323. Flour, or some other farinaceous article, is, or ought to be, the basis of all thickening's; starch of potatoes, or indeed any other pure starch, is a good substitute for flour. We do not recommend preparations of Carraghan moss, ivory dust, or eggs; they are troublesome, and not at all necessary. A table-spoonful of potatoe or any other starch, such as arrow-root, mixed in two table-spoonsful of cold water, and stirred into soup, sauce, or gravy, &,c. and afterwards simmered, just before serving, will thicken a pint. Flour will also answer the same purpose. In large establishments, the following thickening is generally kept ready prepared; the French call it. roux; it is thus made: Put some fresh butter, if clarified the better, (or some use the skimmings of the pots, clean and not impregnated with vegetables,) into a stew-pan over a clear slow fire; when it is melted, add fine flour sufficient to make it the thickness of paste; stir well together when over the fire, for ten or fifteen minutes, till it is quite smooth and of a fine "yellow-boy" colour. Do all this gradually and patiently, or you will spoil your thickening by getting it burnt, or giving to it a burnt flavour, which will spoil your gravy, etc. Pour it into an earthen pan for use, it will keep for a fortnight; and if, when cold, it is thick enough to be cut with a knife, a large spoonful will be enough to thicken a quart of gravy, etc. Most made dishes, such as sauces, soups, and ragouts, are thus thickened. The broth or soup, etc., to which the thickening is put, must be added by degrees, so as to incorporate them well together. To cleanse or finish a sauce, put into a pint two table-spoonsful of broth, or warm water, and put it by the side of the fire to raise any fat, etc, which must be carefully removed as it comes to the top.

We would strongly recommend mistresses of families, particularly those residing in the country, where potatoes are cheap, to keep a good stock of potatoe starch always by them. If kept dry and from the air, it will keep almost for any length of time. Damaged potatoes will yield starch or mucilage, if raw. It may be made from the old potatoes, when by germination in the spring they have become unfit for the table, or from the refuse of a newly gathered crop in the autumn. The starch will be found extremely useful, not only in a thickening, but also for mixing with wheat flour in making bread, &,c. Starch may be made, and is made, from various vegetable substances, and used as a substitute for corn flour. The following is the mode of making potatoe starch; arrow-root starch and all other starches are made by a similar process:

The potatoes must be carefully washed and peeled, and every speck removed; provide yourself with a number of deep dishes, according to the quantity of starch you wish to make; for every pound of potatoes to be prepared in each dish, put a quart of clear water; grate them into the water on a bread grater; stir it up well, and then pour it through a hair sieve, and leave it ten minutes to settle, or till the water is quite clear; then pour off the water, and put to it a quart of fresh water: stir it up, then let it settle, and repeat this till the water is quite clear. You will at last find a fine white powder at the bottom of the vessel; lay this on a piece of paper in a hair sieve to dry, either in the sun or before the fire; when thoroughly dry, it is ready for use. It is perfectly tasteless, and may be used to thicken melted butter, instead of flour. A great deal of the arrowroot sold in the shops is neither more nor less than potatoe starch. Though we strongly recommend it as effectual and economical for the above purpose, for an invalid it is very inferior in strength and nutricious qualities to the Indian arrow-root starch.