TUBEROUS ROOTS, AND GRAIN. 347 



the former, in contact with dough to excite it to ferment, 

 and this may be done either with yest or leaven. 



Caroline. It is, then, a sort of contagion which these 

 bodies communicate to the dough ; but is it not surprising 

 that it should render the bread light and wholesome, in- 

 stead of turning it sour ? 



Mrs. B. Were the fermentation of the dough not in- 

 terrupted by baking, it would become sour, as that por- 

 tion does which is reserved for leaven. The fermenta- 

 tion of bread is by some chemists considered as a com- 

 mencement of the acetous fermentation. There must, 

 however, I conceive, be some difference between these 

 processes, as in the regular succession of fermentations, 

 the acetous is always subsequent to the vinous ; and 

 bread is so perfectly insipid that there is no reason to 

 suppose it has undergone the latter. 



Emily. Yet wheat is, I suppose, like other kinds of 

 grain, susceptible of undergoing the vinous fermentation. 



Mrs. B. Certainly ; alcohol may be obtained from 

 all kinds of grain. There are four species of wheat. 



First. The common wheat, whose ears are erect, and 

 its grains obaque and obtuse. 



Second. The Triticum turgidum of Limoges, which the 

 French call Gros bled, whose ears are thicker and larger ; 

 it contains less gluten, and, consequently, is not so well 

 calculated for bread ; but is much used on the Continent 

 to thicken soup or porridge. This wheat, if cultivated in a 

 very rich soil, produces a variety called miraculous wheat, 

 the ears of which are branching from the abundance of 

 their produce. 



Third. Bled dur, or hard wheat : the grain is semi- 

 transparent ; it has still less gluten than the preceding : 

 it is of this species that macaroni, vermicelli, and all the 

 Italian pastes are made : it requires a dry soil and a warm 

 climate, and thrives best in the southern parts of Europe. 



Fourth. Polish wheat : it grows very plentifully in Po- 

 land, and is thence exported to other countries ; but be- 

 ing of inferior quality, it is little cultivated elsewhere. 



1879. If the fermentation of dough were not interrupted by baking 

 what would be the consequence'? 1880. What is the opinion on the 

 subject of fermentation in bread, and why is this opinion thought errone- 

 ous'? 1881. Can alcohol be obtained from all kinds of wheat! 1882. 

 What is the first of the four species of wheat'? 1883. What is the second, 

 and what is said of it under different circumstances of culture 1 ? 1884. 

 What is the third and what is made from ill 1885. The fourth, and 

 what is said of thatl 



