USE OF LEAVEN. 183 



it, but it will be irregular and very uncertain. If, 

 however, a small piece of this sour dough is taken and 

 thoroughly kneaded up with a large lump of fresh 

 dough, the whole of the latter will very soon enter 

 into a uniform state of fermentation; and if a 

 small piece of this is set aside for the next baking, 

 it will be in a fit state for use by the time that it is 

 required. 



443. The leaven may be formed either of the same 

 kind of flour as the bread is intended to be made with, 

 or any other sort; it is most commonly the custom to 

 employ bean, pea, or some similar flour, which passes 

 very easily into fermentation, or at least to mix a 

 portion of it with the flour used in forming the leaven. 

 When well mad^, leaven may be kept fit for use for 

 week§ and months, and by adding a portion of dough 

 to the leaven as large as that removed for the use of 

 the bread-maker, the stock of leaven is always kept 

 up. 



444. In this country, however, the use of leaven is 

 almost wholly superseded in favor of yeast. This 

 substance can usually be obtained from a neighbor- 

 ing brewery, and a small quantity of it mixed up with 

 the dough, brings it rapidly into the required state 

 of fermentation, without communicating to it the sour 

 taste which leaven always gives to bread. In many 

 parts of Europe, however, and when yeast cannot be 

 had, all the bread is made with leaven. 



445. Leaven added to dough excites in it a true 

 alcoholic fermentation, but it also produces a portion 



