With correct exposures and the quick method of after treatment to be given it is evident that a time method of development, whether in a tray with the machine or in a tank, is ideal. It should be unnecessary to add that great cleanliness should be observed in all work. It is taken for granted that the reader is already acquainted with the ordinary process of devel oping and finishing a negative and as published formulas are so abundant it is not deemed neces sary to include more than a mere outline of this practice.
Fixing. — When development is finished the negatives should be well rinsed in clean water and passed to the hyposulphite of soda bath which preferably should be made fresh for each batch of negatives. For the fresh bath the author recommends one part of powdered hypo in two parts of water, estimated according to the volume of each rather than the weight. The powdered hypo is recommended only to save time and bother as it dissolves almost immediately by slight stirring. Once the nega tives are well saturated by this bath the usual light no longer affects them. They should re main in the fixing bath twice as long as is re quired to take away the creamy color from the back. Some agitation in this bath is advisable and when several films are treated together they must be moved constantly during the entire time even though they appear to be fixed, for the future permanency of the negatives depends upon thorough fixing, especially when they are to be treated afterwards by reduction or intensification. The author has at times used
the acid fixing bath according to the standard formula and followed it by reduction and inten sification (after 2 or 3 changes of water) without any stains or other evil results. The bath has never been used however more than three times without renewing. The importance of using a fresh hypo bath cannot be overestimated.
When fixation is complete is the time for care ful inspection in appropriate light to determine whether any of the negatives should be reduced or intensified. In actual practice the author frequently has from 10 to 20 exposures without one needing any after treatment. Should any need reducing, however, either locally or gen erally, the work is taken up when the negatives have been removed from the hypo to the first water. Should none require either reduction or intensification, however, they should be given 8 to 10 changes of water, or better still if convenient, at least half an hour in running water. When washed they are placed to dry free from dust. Should any require after treat ment, however, all should be left in the first water after fixing and the work should be pro ceeded with as explained in the section on reduction which follows.