DELETERIOUS ADULTERATIONS OF FLOUR.—­Besides the fraud frequently practiced of compounding whole-wheat flour from inferior mill products, white flour is sometimes adulterated—­more commonly, however, in European countries that in this—­with such substances as alum, ground rice, plaster of Paris, and whiting.  Alum is doubtless the most commonly used of all these substances, for the reason that it gives the bread a whiter color and causes the flour to absorb and retain a larger amount of water than it would otherwise hold.  This enables the user to make, from an inferior brand of flour, bread which resembles that made from a better quality.  Such adulteration is exceedingly injurious, as are other mineral substances used for a similar purpose.

The presence of alum in flour or bread may be detected in the following way:  Macerate a half slice of bread in three or four tablespoonfuls of water; strain off the water, and add to it twenty drops of a strong solution of logwood, made either from the fresh chips or the extract.  Then add a large teaspoonful of a strong solution of carbonate of ammonium.  If alum is present, the mixture will change from pink to lavender blue.

The Journal of Trade gives the following simple mode of testing for this adulterant:  “Persons can test the bread they buy for themselves, by taking a piece of it and soaking it in water.  Take this water and mix it with an equal part of fresh milk, and if the bread contains alum, the mixture will coagulate.  If a better test is required, boil the mixture, and it will form perfect clot.”

Whiting can be detected by dipping the ends of the thumb and forefinger in sweet oil and rubbing the flour between them.  If whiting is present, the flour will become sticky like putty, and remain white; whereas pure flour, when so rubbed, becomes darker in color, but not sticky.  Plaster of Paris, chalk, and other alkaline adulterants may be detected by a few drops of lemon juice:  if either be present, effervescence will take place.

CHEMISTRY OF BREAD-MAKING.—­Good flour alone will not insure good bread.  As much depends upon its preparation as upon the selection of material; for the very best of flour may be transformed into the poorest of bread through improper or careless preparation.  Good bread cannot be produced at random.  It is not the fruit of any luck or chance, but the practical result of certain fixed laws and principles to which all may conform.

The first step in the conversion of flour into bread is to incorporate with it a given amount of fluid, by which each atom of flour is surrounded with a thin film of moisture, in order to hydrate the starch, to dissolve the sugar and albumen, and to develop the adhesiveness of the gluten, thus binding the whole into one coherent mass termed dough, a word from a verb meaning to wet or moisten.  If nothing more be done, and this simple form of dough be baked, the starch granules will be ruptured by the heat and