There is another advantage in using the air as a cooling medium. In shallow setting, more surface is exposed and the air, coming in contact with the surface, imparts to it a portion of its oxygen, which mingles with the oils and develops that fine butter flavor so much relished by most and which is a peculiarity of fine butter. Again, slow cooling gives more time for this oxydation to go on, and thus "ripen" the cream for churning without souring it. This leaves all the fine flavor in it, unmixed with flavors resulting from acidification. But, where milk is set deep for creaming--and especially where there is no exposure to the air, as is the case in submerging--no butter flavor is developed, and the cream has to be kept until sour before it is properly oxydized. There is not a full development of butter flavor proper, but development of flavor resulting from the mingling of lactic acid with the oils. But without this exposure and acidification, the butter is insipid and comparatively flavorless. Any subsequent exposure to the air soon throws the butter off flavor, the oxygen mingling with the fats alone while the cream is rising and still sweet. This development of flavor by oxydation is not mere theory; it has been scientifically demonstrated at Cornell University, New York, if not elsewhere, and must sooner or later be generally accepted and butter making proceed on a more rational and certain basis. But it is hard work to get people out of old ruts, or to overcome fixed habits and prejudices. Really scientific butter making, in which every step will be thoroughly understood and deliberately taken, is a thing of the future. It will come in time, and then our descendants will wonder why we were so stupid and slow as not to see and adopt the simplest principles when they were thrust into our very faces. But mind and judgment are matters of growth, the same as everything else in this universe of being. SKIMMING MILK. So many improvements or inventions have been introduced in the setting of milk for cream that the term "skimming" has become almost a misnomer. In both deep and shallow setting, arrangements have been made in several of the patent pans and cans for drawing out the milk from the bottom and leaving the cream. Glass gauges are set in the vessels so that the exact depth of the cream can be seen, and the milk drawn down close to the cream or a small amount of the upper portion of the milk left with the cream. In skimming with a skimmer or dipper, many aim to take the upper portion of the milk, on the theory that the separation is less perfect toward the top than it is lower down. Especially may this be done where a dipper or skimmer without holes is used. It is claimed by some careful experimenters and close observers that this adds to the quantity of butter yielded without deteriorating the quality. WHEN TO SKIM.