The above description applies only to the mode of baking as practised in London. No doubt, slight differences exist in different countries. The French loaf, which is baked in a pan, requires obviously a different process from the English loaf; and it is kept a longer time in the oven.
Alum is not added by all bakers. The writer of this article has been assured by several bakers of re spectability, both in Edinburgh and Glasgow, on whose testimony he relies, and who made excellent bread, that they never employed any alum. The rea son for adding it, given by the London bakers, is, that it renders the bread whiter, and enables them to sepa rate readily the loaves from each other. This addition has been alleged by medical men, and is considered by the community at large, as injurious to the health by occasioning constipation. But if we consider the small quantity of this salt added by the baker, not quite 5i grains to a quartem loaf, we will not readi ly admit these allegations. Suppose an individual to eat the seventh part of a quartern loaf a-day, he would only swallow eight-tenths of a grain of alum, or, in reality, not quite so much as half a grain ; for one-half of this salt consists of water. It seems ab surd to suppose that half a grain of alum, swallowed at different times during the course of a day, should occasion constipation.
The method of baking by means of leaven was this: A quantity of flour ia made up into dough with wa ter ; this dough being set in a warm place, is left for about thirty-six hours. Miring that period it swells considerably, and becomes of a thinner consistency. In short, it undergoes a species of fermentation. It has now acquired a peculiar smell, and a disagree able sour taste, and is the substance known by the dame of leaven. If this substance be mixed with a quantity of fresh dough, it occasions the whole to undergo a speedy fermentation, and to swell precise ly in the same manner as dough mixed with yeast. Bread skilfully baked in this manner is not inferior to yeast bread ; but when unskilfully managed, it has a sour taste, and contains .a quantity of acetic acid. According to the experiments of Mr Edlin, a pound of flour, when converted into leaven, con tains as much acetic acid as requires 40 grains of carbonate of potash to neutralize it. If by carbo
nate he means (as is probable) bicarbonate a pot ' ash, 40 grains of it contain 21 grains of potash, which requires for saturation 221 grains of acetic acid.
Pliny informs us that yeast in his time was em ployed in Spain and Gaul as a ferment of bread. Gallia et Hispania frumento in potum resoluta, qui bus dirintus generibus, spunta its concrete pro fru mento utuntur. Qua de cause levidr illis quam ceete •is penis est. (Natur. Hut. lib. xviii. c. 7.) From this passage we see that the Romans employed leaven to raise their bread, but that they were sensible of the superiority of yeast. Leaven, however, made its • • way both into France and Spain, and was universally employed in the manufacture of bread till towards the end of the seventeenth century, when the bakers of Pa cis began to import yeast from Flanders, and to em ploy it pretty generally as a substitute for leaven. We. have here a striking instance of the blindness and ob stinacy of the learned and the powerful, and the readi ness with which they are disposed to arm themselves against all alterations and improvements. The bread by this substitution was manifestly improved both in appearance and in flavour. This variation excited at tention ; the cause was discovered the faculty of medicine in Paris declared it prejudicial to the health; the French government interfered, and the bakers were prohibited, under a severe penalty, from em ploying yeast in the manufacture of bread. But it • is in vain for governments, colleges, and universities, to oppose themselves to those improvements which take place in the arts and manufactures essential to civilized society. The ingenuity and perseverance of self-interest is proof against prohibitions, and con trives to elude the vigilance of the most active go vernment. The laws of Queen Elizabeth, hoirever tyrannical and absurd, did not prevent the introduc tion of indigo as a dye-stuff into England. Neither did the authority of Louis the Fourteenth, nor the decision of the physicians, deter the Parisian bakers from persisting in their improved mode of making bread. The yeast in Flanders was put into sacks, the moisture was allowed to drop out, and in this comparatively dry state it was carried to the capital of France.