324- Dr. R. D. Thomson on the 



The author has succeeded in forming a wholesome and 

 palatable bread by the employment of ammoniacal alum and 

 carbonate of ammonia or soda as a substitute for yeast. In 

 this process the alum is destroyed by the heat; the bread is 

 vesicular and white, and rises, according to the judgement of 

 the baker, as well as fermented bread. It is obvious that none 

 of the ingredients added can affect the integrity of the consti- 

 tuents of the flour, an occurrence which possibly may happen 

 in the preparation of bread by the common process of fermen- 

 tation, as has been shown, even to the azotized constituents. 

 The disadvantage of such a deterioration is sufficiently evident 

 if we view these principles as the source of nutrition in flour. 

 The first chemist who examined flour with any successful 

 result was Beccaria of Bologna, who detailed his experiments 

 in a communication to the Academy of that place, in 1742. 

 " To endeavour to know oneself," observes he, " is to satisfy 

 the obligation which the oracle of Apollo imposes on every 

 one— to know oneself- — for, if we except the spiritual and im- 

 mortal part of our being, and if we only take into considera- 

 tion our bodies, is it not true that we are composed of the 

 same substances which serve as our nourishment?*" From 

 his subsequent remarks it is obvious that he considered the 

 glutinous part of flour to be peculiarly of an animal and the 

 starch of a vegetable nature; for when distilled, the gluten, he 

 says, affords principles similar to those of all animals, while the 

 starchy part yields products similar to those of all vegetables. 

 We have thus, in the sagacious observations of Beccaria, the 

 origin of the present idea, that animals are principally formed 

 from the glutinous or albuminous principle of vegetables. 

 The mechanical method of analysis which the Italian chemist 

 discovered is the basis of our present process, and it affords 

 undoubtedly the only test which we possess of the compara- 

 tive value of flour as a baking material by the fermented plan. 

 But it fails to inform us of the absolute nutritive value of flour. 

 The most correct method of accomplishing this object is by 

 the determination of the amount of azote present in the flour, 

 by converting that element into ammonia, and precipitating 

 by bichloride of platinum. In the following analyses, to de- 

 termine the comparative values of different kinds of bread and 

 flour, this process has been used, and the nutritive principles 

 calculated by considering them to contain on an average 16 

 per cent, of azote, according to Dumas. 



I. Naumburg. Bread with a brown aspect. This town is 

 situated in the south of Prussia, on the river Saale, in the 

 neighbourhood of a fertile country. The specimen was ob- 

 * Collection Academique, vol. x. p. 1, 



