The Romance of Modern Chemistry

THE ADULTERATION OF FOOD If a bulk of water were taken which weighed exactly 100 ounces, an equal bulk of pure new milk would weigh about 103 ounces, a little less or a little more, according to its source. That is, the average specific gravity of milk may be taken as 1 03. If, then, a certain sample of milk had a specific gravity of only 1 '02, we might be sure that it had been “ watered.” On the other hand, the fact that the specific gravity of a sample is 1'03, does not prove the milk to be satisfactory ; for, curiously enough, it is possible, by a judicious combination of watering and skimming, to get a product which has the same specific gravity as the original milk. The reader, of course, knows that the fat contained in the milk—in other words, the cream—rises slowly to the surface ; but he may not have drawn the conclusion that this fat must therefore be lighter than the milk. What is left after removing the cream—that is, the skimmed milk—is actually heavier, bulk for bulk, than the fresh milk ; its specific gravity is higher than 1 ’03. By adding water to this skimmed milk in the proper proportion, the specific gravity is brought down to the normal figure 1’03, and this “milk” is indistinguishable from fresh milk unless further tests are applied. It will probably be suggested that a mere glance at this “ milk ” would show that it had been skimmed and watered. But our adulterator is not so easily caught; he perpetrates fraud upon fraud, exhibiting an ingenuity which is worthy of a better cause. A judicious admixture of a yellow dye to skimmed and watered milk is found to produce a rich, creamy appearance, and the public is delighted with its milk supply. So is the adulterator; he has sold his “ milk ” at the standard price, and he has still the cream to dispose of. 263