I m the one who was given the 2 lb. compressed yeast and asked here for usage advice. I'm glad I didn't toss it.  I proofed a bit of it, started half a loaf, doubled the amount of the powdered yeast measurement I'd been using - and mirabile dictu!  It turned out fine. Nice rise and no empty hole under crust either, which had become a recent nuisance - maybe cuz my old batch of powdered yeast was gettin' on in years? I have been turning out decent loaves since that experiment.  I use some of the warm water normally called for in a recipe,  add the yeast to it and get it melted down, so to speak, then dump into ABM at end of ingredient. Thanks to those who encouraged me to try it -  my frugal bone thanks you too.  The friend who sent it is thrilled that the loaves are edible, saved me money and I guess I have a yeast source for life.  He got it from a Portuguese bakery.  Even mailng it, freezing it and thawing it didn't kill it.