264 Dr, Colquhoim*s Essay [Oct. 



»'<It is generally supposed, that after passing through the oven, 

 the carbonate of ammonia has been so completely dissipated by 

 the heat, as to leave no traces behind of its having ever been 

 present in the bread, except a light tinge of yellow colour, and 

 a slight, unpleasant flavour, which latter quality is easily 

 disguised, in all confectionary, by the use of a httle sugar. 

 But in addition to these vestiges, a small portion of the salt 

 itself almost constantly lurks in the substance of the bread ; for 

 it has very generally a strong odour of ammonia when taken 

 fully baked from the oven; and, though for the most part it 

 becomes inodorous when cold, yet on being again heated, the 

 presence of ammonia is again indicated by the smell. It can 

 only happen, however, in cases of the most extreme carelessness 

 that any such quantity shall remain behind, as may tend either 

 to affect sensibly the flavour of the bread, or to prove injurious 

 to even a delicate constitution. 



Nothing can be simpler in its operation, than the sesqui- 

 carbonate of ammonia, as to the mode in which the dough pre- 

 pared with it becomes filled with a large supply of elastic fluid 

 as soon as it is placed in the oven. Without dwelling any 

 longer upon it, therefore, let us proceed to consider another 

 mode that has been proposed for gasifying bread, and which, 

 perhaps, derives its principal claim to regard from the circum- 

 stance, that it has gained the support of more than one chemist 

 of eminence ; for it has hardly yet been found of much practical 

 efficacy, nor does it appear likely soon to become so. 



The process alluded to, is that of impregnating the dough 

 artificially with free carbonic acid gas, at the very commence- 

 ment of the baking process, when the flour is originally mixed 

 up with water ; and it has been supposed that the carbonic acid 

 thus introduced will have the effect, in consequence of the 

 expansion which it suffers in the oven, of communicating a 

 sufficient degree of vesicularity and lightness to the bread. 



The possibility of expanding dough by saturating it in this 

 manner with carbonic acid gas, has been long asserted by various 

 authorities of a more or less questionable description ; but Mr. 

 Edlin may be said to have been the first person who brought it 

 forward, in a formal manner, into general notice. In his Treatise 

 on the Art of Bread-Making, p. 56, it is stated unquahfiedly by 

 this author, as the result of repeated trials, that if warm recent 

 dough and some flour be kneaded with a saturated aqueous 

 solution of carbonic acid gas ; and if the mass of dough thus 

 prepared be placed in a warm situation for about half an hour, it 

 will expand, exactly like dough in a state of regular fermenta- 

 tion ; and that if it be now baked in the oven, it will yield an 

 excellent light porous bread, not distinguishable in quality from 

 that obtained with the assistance of yeast. He quotes also in 

 ^pport of this, certain accounts which have been published of 

 the employment of various mineral springs in baking bread j 



