In warm weather, or warm climates, the following alum fixing bath may be used in place of the plain hypo and water :-

A

Water..............................

...... 96 ounces

Hypo.......................................

...... 2 pounds

B

Sulphite Soda (Anhydrous), 4 ounces, or, if in crystals, double the amount.

Powdered Alum....................

...... 6 ounces

Citric Acid.........................

1 ounce

Water..............................

...... 64 ounces

When both solutions are thoroughly dissolved, pour B into A slowly, while stirring rapidly.