and its im- the coating of chloride is removed by a sopression shows that the Daguerreotype lution of ammonia, and the biting continuimage consists of minute crystals, produced ed by fresh acid. This operation is repeaton the surface of the plate by the combined ed till the plate is etched. In order to inaction of the mercury and the iodide of crease the depth of the etching, M. Fizeau silver, that the lights arise from these re- gilds the white parts, which he does by fillflexions, and that similar reflecting faces ing the bitten parts of the silver with a are produced on the electrotyped plate. siccative ink. By wiping the surface
As the Daguerreotype pictures cannot be slightly, the ink fills up only the hollow multiplied like the Talbotype ones, it be- parts, and the mercury remains perfectly came desirable to discover some method of unprotected. He then immerses the plate fixing them on the plate by a more perma- in an electrotype battery, charged with a nent tracing than mercurial lines, and to solution of gold, and as soon as the contact make this plate the means of their repro- is established, the gold is precipitated on duction. The first person who partially the white parts only, the greasy ink presucceeded in this attempt was M. Donné, venting the precipitation upon the silver. who, after covering the edges of the plate When the gilding is completed, the ink is with a protecting varnish, poured upon its removed by caustic potash, and the plate surface a weak solution of nitric acid. again submitted to the action of nitric While the pure silver was bitten in by the acid. The etching commenced by the first
. action of the acid, the other parts, protect-operation is now continued, the part which ed by the mercury, remained untouched, is to remain in relief being protected by provided the action was not long continued. the gilding. A plate thus etched, will give As the impressions given by these etchings a great number of very good impressions ; were very faint, Dr. Berres of Vienna used | but as it would soon be worn by the printthe vapor of dilute nitric acid, and applied ing, M. Fizeau recommends, in order to a varnish to the parts of the plate which protect the original, and insure a great required to be protected; but this method, number of copies, that it should be electrorequiring the skill of an artist in laying on typed, so that from one matrix any number the varnish, has been as unsuccessful as of copper-plates may be produced, and that of M. Denné.
from them any number of copies printed for The process of etching Daguerreotypes, publication. though considered, after these failures, as We have already seen that the sun carbeyond the reach of art, has been greatly ries upon his palette only one color. He improved by the agency of electricity paints but with china ink' or bistre. From Professor Grove, availing himself of the the pure white of his virgin beam, he reproperty of the Voltaic battery to precipi- fuses to disenchain the mystic hues which it tate at the positive pole metals placed at embosoms and combines. The gay colors the negative pole, places the Daguerreotype of the natural world, whether they sparkle plate at the negative pole, and by the use of in leaf or in flower, on the insect wing or on solutions which attack the pure silver surface the virgin cheek, appeal to him in vain. in preference to the amalgamated metal, Even his own setting glories he refuses to the biting of the silver is effected after it fix. He lights up indeed with new brighthas been immersed only a few seconds in ness the azure vault, as if to entice to the
• The process of M. Fizeau was communicated upward but difficult ascent. But the gold of to the Academy of Sciences on the 15th and 25th Cræsus shines dim on his canvas, and he May, 1841,
refuses to give expression to the scarlet
vestments of power, and the red banners of will appear to be all but impossible, when
*to believe it so.
while Mr. E. Becquerel maintains, as we rays, and another analogous to the effect of have seen, that they have the property of these rays. continuing the action of the ordinary pho- The photogenic action of the red ray is, togenic rays, when once commenced. In according to M. Claudet, 5000 times this state of the subject M. Claudet began slower or weaker than that of white light; a series of experiments which led to valu- that of the orange rays 500 times; and that able results, and of which he has enabled of the yellow 100' times. us to give the following abstract.
The destructive action of the red rays is Having directed a camera, with an 100 times slower or weaker than that of iodized plate, to the sun when his disc was white light, the orange 50 times, and the quite red, he left it there for twenty yellow only 10 times. minutes. The sun had passed over a great When a plate has been exposed to the space on the plate, which was marked with destructive action of any particular ray, it a long and perfectly defined image of his cannot be affected photogenically by the disc, so that not only had the red sun pro- same ray which acted destructively, and it duced no photogenic action, but the red is sensitive only to the other rays; and the rays had destroyed the effect produced by photogenic or destructive action of any ray the previous action of the sky. By moving cannot be continued by another. Hence the camera from right to left and from left M. Claudet draws the important conclusion, to right, and lowering it each time by that the solar spectrum is endowed with THREE means of a screw, he made the sun pass different photogenic actions, and three differrapidly over five or six zones of the iodized ent destroying actions, corresponding to the plate. The lines of his passage were mark- red, yellow, and blue rays. The rays of ed with long black bands, while the inter- each of these colors is endowed with a phovals between them were white, proving togenic power peculiar to itself, which again that the red rays had destroyed the causes the mercurial vapor to adhere to the previous photogenic action. M. Claudet iodized plate, and yet these three actions obtained the very same result with red, are so different that we cannot by combinorange, and yellow glasses. The impres- ing them artificially make the one assist the sion of black lace taken by white light was other, on account of their antagonistic chadestroyed by the rays passing through a racter. The effect of the blue rays is dered glass, and the same effect was produced stroyed by the red and yellow, each of in different periods of time by orange and which is in its turn destroyed by the blue, yellow glasses. But what was very re- while the yellow and red mutually destroy markable, M. Claudet discovered that after each other. Hence it would
