It is evident from this that it would not pay to add such a quantity in such a manner as a mere adulterant. The baker uses it for improving the bread, from his point of view. The _stuff_ or _rocky_ consists, according to Tomlinson, of one part of alum to three parts of common salt. The same authority tells us that the bakers buy this at 2_d._ per packet, containing 1 lb. in each, and that they believe it to be ground alum. They buy it thus for immediate use, being subject to a heavy fine if they keep alum on the premises. The quantity of the mixture ordinarily used is 8 oz. to each sack of flour weighing 280 lbs., so that the proportion of alum is but 2 oz. to 280 lbs. As one sack of flour is (with water) made into eighty loaves weighing 4 lbs. each, the quantity of alum in 1 lb. of bread amounts to 1/160th of an oz. The _rationale_ of the action of this small quantity of alum is still a chemical puzzle. That it has an appreciable effect in improving the _appearance_ of the bread is unquestionable, and it may actually improve the quality of bread made from inferior flour. One of the baker’s technical tests of quality is the manner in which the loaves of a batch separate from each other. That they should break evenly and present a somewhat silky rather than a lumpy fracture, is a matter of trade estimation. When the fracture is rough and lumpy, one loaf pulling away some of the just belongings of its neighbour, the feelings of the orthodox baker are much wounded. The alum is said to prevent this impropriety, while an excess of salt aggravates it. It appears to be a fact that this small quantity of alum whitens the bread. In this, as in so many other cases of adulteration, there are two guilty parties—the buyer who demands impossible or unnatural appearances, and the manufacturer or vendor who supplies the foolish demand. The judging of bread by its whiteness is a mistake which has led to much mischief, against which the recent agitation for ‘whole meal’ is, I think, an extreme reaction. If the husk, which is demanded by the whole-meal agitators, were as digestible as the inner flour, they would unquestionably be right, but it is easy to show that it is not, and that in some cases the passage of the undigested particles may produce mischievous irritation in the intestinal canal. My own opinion on this subject (it still remains in the region of opinion rather than of science) is that a middle course is the right one, viz. that bread should be made of moderately-dressed or ‘seconds’ flour rather than over-dressed ‘firsts’ or undressed ‘thirds’—_i.e._ unsifted whole-meal flour.