Hyposulphite of soda is generally considered to be the most suitable
fixing agent for negatives, although some prefer cyanide of
potassium. [p036]
The hyposulphite, however, is the safest, both for the plate and for
the operator. One pound of hyposulphite of soda to a gallon of water
will make a solution of a suitable strength to clear a negative as
rapidly as is necessary, and it should be contained in a flat dish.
When from much use the fixing solution becomes muddy, it should be
thrown into a suitable receptacle for liquid wastes, as it is rich
in silver.
Leave the negative in the fixing solution until all the iodide of
silver is dissolved from the film, and no trace of the yellowish
deposit can be seen by transmitted light.
When the negative is thoroughly cleared, if it is found that it
lacks density or, in other words, is not intense enough, wash it
very carefully to free it from every trace of the soda solution, and
then proceed to strengthen it in the following manner: