Chrome alum hardening fixing bath recommended for hot weather processing. Also known as Ansco 202.

Pour 1 part Solution B into 3 parts Solution A, whilst stirring A rapidly.
Solution A
Sodium thiosulphate320
Sodium sulfite anhydrous
Water to make
Solution B
Chromium potassium sulphate60grams
Sulphuric acid8mililiters
Water to make1liter

This formula, when freshly mixed, is especially recommended for use during hot weather, but it rapidly loses its hardening properties, with or without use. Useful life is only 1 day.

Scum which may form on the surface of the negative when an old bath is used is removable by swabbing with cotton-wool before the negative is dried.