3144. To Develop a Negative

3144.     To Develop a Negative. This is done by removing the plate from the holder, and, holding the plate in a horizontal position, flowing it with the developing solution. (See No. 3151 (Developing Solution).) If properly timed or exposed, the image begins to appear. When the details of the drapery, if a portrait, appear and the solution seems to have lost its power, the plate is thoroughly washed under a stream of clean water. If the image is sufficiently strong and vigorous, it is " cleared" by placing the plate in the fixing bath, and that portion of the film not acted upon by the light is dissolved away, leaving the image upon the glass. After a thorough washing in water, the plate is put in a rack to dry, after which it is slightly warmed and varnished.

3145. To Varnish, a Negative

3145.    To Varnish, a Negative. The varnish (see No. 3153 (Negative Varnish)) is flowed on and off' precisely as with the collodion. (See No. 3143 (To Make a Photographic Negative).) It should be again slightly warmed to prevent the varnish from chilling or blooming. When dry, which will be in 5 to 10 minutes, the negative is ready for use as described in Nos. 3135, etc., using the negative instead of the leaf. Should the image have evidence of full exposure by the existence of all the proper detail, and yet want vigor or intensity, this may be imparted, before varnishing, by re-development.

3146. To Re-develop a Negative

3146.     To Re-develop a Negative. This is done by pouring upon the plate about 1 ounce of the pyrogallic acid solution to which has been added 5 or 6 drops of the silver solution designated for that purpose. (See No. 3152 (Re-developing Solution).)

3147. Glass for Photography

3147.    Glass for Photography. For portraiture and ordinary landscape photography, the best qualities of picture or window glass will suffice. There is an article sold by dealers in photographic materials, known as photographic or negative glass, which is selected for the purpose and cut into the regular sizes used in the art, viz., stereoscopic, "quarter" size, "half" size, "four-four" etc., the latter being 61/2 X 81/2 inches and the other sizes fractional parts, as their names suggest. For microscopic and scientific experiments, plate glass would be preferable. A quality known as " three quarter white " plate, and only of the thickness of ordinary single thick window glass, has all the requisites for exact photography. When it is proposed to print photographs upon glass, for magic lanterns or transparencies, plate glass is absolutely essential.

3148. To Prepare Glass for Photography

3148.    To Prepare Glass for Photography. All new glass should be placed for a few minutes in a strong solution of commercial nitric acid (say 1 ounce nitric acid to 3 ounces water), and then thoroughly washed in clean water. While wet, pour upon the glass a solution consisting of white of egg, 1 ounce; water, 20 ounces; drain off into a separate bottle, or clean, filter, and set up in a rack to dry. The albumen and water solution, before using, should bo very thoroughly beaten together. After the froth has subsided, filter the solution through a clean sponge, two or three thicknesses of linen, or, still better, filtering paper. The solution above named will coat more plates than an amateur would be likely to use. Use fresh eggs and a newly made solution whenever coating plates. The plates so prepared will keep indefinitely.