The official name is "Harvey's 77 Panthermic" and it is a proprietary film developer that utilizes glycerin and p-phenylenediamine (ppd). The panthermic reference means that it can be used at a wide range of tempratures from 55 degrees to 100 degrees F but is best at about 75 degrees F. If is a replenishing developer that means that after a certain amount of film has been developed, a portion of the developer can be dumped out and a similar volume can be added to bring the developer back to its original developing strength. I can be kept with replenishment for an extended period of time in large developing tanks or poured into trays for use. There is an article on this developer at unblinkingeye.com.
Originally Posted by chrobry