The recipe from the book is:

Water at 52C, 750 ml
Sodium sulfite, 200 grams
Sodium bisulfite, 50 grams (optional for paper)
Water to make 1 liter

This makes stock solution. To make a working-strength HCA solution, dilute 1 part stock to 9 parts water. The book is good, and you can find it here: http://www.amazon.co.uk/The-Darkroom...dp/0240810554/

I have both the 2nd and 3rd editions. I would be happy to sell the 2nd edition, PM if interested.