The whole is then intimately kneaded with more water for upwards of an hour. The dough is cut into pieces with a knife, and penned to one side of the trough; some dry flour is sprinkled over it, and it is left in this state for about four hours. It is then kneaded again for half-an-hour. The dough is now cut into pieces and weighed, in order to furnish the requisite quantity for each loaf. The loaves are left in the oven about two hours and a half. When taken out, they are carefully covered up, to prevent as much as possible the loss of weight.[43] The following account of making a sack, of five bushels of flour into bread, is taken from Dr. P. Markham's Considerations on the Ingredients used in the Adulteration of Bread Flour, and Bread, p. 21: 5 bushels of flour, 8 ounces of alum,[44] 4 lbs. of salt, 1/2 a gallon of yeast, mixed with about 3 gallons of water. * * * * * lbs. The whole quantity of bread-flour obtained } from the bushel of wheat, weighs } 48 lbs. Fine pollard 4-1/4 Coarse pollard 4 Bran 2-3/4 ------ 11 -- The whole together 59 To which add the loss of weight in } manufacturing a bushel of wheat } 2 -- Produces the original weight 61 -- The theory of the bleaching property of alum, as manifested in the panification of an inferior kind of flour, is by no means well understood; and indeed it is really surprising that the effect should be produced by so small a quantity of that substance, two or three ounces of alum being sufficient for a sack of flour. From experiments in which I have been employed, with the assistance of skilful bakers, I am authorised to state, that without the addition of alum, it does not appear possible to make white, light, and porous bread, such as is used in this metropolis, unless the flour be of the very best quality. Another substance employed by fraudulent bakers, is subcarbonate of ammonia. With this salt, they realise the important consideration of producing light and porous bread, from spoiled, or what is technically called _sour flour_. This salt which becomes wholly converted into a gaseous state during the operation of baking, causes the dough to swell up into air bubbles, which carry before them the stiff dough, and thus it renders the dough porous; the salt itself is, at the same time, totally volatilised during the operation of baking. Thus not a vestige of carbonate of ammonia remains in the bread. This salt is also largely employed by the biscuit and ginger-bread bakers.