I madr the stock solutions at 100gms potassium ferricyanide to 1 liter of water and 33gms of potassium bromide to 1 liter of water per Katchel. From this I make a working stock of 100ml of ferricyanide solution and 100ml of bromide solution to 800ml of water. From this I start with 20ml to 50ml per 1 liter of water and adjust as needed to get contraction I want. Am I reading Katchel's paper correctly?