The History and Practice of the Art of Photography [19]
III. MERCURY BATH.--Fig. 13 gives a front view of the mercury bath now in general use in this country for mercurializing and bringing out the picture. It is quite an improvement on those first used. To make it more portable it is in three pieces, a b and c; having a groove e on one side to receive the thermometre tube and scale by which the proper degree of heating the mercury is ascertained. Into the top are nicely fitted two or three iron frames, with shoulders, for the plate to rest in, suitable for the different sizes of plates. The bath is heated by means of a spirit lamp placed under it. From two to four ounces of highly purified mercury are put into the bath at a time.
IV. PLATE BLOCKS AND VICES.--There are several kinds of this article in use; I shall describe the two best only.
Fig. 10 gives an idea of the improvement on the English hand block. The top a is perfectly flat [hipho_10.gif] and smooth--a little smaller than the plate, so as to permit the latter to project a very little all around--having at opposite angles c c two clasps, one fixed the other moveable, but capable of being fastened by the thumb screw d, so as to secure the plate tightly upon the block. This block turns upon a swivle, b, which is attached to the table by the screw c, This block is only used for holding the plate while undergoing the first operation in cleaning. [hipho_11.gif]
Fig. 11, shows the form of Lewis' newly patented plate vice, which for durability, simplicity and utility is preferable to all others. It consists of a simple platform and arm of cast iron, the former, a, having a groove, d, in the centre for fixing the different sizes of plate beds, e--and the latter supporting the leaves, e f. On this vice which is secured to a table, or bench, the plate receives its finishing polish with rouge, or prepared lampblack. Mr. Lewis gives the following directions for its use. "As the cam wears tighten it with the adjusting screw (g) so as to allow the lever (f) to fall back into a horizontal position; the plate being in its place at the time. Oil the wearing parts occasionally."
Some Daguerreotypists, however, use a foot lathe with buff wheels of various forms; but this vice is sufficient for all ordinary purposes.
V. COATING BOXES.--The usual form for iodine and [hipho_12.gif] [hipho_13.gif] bromine boxes is see, at figs. 14 and 15. They are far superior to those in use with the English operators. Each consists of a wooden box (a,) having firmly embeded within it a stout glass jar (c), the edges of which are ground. Over this is placed the sliding cover b, double the length of the box, one half occupied by a piece of ground glass (e), tightly pressed upon the glass pot by a spring (i) beneath the cross bar g, and fits the pot so accurately that it effectually prevents the escape of the vapor of the iodine, bromine or other accelerating liquid contained therein. The other half of the lid is cut through, shoulders being left at the four angles for the different sizes of frames, designed to recieve the plate while undergoing the coating process. When the plate is put into the frame, the cover b is shoved under the second lid h and when coated to the proper degree, it resumes its former position and the plate is placed in the holder of the camera box. To test the tightness of the box, light a piece of paper, put it into the pot and cover it with the sliding lid. The burning paper expels the air from the pot, and if it be perfectly tight you may raise the whole box by the lid.
VI. GLASS FUNNELS.--Are a necessary article to the Daguerreotypist, for filtering water, solutions, &c. [hipho_14.gif]
VII. GILDING STAND.--For nervous persons the gilding stand is a useful article. It is adjusted to a perfect level by thumb screws placed in its base.
VIII. SPIRIT LAMPS.--The most useful and economical of those made are the Britania, as they are less liable to break; and the tube for the wick being fastened to the body by a screw renders it less liable to get out of order or explode. Glass is the cheapest, and