course, it is unfit for infants and often for invalids. Milk is also sometimes adulterated by the addition of carbonate of soda, common salt, borax, or of coloring substances like arnotto (q.v.). Formaldehyde is the most dangerous of the adulterants used for the preservation of milk and other articles of food, and its use should he strictly forbidden by law. Chalk, calves' brains, and similar adulterants are not known to be used anywhere at present, and have perhaps never been used at all. The methods of detecting adulteration which are noted above are rapid and sufficient for ordinary purposes of controlling the supply of milk. When, however, it is required to determine precisely the nature and extent of adulteration, quantitative chemical analysis alone can furnish the desired information. The most important steps in the analysis are the determination of total solids and the determination of fat. To determine the total solids, the chemist weighs out 10 grams of the milk in a platinum dish, adds 30 grams of freshly ignited sand, evaporates on a water-bath, and dries the residue in an oven kept at about 105° C. (221° F.). On cooling, he weighs the dry residue and thus finds how much water, and hence how much solids, was contained in the 10 grams of milk employed. To determine the fats, a known quantity of milk is treated with ordinary ether, which is an excellent solvent for fats; on evaporating the ethereal solution, the fats remain behind and may lie weighed directly. A qualitative examination for nitrates is useful, because pure milk contains none of these salts, while natural waters, especially if bad, contain them in considerable quantities, and thus the adulteration of milk with natural waters may often be readily detected. The skimming of milk has often been masked by the addition of foreign animal fats, the detection of which may be a matter of considerable difficulty. The nutritive value of some such fats is much inferior to that of the natural fat of milk, and hence this form of fraud is no less damnable than the other forms referred to above.
Butter is adulterated by the mechanical admixture of a variety of substances, including water, buttermilk, foreign animal and vegetable fats, cheese, flour, chalk, common salt, gypsum, alum, glucose, borax, boracic and salicylic acids, coloring matters like aniline yellow, butter yellow, and certain natural dyes. The amount of water in unadulterated butter does not exceed 12%; the amount of salt in salt butter should not exceed 5%. Adulteration in butter cannot usually be detected except by chemical analysis, the principal step of which is the determination of fats by extraction with ordinary ether. Oleo-margarine is not a bad product, but should be truthfully labeled when brought to the market. See also Butter; Butter-Color; and Butter-Making.
Cheese (Swiss cheese) is often found adulterated with foreign fats, potato flour, and certain coloring substances. The fraud can be detected by a chemical examination. See Cheese.
Bread is often adulterated, for the purpose of improving its color, with alum or with sulphate of copper. The presence of these substances may be detected by digesting a sample of the bread with water, and leaving a strip of pure gelatin in contact with this for several hours. On dissolving the gelatin in wood alcohol containing logwood and ammonium carbonate, the presence of alum is shown by the appearance of a blue coloration. The presence of copper sulphate is similarly revealed by the logwood solution turning green. The addition of alum may mask the unwholesome qualities of poor bread, and may thus be a source of considerable danger. On the other hand, its normal presence in baking-powders is considered by some authorities as entirely free from objection because, according to them, the alum is during the baking process converted into an insoluble, and hence harmless, aluminum phosphate.
Flour is often adulterated by the addition of cheaper cereals, and the presence of these may be detected microscopically. The addition of gypsum and other mineral matter is practiced much more extensively in the European countries than in the United States. The presence of such adulterants may be revealed by determining the amount of ash left on burning a known quantity of flour.
Confectionery has been adulterated with a variety of coloring substances, poisonous as well as harmless; with starch, sawdust, artificial "fruit oils," crude benzaldehyde, and a variety of other substances. Within recent years, however, the adulteration of confectionery has greatly diminished.
Coffee, when sold in the ground state, is often adulterated with considerable amounts of chicory, roasted beans or peas, tanbark, sawdust, stove-rust, etc. The presence of adulterants may be detected by chemical analysis, the principal steps of which consist in the determination of the percentage of matter soluble in water, and the determination of sugars before and after treatment with hot mineral acids. The latter cause a considerable increase of sugar in pure coffee, while they have no effect on the amount of sugar contained in chicory.
Tea is often adulterated with the leaves of linden, sage, strawberry, and other plants. The presence of these may be detected microscopically, or else by determining chemically the amount of caffeine, which is hardly ever less than 1% in pure tea. "Spent tea" is often sold, and to make the infusion appear stronger than it really is, iron salts are added to the leaves. See Tea.
Cocoa and chocolate are often found to contain flour, potato meal, sawdust, mutton tallow, vegetable oils, and a variety of other substances. The presence of adulterants is detected by determining the amounts of theobromine, fat, dextrin, starch, and inorganic matter.
Sugar, that is, ordinary white cane sugar, is usually very pure. Glucose, terra alba, sand, and certain other substances are sometimes, though rarely, used as adulterants. On the other hand, brown sugars often contain considerable amounts of glucose and other adulterants. Pure cane sugar has a dry, white appearance and a pure, sweet taste: when burned it leaves very little ash. It has been held that the presence of 4% of sand in Manila sugar is almost unavoidable. If, however, it is possible to prove that the percentage of sand has been intentionally raised by the seller to that amount, the latter is punishable criminally under modern statutes.
Honey is often largely adulterated with syrup, meal, corn-starch, cane sugar, grape sugar, etc. The fraud can only be detected by chemical analysis.
