The microscope must then be placed in a horizontal position, and the eye-piece removed, the stage having a small clip upon it to keep the prepared plate in position. The negative must then be supported at a distance from the end of the microscope tube from which the eye-piece was withdrawn. This distance will, of course, vary according to the relative sizes of the negative and desired picture. With a one-inch object-glass, which is a very convenient focus, it will have to be changed usually betwixt one and four feet. The negative must be lighted by an argand gas-burner or camphine-lamp, and the rays rendered as parallel as possible by the use of a large lens placed betwixt the light and the negative. It is not easy to arrange the apparatus so as to get the light _uniform_; but a little practice will soon do away with this difficulty. Ordinary ground-glass is too coarsely grained to focus upon, as the magnifying power used to examine the minute reflection must be considerable. One of the slides must therefore be coated with the collodion, submitted to the silver-bath, and after washing with water be allowed to dry. Upon this may be focussed the reflected image, and its minuteness examined with a powerful hand-magnifier, or another microscope placed behind in a horizontal position. When the utmost sharpness of definition is obtained, it is usually required to remove the plate a little distance from the object-glass, as object-glasses for the microscope are slightly “over corrected,” and the chemical rays which accomplish the photography are beyond the visual ones. The exact distance required to give a picture to bear the greatest enlargement cannot be given by rule; but experiments must be made at first, and it will always be the same with the object-glass which we have tested. The plate may now be prepared as in ordinary photography, and placed upon the stage whilst the light is shaded. When all is ready, the shade is removed and the process allowed to go on, usually for thirty or forty seconds; but no certain rule can be given as to the required time, on account of various collodions, lamps, and powers being used. It may be here mentioned, that it is well to contrive some little frame to receive the prepared plate, as the silver bath solution is liable to get upon the microscope stage and so, to say the least, disfigure it. When the exposure has been continued sufficiently long, the picture may be developed by any of the ordinary methods, but some of the best productions have been brought out by the aid of pyrogallic and citric acid solution, with the addition of a little alcohol. The “fixing” may be effected by a strong solution of hypo-sulphite of soda, and the picture must then be very well washed with pure water. When dry, the photograph must be mounted with Canada balsam, in the same manner as any ordinary object; but great heat must not be used, or the picture may be injured.