DURING the last few years much unscrupulous ingenuity has been applied to the sophistication of butter. Both on the Continent and in this country the adulteration of this, the best of edible fats, has developed into quite an industry, having its own factories and its own chemists, and conducting its operations on a scale which, for a furtive, dishonest business, is really of remarkable magnitude. Considerable profits are alleged to be made, and it is therefore not surprising that the traffic has flourished in spite of all attempts at suppression. Perhaps it may be of interest to those readers of NATURE who are not chemists to have placed before them, with as little technicality as may be, a sketch of the modern methods of butter-adulteration, and of the means adopted or suggested to checkmate this form of fraud. The importance of the matter both to the consumer and the agriculturist may be pleaded as a justification for discussing the question at some little length.