Scientific Lectures. Ill 



have said, the ghiten having become semi-fluid. Ahim has been and 

 is Largely used to prevent this change. It stiflens the ghiten. It is 

 possible, also, that it serves to neutralize the ammonia that attends 

 saccharine fermentation, and prevent the darkening afl:ect of the 

 alkali on the bread. Sulphate of copper has been used — a more 

 aetive poison. Liebig proposed the use of lime-water, wliich is harm- 

 less, and accomplishes the same end of stiffening the gluten. There 

 is the habit of having the dough wait on the oven, whereas the oven 

 should be hot and the dough in proper condition at the same instant. 

 Then there is the weary brain which may fail to respond to the neces- 

 sities of the loaf, if it is to be good. All or most of these difficulties 

 attend on achieving with yeast the single quality of cellular structure 

 in the loaf. 



Substitutes fok Ferment.. 

 The chemist, satisfied of this truth, turned his attention, long ago, 

 to affecting this result by more purely chemical means. Half a cen- 

 tury since, and more, bicarbonate of soda w^as intimately mixed with 

 flour, and this mixture wet into dough with diluted hydrochloric acid. 

 This gave carbonic acid to puff up the dough and common salt to 

 flavor the bread. Dr. AVhiting, of England, worked to improve this 

 process, and Dr. Thompson estimated the saving of flour by avoiding 

 the loss due to fermentation at from eight to ten per cent. Mr. 

 Sewall, in 1848, mixed one per cent of strong hydrocliloric acid with 

 flour, and an equivalent of bicarbonate of soda. This mixture was a 

 self-raising flour, which would keep for some days. Liebig has 

 recently proposed these ingredients to improve the black rye and 

 wheat bread of Germany. Long ago, sour milk (lactic acid) and 

 allcaline carbonates were used in this country to make quick bread 

 and biscuit. There was a difliculty in this mode, in that the sour 

 milk was not always uniformly acid, and there was a chance of an 

 excess of alkaline, which discolored tlie bread. Many years since, 

 tartaric acid was used, and more recently cream tartar — another form 

 of tartaric acid — ^has come into extensive use as a substitute for the 

 muriatic or hydrochloric acid. These acids all act to withdraw the 

 alkali from the carbonate, and liberate carbonic acid. This formula 

 will illustrate the action of the acid : Hj^drochloric acid plus carbonate 

 of soda equals chloride of sodium (common salt) plus carbonic acid. 

 Tartaric acid would give tartrate of soda and carbonic acid ; and 

 lactic acid, lactate of soda and carbonic ticid. Some of these forms of 



