The cistern is again filled with water as before, the hopper replenished with potatoes, and thus the grinding and washing away of the starch is alternately performed: this variation in the process affording the man an agreeable change from the labour of turning the mill. It is advisable to use two tall tubs like that already described, and to employ them alternately; which will afford sufficient time for the starch to settle at the bottom of each in a solid cake, while the process is being continued with the other tub. About four inches above the bottom of each tub there should be a stop-cock to draw off the supernatant liquid, which is of a reddish brown colour. The starch should, next be removed from the bottoms of the tubs, (as it is inclined in warm weather to undergo very soon the acetous fermentation, whilst wet, with the coloured water deposited between its particles,) and placed in large glazed pans, wherein it should be washed or stirred up again with fresh water, and allowed to settle again in solid cakes; and this operation should be repeated until the water runs off colourless, which will usually be at the third or fourth time of drawing off. The starch then settles quickly into a firm and beautifully white cake.

It has next to be dried, which is preferably done in the open air, or exposed to the rays of the sun, in a situation free from dust. The mass should be made into lumps with the fingers, and spread out on rectangular frames of wood, over which is stretched any cheap cloth: these, from their form, are very portable, and stand well upon one another, like the frames used by glue boilers for drying their manufacture. When thoroughly dry, it may be stowed away into casks; and if kept unexposed to damp, may be preserved good for a century. In constructing an apparatus for conducting this manufacture on a large scale, many improvements on the foregoing might be made to expedite the work and facilitate the labour, which are too obvious to need our entering further into the subject. It is, however, due to Mr. Whately, of Cork, to observe that that gentleman had invented a machine very similar to the foregoing, some time previous to its publication, but unknown to the author. The difference between the two machines is quite immaterial, excepting that in Mr. Whately's the grinding cylinder works out of water, which renders it liable to clog up, - an effect which is prevented by the arrangement of the other. In a communication made by Mr. Whately to the Society of Arts, (who presented him with their honorary gold medal for the invention,) he states, that " it is capable of the most satisfactory proof that the same quantity of land will yield above one-half more of farina, or flour, where potatoes are cultivated, than if the same quantity of land was applied to the production of wheat." He further states, " l have proved from experiment, that 2,619 lbs. of pure farina, or flour, may be produced from an acre of land planted with potatoes, and only 1,600 lbs. of flour from an acre of wheat. It will therefore be obvious, that if we can apply this great excess to the same purposes as the flour of wheat, the advantages arising from it will be of the greatest importance to the community." It is, besides, well known that many poor light soils, which are considered unfit for the cultivation of wheat, will produce good potatoes abundantly. The cost of producing potatoe flour from the root, Mr. Whately estimates at only half that of obtaining the flour from the wheat In the introduction of a small portion of potatoe flour in the manufacture of sea-biscuit, it is said the quality is materially improved, and that they will keep good for a much longer period of time; and it may be fairly urged, that if potatoes in the gross improve (as it is generally admitted they do) the quality of wheat bread, that they must be still more beneficial when deprived of the refuse matter they contain.

This article is, nevertheless, considered legally as an adulteration of bread, as well as many others, some of which we shall proceed to notice. The most common sophistication in bread is alum. Some writers state that as much as 4 oz. are put into every quartern loaf by the public bakers; but bread containing so large a quantity could not be eaten without serious constipation. From the best information afforded to us, we are inclined to believe the quantity of alum varies with the quality of the flour, the worst flour receiving the most alum to improve the colour; and that the quantity put to a sack of flour (though it varies from 4 oz. to 4 lbs.) is usually about 2 lbs.; and as this will assign to each 4 lb. loaf nearly 1/4 oz., it is very probable the before-mentioned statement of 4 oz. to each loaf arose from an uncorrected error of the press. It has been asserted that bones burned to whiteness, and ground to an impalpable powder, are used to adulterate thirds flour; this we trust, however, is a very rare occur rence. Chalk and whiting, in small quantity, are also, it is said, sometimes mixed with flour.

Salt, although a necessary ingredient in bread, is sometimes added to such an excess that it becomes an adulteration; the object attained by it is the causing the bread to retain a portion of the water which, without it, would be evaporated in the process of baking. If bread contain an unusual proportion of starch, it absorbs and retains more water from that cause. Such bread, therefore, is deficient in solid matter, and is technically termed hungry bread, as an equal bulk and weight does not satisfy the appetite like bread which holds less water. The bakers prefer flour that has been made about three months, or such a mixture of old and new flour as will make an equivalent. Weak inferior flour requires the dough to be made up as dry as possible. If the usual quantity of water required for the best flour be used, there is a liability to the fermentation running into the acetous stage, which of course renders the bread sour. In all cases, if the dough has been made too soft, it should be cooler than usual, otherwise the high heat of the oven quickly forms a crust imperviable to vapour, and thus locks up the water in the bread. Bread in this state is very common amongst the home-made, for want of due experience in the operator.

In the employment of flour made from wheat that has undergone germination, it becomes necessary to have recourse to some extraordinary means to render the bread light. Mr. E. Davy, who made many experiments with a view to determine the best remedy for such malted flour, ascertained that the carbonate of magnesia of the shops, when well mixed with the new flour, in the proportion of from 20 to 40 grains to 1 lb. of flour, materially improves it for the purpose of making bread. Loaves made with it rise well in the oven; they are light and spongy, and keep well. To the worst flour as much as 40 grains may be added to 1 lb. of flour. Care should be taken to mix them intimately together. When too little yeast has been added to the dough, the fermentation is slow and incomplete; when it has been added in too great a quantity, the fermentation becomes too rapid, and renders it liable to sourness; to remedy which, Mr. Chaptel has recommended the kneading up some carbonate of potash with the dough, which neutralizes the excess of acid. Dividing the dough into small masses, and exposing it to the air, also has a tendency to check the fermentation.

Under the several heads of Corn, Dough, Mill, Oven, etc. a variety of improvements in the mechanism and processes of making bread will be found.