=Fullers Earth.=--About thirty years ago the method of refining lard with fullers earth was first inaugurated, and for years only imported earth from England was thought suitable for this purpose. Deposits of fullers earth, of fair quality, have been discovered in the United States and American fullers earth is today used in some lard refineries. Indications are that with improvements in mining and methods of grinding, and possibly also in the discovery of better beds or layers of this substance, manufacturers will not continue to go abroad for supplies of fullers earth. An explanation of how fullers earth bleaches lard and its kindred fats would be interesting, if anyone knew the exact explanation, but so far there has been no scientific reason given that accounts for this property of this material, therefore no chemical test can be applied to different samples of fullers earth to determine whether they are suitable for refining or not. The only safe test is the practical one of heating a sample together with lard and watching the result of the bleach. Fullers earth is used for bleaching cotton seed oil and other greases and fats which are subjected to the bleaching process. In improving the color of lard it is done at the expense of flavor, and a wholesome odor, which is natural to the lard, is sacrificed in a greater or lesser degree to the advantage of color. The tendency is to make lard white, even though it loses in odor and taste. In compounding lard this is intensified by the general use of tallow. [Illustration: FIG. 152.--FULLERS EARTH KETTLE FOR SMALL HOUSES.] =Bleaching Kettle.=--This can be of a predominant size dependent upon the volume of business. For a moderate business the most suitable dimensions are about six feet in diameter and four feet deep. A sectional view of such a kettle is shown in Fig. 151 and a smaller kettle is illustrated in Fig. 152. It was the practice to use compressed air for agitation so as to mix the fullers earth with the lard. This has been discontinued in the best refineries, as it was found that agitation with air had a tendency to make the lard turn rancid more readily than if agitated by mechanical device.