How to Make a Dry Yeast That Lasts

In the 1940s Fleishmans and Lissaf developed active dry yeast a yeast that is a packet of what looks like crystals or granules. It can just sit dormant and then be activated by adding hot water. The temperature of the water was important because if it's too hot it doesn't, kills them but if it'sToo cold doesn't activate them so they're a little bit fussy.