Thicken two quarts of water, with fine flour about three spoonfuls; boil half an hour, sweeten with near half a pound of brown sugar; when near cold, put into it four spoonfuls of fresh yeast in a jug, shake it well together, and let stand one day to ferment near the fire, without being covered. There will be a thin liquor on the top, which must be poured off, shake the remainder, and cork it up for use. Take always four spoonfuls of the old to ferment the next quantity, keeping it always in succession.
An half peck loaf will require about a gill.
Boil one pound of potatoes to a mash, when half cold add a cupful of yeast, and mix it well. It will be ready for use in two or three hours, and keeps well.
Use a double quantity of this to what you do of beer yeast.
To take off the bitter of yeast, put bran into a sieve, and pour it through.
When you have plenty of yeast begin to save it in the following manner; whisk it until it becomes thin, then get a large wooden dish, wash it very nicely, and when quite dry, lay a layer of yeast over the inside with a soft brush; let it dry, then put another layer in the same manner, and so do until you have a sufficient quantity, observing that each coat dry thoroughly before another be added. It may be put on two or three inches thick, and will keep several months; when to be used cut a piece out; stir it in warm water.
If to be used for brewing, keep it by dipping large handfuls of birch tied together; and when dry, repeat the dipping once. You may thus do as many as you please; but take care that no dust comes to them, or the vessel in which it has been prepared as before. When the wort be set to work, throw into it one of these bunches, and it will do as well as with fresh yeast; but if mixed with a small quantity first, and then added to the whole, it will work sooner.