THE CHEMISTRY OF COOKERY. 521 



reason why the modern method has superseded this appears to be that 

 the leaven is liable to proceed onward beyond the first stage of fermen- 

 tation, or that producing alcohol, and run into the acetous, or vinegar- 

 forming fermentation, producing sour bread. Another reason may 

 be that the potato mixture above described, which is but another kind 

 of leaven, is more effectual and convenient. 



Dr. Dauglish's method (patented in 1856, 1857, and 1858) is based 

 on the fact that water under pressure absorbs and holds in solution a 

 large quantity of carbonic-acid gas, which escapes when the pressure 

 is diminished, as in uncorking soda-water, etc. Dr. Dauglish places 

 the flour in a strong, air-tight iron vessel, then forces water saturated 

 with carbonic acid under high pressure into this ; kneading-knives 

 mix the dough by their rotation. When the mixture is completed, a 

 trap at the lower part of the globular iron vessel is opened. The 

 pressure of the confined carbonic acid above forces the dough through 

 this in a cylindrical jet or flat ribbon as required, and this squirted 

 cylinder or ribbon is fashioned by suitable cutters, etc., into loaves. 

 The compressed gas expands, and the loaves are smartly baked before 

 the expansive energy of the gas is exhausted. 



The difference between new and stale bread is familiar enough, but 

 the nature of the difference is by no means so commonly understood. 

 It is generally supposed to be a simple result of mere drymg. That 

 this is not a true explanation may be easily proved by repeating the 

 experiments of Boussingault, who placed a very stale loaf (six days 

 old) in an oven for an hour, during which time it was, of course, be- 

 ing further dried ; but, nevertheless, it came out as a new loaf. He 

 found that during the six days, while becoming stale, it only lost one 

 per cent of its weight by di-ying, and that during the one hour in the 

 oven it lost three and one half per cent in becoming new, and appar- 

 ently more moist. By using an air-tight case instead of an ordinary 

 oven, he repeated the experiment several times in succession on the 

 same piece of bread, making it alternately stale and new, each time. 



For this experiment the oven should be but moderately heated — 

 130° to 150° is suflicient. I am fond of hot rolls for breakfast, and fre- 

 quently have them a la Boussingault, by treating stale bread-crusts in 

 this manner. My wife tells me that when the crusts have been long 

 neglected, and are thin, the Boussingault hot rolls are improved by 

 dipping the crust in water before putting it into the oven. This is 

 not necessary in experimenting with a whole loaf or a thick piece of 

 stale bread. 



The crumb of bread, whether new or stale, contains about forty- 

 five per cent of water. Miller says, " The difference in properties be- 

 tween the two depends simply upon difference in molecular arrange- 

 ment." 



This " molecular an-angement " is the customary modem method 

 of explaining a multitude of similar physical and chemical problems, 



