The method of testing for dilution is by the lactometer to determine specific gravity, which is lowered by admixture of water; in exact reverse, it detects skimming (which in creases specific gravity by removing the lighter cream) by showing normal specific gravity when looks and taste are inferior. Skimming is also inferred from increase in transparency, as indicated by the lactoscope; opaque normal milk needs thinning with a certain percentage of water before a dark object or black line drawn on a white surface will show through; the less water a given sample needs for this visibility, the less cream it contains. For more precise determination the chemist finds the amount of solids in a sample by evaporating a mixture of milk and newly-heated asbestos and weighing the the amount of fats, by dissolving them out with ether from a measured strip of blotting paper and evaporating. Wa tering may often be detected by testing for nitrates, which milk does not contain and most water does, and contaminated water practically always. The detection of animal fats used to replace cream is not easy, though the butyrates have some individual qualities.
This is perhaps the most heavily and universally adulterated article in the mar ket; only a small percentage of it is pure. For one harmless adulteration the public is responsible, as for butter-color and pickle green ; that of turmeric or coal-tar color to give it the bright yellow demanded by cus tomers, while real mustard is very dull. But it is usually diluted with starch,— wheat, corn or rice,— millet, rape-seed, flaxseed, old tur nip- or radish-seed, charlock (wild mustard) seed, cayenne pepper, corn-meal, gypsum and wheat-bran. The adulteration is so large in some samples of mustard-paste that salicylic acid is added to keep it from spoiling. For starch, easy tests are iodine, which turns it blue, and its thickening in boiling water; for mineral matter the chemist determines the amount of ash. For the others, though the microscope is useful, the best remedy is to pay for a known brand,— which indeed is best of all.
Olive A large part of the so-called olive oil of the market is cottonseed, peanut or mustard oil or greatly mixed with it; prob ably the equal in quality and taste of the genu ine (as it is indistinguishable), but a fraud in price through deception. The very finest qual ity of olive oil is rarely adulterated as the taste is easily impaired by even a slight admix ture. Tests: Nitric acid turns olive oil from pale green to dark green within a few minutes. Should the color change to orange or brownish, some other oil is present.
Pickles and Canned The public demand for bright green pickles has been gratified by boiling them in copper kettles with vinegar and some alum, the vinegar forming the highly poisonous acetate of copper with the kettle and coloring the pickles green by forming albuminate or leguminate of copper on the surface of the pickles. As only a minute proportion of the copper salt remains in the liquid the determination of its presence is a task for the analytical chemist. The same process is said to be gone through with peas; and even the copper salts directly added, which would be a basis for a criminal prosecution. The presence of metallic salts from the can results from the action of certain vegetable substances on the tin coating and upon the iron after the tin is dissolved. These sub stances are not 'necessarily acids, as canned pumpkin will show a much larger percentage of tin salts than does canned plums. These salts of tin have not been proved deleterious, and, besides, oxide of tin would make the canned food too nauseous to eat long before it reached even a medicinal proportion, and oxide of lead has not been found in any quan tity. By far the greatest danger in canned foods is that due to carelessness in the canning process, resulting in the development of putre factive ptomaines which have been the cause of many deaths.
Preserves, Jams, Gelatine and glue are often used to help the fruit to jelly (not always an easy thing to assure even by experts) and are often not restricted to the amount needed; the goods are also artificially colored and flavored with so-called oils, chemical analysis being needed to determine the constituents. The demand for cheap jams and jellies brings into the market concoctions of glucose and apple juice artificially flavored and colored to conform to the name on the labed on the jar. In some instances a little real fruit is scattered through the material. The deception is self-evident, as every housewife knows the impossibility of making such goods at the price. Zinc oxide has been found in preserves, from its use as cement to make cov ers of jars airtight. Most of the cheap prod ucts contain the allowable percentage of ben zoate of soda to prevent their decay. To make up for the lack of sweetness in the glucose saccharine is a frequent addition. The apple pulp from cider-mills is a' common basis of cheap jams and this is sometimes given body by the addition of boiled starch, agar-agar or dextrine. If in good condition none of these adulterations is injurious to health. The fraud is in the name under which they are sold.