By Charles A. Stinson, Supt, Gatchel & Manning, Illustrators and Engravers, Philadelphia, Pa.

960. The "wet plate process" is the method used by the photo-engraver in making the negatives for half-tone and line engravings. It is not only the first part of the process, but is also one of its most important stages, and requires considerable judgment and skill to produce the "proper kind" of a negative.

961. While there are several different formulae in use, it is only necessary for the student to acquire the knowledge of one of each of the different stages (the ones given in this article are amongst the easiest to use).

962. In the first place, the operator should learn to be very "clean" in all his work, and also be economical in the use of his chemicals (considerable money can be wasted in the misuse of chemicals), as not only must the negative be of good quality, but it must be produced at a minimum cost.

963. The formulae for each of the parts and the order in which they are to be used are as follows:

964. Preparation Of The Glass

Preparation Of The Glass. The glass - which should be carefully selected, and be perfectly flat and free from imperfections - is first immersed in a solution of nitric acid (commercial) for at least twelve hours, then taken out and thoroughly washed with a brush, under running water, next rinsed and flowed twice with a solution of albumen, and afterward placed in a rack to dry.

965. Albumen Solution

Albumen Solution. The solution of albumen is made from the white of one egg, 32 ounces of water, to which is added 10 drops of aqua ammonia. Flow as many plates as you desire with the albumen and place in the rack to dry, when they are ready for collodionizing.

966. Collodionizing The Plate

Collodionizing The Plate. After being thoroughly dried, the glass is now ready to be coated with the collodion solution, which is made differently for producing either half-tone or line work as follows:

967. Collodion Solution For Half - Tone Work

Collodion Solution For Half - Tone Work.

Alcohol .....................

.................32 ozs.

Ether .......................

.................32 ozs.

Cotton (Negative) ..........

................360 grs.

Iodide of Cadmium ..........

................150 grs.

Iodide of Ammonium ........

.................90 grs.

Chloride of Calcium .........

................30 grs.

Chloride of Strontium .......

.................30 grs.

968. Collodion Solution For Line Work

Collodion Solution For Line Work.

Alcohol ....................

..................32 ozs.

Ether ......................

32 ozs.

Cadmium Bromide .........

.................120 grs.

Iodide of Ammonium .......

.................320 grs.

Negative-Cotton ............

....................1 oz.

969. I he glass is now ready for the silver bath, which is made up as follows: