As fast as brought in, the milk should be run through a hair sieve. This, and also the vessels with which the milk comes in contact, must be kept scrupulously clean by the aid of constant scalding, to be followed by rinsing with cold water, and drying in the air. The milk is exposed in the pans for varying periods in order that the globules of fat may have an opportunity of separating from the milk and floating on the surface. This process is now very commonly replaced by the use of a hydro-extractor, in which centrifugal action breaks up the milk into cream and “skim milk” without any need for waiting. According to the older practice the milk is left to stand for a considerable time, but no advantage is gained by exceeding 24 hours; in fact the best authorities say that it should be skimmed before the surface begins to look wrinkled, as this appearance is a symptom of incipient putrefaction. Large shallow perforated tin ladles are used for removing the cream, which should be carefully deposited, without splash, in white stoneware jars holding 2 to 12 gal., according to the size of the dairy. Common glazed earthenware is to be avoided on account of injurious chemical action. Skimming should be done twice daily, and each time an addition of cream is made to the jar the whole contents should be well but gently stirred with a stoneware spoon. The jars should be covered with gauze to exclude insects. In some dairies skimming is avoided by the simple plan of having a hole in the bottom of the milk dish by which the milk is drawn off, leaving the cream undisturbed. Butter consists of the fatty portion of the milk, which is separated by the process known as “churning,” the object of which is to rupture the envelopes which hold the fatty matter. The bulk of this fatty matter resides in the cream. Butter may be “made” by churning either the milk or only the cream; and these may be either in a sweet or sour (“lappered”) state. The most general practice is to churn the cream alone in a lappered condition. For this reason the cream is set to ripen in stoneware jars for several days, averaging about 3 days in summer, and 5 or 6 in winter, preferably with occasional stirring. It is the general opinion that to get the best butter, the operation of churning should be comparatively slow, from ¾ hour to 2 hours--an hour being a fair average, varying, however, according to the season; the operation being much more tedious in winter than in summer. After the butter is separated from the cream, the buttermilk remains, containing the casein, salt, and sugar present in the original cream, though a portion of these is taken up with the butter. The greater the proportion of casein left in the butter, the poorer is the latter in quality, and the more readily will it become rancid. Commenting on Jenkins’ pamphlet, ‘Hints on Butter-making,’ the _Field_ recently published the following remarks:--