To prepare oats for food, the husk, which is wholly indigestible in character, must be thoroughly removed.  To accomplish this, the grain is first kiln-dried to loosen the husk, and afterward submitted to a process of milling.  Denuded of its integument, the nutritive part of the grain is termed groats; broken into finer particles, it constitutes what is known as oatmeal; rolled oats, or avena, is prepared by a process which crushes the kernels.  Oatmeal varies also in degrees of trituration, some kinds being ground much finer than others.  The more finely-ground products are sometimes adulterated with barley meal, which is cheaper than oatmeal and less nutritious.  The black specks which are sometimes found in oatmeal are particles of black oats which have been ground in connection with the other.

Oatmeal lacks the tenacity of wheaten flour, and cannot, without the addition of some other flour, be made into light bread.  It is, however, largely consumed by the inhabitants of Scotland and the north of England, in the form of oatcakes.  The oatmeal is mixed with water, kneaded thoroughly, then rolled into very thin cakes, and baked on an iron plate or griddle suspended over a fire.  So much, however, depends upon the kneading, that it is said that the common inquiry before the engagement of a domestic servant in Scotland, is whether or not she is a good kneader of oatcakes.

The most common use of oatmeal in this country is in the form of mush or porridge.  For this the coarser grades of meal are preferable.  For people in health, there is no more wholesome article of diet than oatmeal cooked in this way and eaten with milk.  For growing children, it is one of the best of foods, containing, as it does, a large proportion of bone and muscle-forming material, while to almost all persons who have become accustomed to its use, it is extremely palatable.  The time required for its digestion is somewhat longer than that of wheaten meal prepared in the same manner.  It is apt to disagree with certain classes of dyspeptics, having a tendency to produce acidity, though it is serviceable as an article of diet in some forms of indigestion.  The manner of its preparation for the table has very much to do with its wholesomeness.  Indeed, many objectionable dishes are prepared from it.  One of these, called brose, much used in Scotland, is made by simply stirring oatmeal into some hot liquid, as beef broth, or the water in which a vegetable has been boiled.  The result is a coarse, pasty mass of almost raw oatmeal, an extremely indigestible compound, the use of which causes water brash.  A preparation called sowens, or flummery, made by macerating the husks of the oats in water from twenty-four to thirty-six hours, until the mixture ferments, then boiling down to the consistency of gruel, is a popular article of food among the Scotch and Welsh peasantry.  When boiled down still more, so it will form a firm jelly when cold, the preparation is called budrum.