Milk.—Frauds consist generally in adding water or removing fat (skimming). As the milk of healthy cows varies in composition within certain limits, it is necessary to have a standard of purity, which has been fixed upon in New York as follows: Nearly 1,000 cows have been examined, with reference to the specific gravity of their milk, in New York, New Jersey, and Connecticut. The maximum specific gravity was 1.039 in milk of an Alderney cow. The minimum for normal milk from a healthy cow was 1.029. The specific gravity is determined by an instrument called a lactometer, on which 0 stands for 1,000, the specific gravity of water, and 100 for 1,029, that of the poorest milk from a healthy cow. The composition of such milk, adopted by the English Society of Public Analysts and the New York City Board of Health, as a result of fifty analyses, is as follows:
| Fat | 2.5 |
| Solids, not fat (sugar, salt, etc.) | 9.0 |
| Water | 88.5 |
| 100.0 |
Method of using the Lactometer.—Put the milk in a vessel so deep that the lactometer, when introduced and allowed to float, shall not touch the bottom. Notice the reading of the scale at the surface of the milk. If it is less than 100, it gives the percentage of milk in the sample. For example, if the reading be 80, the sample contains 80 per cent of milk and 20 per cent of water.
Sources of Error.—Milk very rich in cream may possibly, though not probably, register less than 100, but its very appearance will show that it has not been thinned by water or by skimming.
Skimmed milk, especially if a little salt has been added, may register high above 100, but its thinness and blueness will show that it has been doctored.
Condensed milk was carefully analyzed, and found to be unobjectionable. (C. E. Munsell, Ph. D.)
Olive-Oil.—Often adulterated with poppy, cotton-seed, ground or peanut, sesame, rape-seed, colza or beechnut oil, all harmless. Sixteen samples; nine adulterated. (Caldwell.)
Pickles.—Nine samples. None contained copper or any other metal. The only sample that possessed a suspiciously green appearance was found to contain alum. (Lattimore.)
Rum.—Twenty-five samples. No objectionable additions found. (Engelhardt.)
Sirups.—Three samples of maple-sirup. Two were pure, and one, manufactured in Chicago and sold in cans, contained 35 per cent of artificial glucose. In 1870 Dr. Chandler found .02 per cent of tin in each of two samples of sugar-house sirups. This represents .8 grain of tin to the gallon. A common adulterant of sirups is glucose, which diminishes their sweetening power, but is not considered injurious.