The vegetable oils are of two distinct classes: the _drying_ or _setting_ represented by linseed, the _unctuous_ represented by rape-oil. They consist of two proximate elements, margarine and oleine; in all probability they will vary in their proportion of these, but in what degree I have not been able to ascertain. Though the agricultural chemists make no distinction, as far as I am aware, between these two classes of oils, the practitioners in medicine use them for distinct purposes. Cod-liver oil has been long used for pulmonary complaints; latterly, olive, almond, and rape oils are being employed as substitutes. These are all of the unctuous class of oils. Mr. Rhind, the intelligent medical practitioner of this village, called my attention to some experiments by Dr. Leared, published in the _Medical Times_, July 21st, 1855, with oleine alone, freed from margarine, which showed marked superiority in the effect; and I now learn from Mr. Rhind that he is at present using with success the pure oleine, prepared by Messrs. Price & Co., from cocoa-nut oil, one of the unctuous class. That linseed and others of the drying oils are used in medicine for a very different purpose, it seems unnecessary to state. The oleine of oil is known to be more easy of consumption and more available for respiration than margarine--a property to which its use in medicine may be attributable. If we examine the animal fats, tallow, suet, and other fat, they are almost wholly of the solid class, stearine or margarine, closely resembling or identical with the margarine in plants; whilst butter is composed of oleine and margarine, combining both the proximate elements found in vegetable oils. It seems worthy of remark that a cow can yield a far greater weight of butter than she can store up in solid fat; numerous instances occur where a cow gives off two pounds of butter per day, or fourteen pounds per week, whilst half that quantity will probably rarely be laid on in fat. If you allow a cow to gain sixteen pounds per week, and reckon seven for fat, there will only remain nine pounds for flesh, or, deducting the moisture, scarcely three pounds (2.97) per week, equal to .42, or less than half a pound per day, of dry fibrin.