It's Dove dishwashing soap (liquid) and powdered Clorox 2. It's 1 part Dove, 1 part Clorox 2 and 1 part warm water (not hot). It can take 1-3 weeks to remove the stain in this liquid and you need to watch the water level (due to evaporation).
This is a variation on a non-antique linen recipe that is a god-send. That one is 1 c. powdered Cascade dishwashing detergent, 1 c. powdered Clorox 2 and 5 gallons (or a slop sink full) of your tap's hottest water--soaking the clothing overnight and then laundering them in the washer. But this one is too harsh for the antiques.
Thank-you so much, Heather. I have several antique doilies, dresser scarves, etc., that were my Mother's and they are so precious to me that I didn't want to take a chance washing them in anything too harsh. At the same time, I really want to get the old spots and yellowing out if I can.