_Apropos_ of the practice of cheating by means of the adulteration of foods and drinks, it may not be out of place here to mention that during the discussion a member in whom Mr. Bright expressed great confidence, announced that the use of alum in bread, so far from being injurious, was _positively beneficial_. Doctor Letheby, however, is of a somewhat different opinion. Recently, at the Society of Arts, he read a paper on the subject. Here are his opinions on the matter: “By the addition of alum, inferior and even damaged flour may be made into a tolerable looking loaf. It is the property of alum to make the gluten tough, and to prevent its discoloration by heat, as well as to check the action of the yeast or ferment upon it. When, therefore, it is added to good flour, it enables it to hold more water, and so to yield a larger number of loaves; while the addition of it to bad flour prevents the softening and disintegrating effect of the yeast on the poor and inferior gluten, and so enables it to bear the action of heat in the progress of baking. According to the quality of flour, will be the proportion of alum, and hence the amount will range from 2 ozs. to 8 ozs. per sack of flour. These proportions will yield from 9 to 37 grains of alum in the quartern loaf, quantities which are easily detected by chemical means. Indeed, there is a simple test by which much smaller quantities of it may be readily discovered. You have only to dip a slice of the bread into a weak solution of logwood in water, and if alum be present, the bread will speedily acquire a red or purplish tint. Good bread should not exhibit any black specks upon its upper crust; it should not become sodden and wet at the lower part by standing; it should not become mouldy by keeping in a moderately dry place; it should be sweet and agreeable to the taste and smell; it should not give, when steeped, a ropy, acid liquor; and a slice of it taken from the centre of the loaf should not lose more than forty-five per cent. by drying.” Again, speaking of the cruelty and dishonesty of the various “sophistications” practised by the vendors of food as regards the inefficacy of the laws made for its suppression, the good doctor says: