Dr Colquhoun on the Art of baking Bread, 77 



from the sour dough alone had a taste distinctly perceptible of 

 acidity, and a smell so sour as must have rendered it almost 

 unsaleable, while that which contained the magnesia present- 

 ed not the slightest indications of any kind of sourness, and 

 appeared in all respects an excellent loaf." 



" To vary the experiment, an attempt was made to correct 

 the acidity of the dough after standing twenty-four hours 

 longer in a warm place, and when it had become strongly acid. 

 " Four portions of this dough were now taken, all of which were 

 baked after the usual form, but with this difference in their 

 composition, that one was put into the oven made of the same 

 dough just as it stood ; a second had four grains, and a third 

 eight grains of the carbonate of magnesia kneaded up with 

 them, and to the fourth was added sixteen grains of the com- 

 mon crystallized carbonate of soda. The first loaf, when baked, 

 possessed, in a very rank and strong degree, both a taste and 

 smell of acidity. In the second, the acidity remained faintly 

 perceptible, especially in the smell. In the third, the loaf had 

 no acid or other disagreeable property whatever. In the 

 fourth, there was no acid taste, but a slightly acid smell. 1 ' 



" These results appear quite decisive. For thus the exhi- 

 bition of eight grains of the carbonate of magnesia to five ounces 

 of dough, or about thirty-two grains to the pound, which is 

 about fifty-two grains to the pound of flour, proved amply 

 sufficient to correct an acidity which had been allowed to pro- 

 ceed to an extreme hardly ever known in practice. And in- 

 deed in the great bulk of instances a much smaller quantity 

 would be found completely sufficient ; so that, in all probabi- 

 lity, three ounces of carbonate of magnesia to every 100 

 pounds of flour would be found to serve the purpose, pro- 

 vided a due incorporation of the magnesia were effected 

 though out the substance of the bread." 



In the second part of this interesting essay, published in 

 the Annals of Philosophy for October, Dr Colquhoun makes 

 some remarks on the processes for introducing an elastic fluid 

 into dough, which has not undergone the panary fermentation. 

 One of the methods which have been recommended for this 

 purpose, namely, the use of water charged with carbonic acid 

 gas, was found quite ineffectual as well for exciting fermenta- 



