ORWOCOLOR 73 - Fixing Solution
1. Sodium thiosulfate, anhydrous .................. 120.0 g
2. Ammonium chloride ................................... 80.0 g
3. Water to make ............................................... 1 L

MW(Sodium thiosulfate, anhydrous) = 158.11, so 120g of Sodium thiosulfate anh required ... 81.2g of Ammonium chloride for full reaction. Bingo!