22 THE MICROSCOPE. Feb. 



up in the art ; they baked cakes and loaves of various 

 shapes and varieties, using several kinds of flour, which 

 they flavored with aromatic ingredients. From these the 

 art spread over Europe, the people of the several coun- 

 tries taking to it eagerly, except those in the extreme 

 north, and even to this day it is carried on sparingly there. 



Many changes have come in the manipulation, and 

 attempts have been made to use other methods for light- 

 ening the bread. Where chemicals have been introduced 

 into the dough to generate the gas in it, the bread must 

 be eaten while fresh to be palatable; and aeration gives 

 a tasteless bread. But taken all in all, we are uot so far 

 ahead of the ancients in the matter of fermenting the 

 dough. In the matter of preparing the flour great 

 progress has been made. 



Fermentation consists, essentially, in the breaking up 

 of chemical'compounds, the molecules being separated and 

 recombined into more stable compounds. The fermen- 

 tation is always accompanied by a rise in the temperature ; 

 this can be noted easily by plunging a thermometer into 

 rising dough, or a fermenting liquid. The fermentation 

 in bread is the same as that in beer and other fermented 

 beverages — an alcoholic one. It consists in tlie breaking 

 up of the molecules of sugar into CO^, alcohol, succinic 

 acid, glycerine, and a number of bye products, which vary 

 in quantity and nature with the kind of yeast used, and 

 the conditions under which growth has taken place. 



There are other ways of fermenting bread than by means 

 of yeast. The old method being to mix together flour, 

 water or milk, and mashed potatoes, the potatoes being 

 a good food for microorganisms, the dough being then 

 allowed to stand until a spontaneous fermentation had 

 taken place. This method is still })ractised in country 

 places where yeast is difficult to obtain, and is the same 

 process as the leavening of the ancients. A quantity of 