that the photogenic effect was destroyed, the the iodide of potash remains always the plute was restored to its former sensitiveness same under these different influences, and to white light, nay, we may expose the plate that there is no separation or disengageto these two actions alternately, for any ment of its constituent elements. number of times, and yet it will be sensi- Several curious phenomena connected tive to the vapor of mercury, if its last ex- with photography have been recently obposure has been to white light, and will be served and studied by different philosodeprived of that sensitiveness if its ex- phers. It had been long ago noticed, that posure has been to the destroying action of if we write upon a piece of glass with a the red, orange, or yellow rays. Hence M. pencil of soapstone, the words, though perClaudet arrives at the important practical fectly invisible, may be read by simply result, that the Daguerreotype plates may breathing upon the glass, and the experibe iodized in open daylight, and that in ment will succeed even if the surface is order to restore their sensitiveness, which rubbed with chamois leather after the that light has destroyed, we have only to words are written. Dr. Draper has often place them for a few minutes under a red noticed that if a coin or a wafer is laid glass, before we place them in the camera. upon a piece of cool glass, or metal, and M. Claudet has shown that the discovery the surface be breathed upon once, and if, by Dr. Draper, of a photogenic action in as soon as the moisture has disappeared, the red half of the spectrum, is true also the surface is again breathed on, a spectral for the rays which pass through red, orange, image of the coin or wafer will be seen, the and yellow glasses, thus proving that these vapor being deposited in a different manrays have two contrary actions, one de- ner upon the part protected by the coin or tructive of the effects of the photogenic wafer. The impression thus communicated
to the surface, under certain conditions, | images may be formed upon the traces of remains there for a long time. “During words by gaseous bodies--the letters being the cold weather,” says Dr. Draper,“ last written as it were in bubbles of gas. Hence, winter (1840-1841) I, produced such an as he shows, we have the cause of the efferimage on the mirror of my heliostate: It vescence produced by the immersion of a could be revived by breathing on the metal piece of bread in champagne. This curimany weeks afterwards, nor did it finally ous subject has been recently studied by disappear until the end of several months., M. Ludwig Moser of Berlin, who has arrived Dr. Draper has also shown that a series of at several very important conclusions, which spectra may co-exist on a phosphorescent our limits prevent us from giving, othersurface (sulphuret of lime), and after re- wise than in the following abbreviated maining latent for a length of time, will form :come forth in their
order on raising If the surface of a solid body has been the temperature of the surface. Place a touched in any particular part by anokey, for example, on a phosphorescent sur-ther body, it acquires the property of face, and make that surface glow by a gal- precipitating on the touched part all vapors vanic discharge between charcoal points for which adhere to it, or which combine two or three minutes-the image of the key chemically with it, differently from what it will of course be seen after removing it. If does on the untouched part. the surface, kept in the dark for a day or This result was obtained with all bodies two, be now inspected, no image will be such as glass, metals, resins, wood, pastevisible, but when laid upon a piece of warm board, &c., and in order to produce the iron a spectral image of the key will be
be effect absolute contact was not necessary ; seen. Take a similar plate similarly im- a shilling held above mercury and then pressed by a key, but whose image has not breathed upon gave the image of the shilbeen involved, and having set before the ling, as when it was laid upon a plate of surface another object, such as a metallic glass and subsequently breathed upon. ring, discharge at a short distance a Leyden Mercurial vapor, and that of iodine, acted jar. The phosphorus will shine all over | exactly like the vapor of water.
Hence the except on the portion shaded by the ring. phenomenon of the Daguerreotype was proThis image of the ring soon disappears to- 'duced without the intervention of light, for tally; but if the plate is set upon a piece the experiments were equally successful by of warm iron it will speedily begin to glow, night as by day, and consequently " conthe image of the ring will be first reproduced, tact is capable of imitating the action of and as it fades away the spectral form of the light.” key will gradually unfold itself, and then After showing, by experiment, that “the vanish.
violet rays continue the action commenced Invisible traces of written words have by contact,” he examines the action of light been rendered visible in several curious upon plates of silver, copper, and glass. phenomena of crystallization. Dr. Draper “A clean and highly polished plate of observed, that if we draw a line on the silver, having a pattern cut out of paper interior of a glass-receiver containing cam- suspended over it, without touching it, was phor, and if we expose the receiver to the exposed to the sun for some hours. After sun after it is exhausted of its air, the line being cooled, it was held over mercury described will be stellated with crystals of heated to about 60° of Reaumur, when a camphor. If we make a solution of a few clear image of the pattern was produced by grains of sulphate of magnesia, and three of the mercurial vapor.” From these, and carbonate of ammonia, in an ounce and a other experiments, Moser concludes, " that half of water-or, what Dr. Waller prefers, light acts on all bodies; and that its influof ten grains of phosphate of soda instead ence may be tested by all vapors that adof the sulphate of magnesia—and spread- here to the surface or act chemically upon ing this solution upon a plate of glass (or it ;” and that “the same modification is upon quartz or agate), write with a pen prodused upon plates when vapors are conupon the glass, the words will become visible densed, as when light acts upon them." (by the deposition of crystals,) both on the M. Moser has endeavored to explain these, glass and on the surface of the fluid! Dr. and various other phenomena, on the hypoWaller, to whose interesting paper we refer thesis that every body is self-luminous, our readers-(Phil. Mag., Feb., 1846, vol. and emits invisiblo rays of light," and that xxviii., p. 94)—has shown that similar when two bodies are sufficiently approxi