78

DAGUERROTYPE.

provements for which he obtained a patent in June, 1840. The first of ^ gcur a.the substitution of a concave reflecting mirror for the lens in the camera o g jteFig. 36 represents in section a slight wooden box, a a, open at the front, 0 J^- rr or,to the person sitting for the portrait. In the back part of the box a concave ^ eb, is placed, to reflect the rays coming from the person. A small frame, e, 1 ^jieto an adjustable pedestal, d , which slides in grooves in the bottom of the Gox, .j s jiedpurpose of being set at the focal point of the mirror. In this frame, e, a P ^surface is first to be placed for trial, to receive the image correctly, as observe * ie ioperator, by looking through the opening, e, in the top of the box. The V - n0 ussilvered plate is now substituted in the exact place for the trial one. The 1 f u ]lyimpression being made, the slide, d, is withdrawn, and the plate removed; cshut up in a box from the light. -form, W

The second object of this patent is making the prepared surface more uni ar den e ^passing two plates, with their silvered faces in contact, several times between nrollers, annealing them at a low red heat after each passage. . j a tter

His third object is to use a compound of bromine and iodine, instead ot t . eB \ogalone, for coating the silver; which increases its sensibility to light, thereby sil ^ c0I n-and improving the operation of taking likenesses. He also recommends to us gere enbination of iodine with nitric acid. Finally, Mr. Beard finds that by placing a ;t isof any desired color behind the sitter, the appearance of his Daguerrotype Pimproved. ( Newton’s Journal, xxiii. 112.) 0 btai ne . d

M. A. J. F. Claudet, who had also purchased a license from M. Daguerre, jjisa patent in December, 1841, for certain improvements upon the original P roce w ’ a dBi> tfirst object is to give the front of the camera obscura such an aperture as ^the largest object-glass intended to be used; and of such he provides a series ^ r(J[) tferent dimensions, each attached to its board, that may be fitted by a slide to

of the camera.

One of the greatest difficulties in the Daguerrotype process was the * B1 P? SS1 t)r epa re ^ascertaining the precise moment at which the light had produced, on the 1 a ppW'plate, the effect requisite for the vapor of mercury to bring out the image- ^ jjgbbing that vapor to the plate while the silver surface is being acted upon by j a gethe operator is enabled to see when his picture is complete. Another ad ■ platethis joint operation is, that the effect of the mercury upon those parts o* ^ p)ac ewhich have been acted upon by the light, are more perfect when caused t0 ,- t j n cl bo*immediately under the luminous influence. Hence, instead of using th e a _, rEl ob'with the cup of quicksilver, he places a cup containing that metal in the ca ^„ r jgenscura, with its spirit-lamp, and exhales the vapors there. When the mercury ^ theto the proper temperature, the aperture of the object-glass is thrown open,light, reflected from the object to be delineated, is allowed to operate. vie^ s

He watches the effect through an opening in the side of the camera, W-n er ^. ora n? e "the prepared plate by the light of a lantern passing through a piece of /Id mercdfjcolored glass in the (other) side of the camera. Whenever the light a coV eI e ^’by their simultaneous action, have produced a good image, the object-gloss ^ n jslt e “*and the silver plate, with its picture, removed, in order to be washed an ^ sC rc en jjM. Claudet embellishes his Daguerrotype portraits by placing behind theof painted scenery, which furnish pleasing back grounds. He specifies akinds of artificial illumination, to be used in the absence of solar light -Journal, C. S. xx. 430.) ^ f or hah. _

According to M. Barnard, Daguerre’s iodized plate should be ex P? s aon) nion aIt Jminute to the action of chlorine, mixed with a large proportion ot t he sb®whereby it becomes so sensitive, that the pictorial impression is producespace of time necessary for removing and replacing the screen of the 0 type 1".mercury is afterward employed; as also the hyposulphite wash. • bore imw ed ! a a b-tures are colored by dusting over them powders of proper hues, which a eJ . t in9 awashed by passing the plate through water. What remains of the c0 formlution does not seem in the least to injure the appearance or alter tn ’

image. It would seem that those parts of the picture which were at par* 8 '

after being washed, a larger proportion of the coloring matter than the on the ”Several valuable improvements seem to have been made in Vienna guerrotype process; and among others, the mode of using chloriodine. itsbotto® fThe best form of box for applying the chlonodic vapor is square, w ^ e ; n g ° n ?i 0 oplate glass, supported a little above the table by feet, a thumb-screw (he cbithem, in order to.give a certain inclination to the glass plate for s P^ e ^ ^ox, ena ; 3 »iodine over it uniformly. A sheet of white paper being laid beneath Th ere 0 m-

the operator to see whether the liquid chloriodine is properly distribute ■ A ther jn w

of

groove round the top of the box, into which the ledge of the lid fits tight,eter is placed in the box.

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