Acid Mercuric Nitrate.—1 part by weight of Hg, 2 parts HNO3 (sp. gr. 1.42). Dilute 25 times with water.
Experiment No. 19
Testing for Oleomargarine
Apply the following tests to two samples of the material:
Boiling or Spoon Test.—Melt the sample to be tested—a piece about the size of a chestnut—in a large spoon, hastening the process by stirring with a splinter. Then, increasing the heat, bring to as brisk a boil as possible and stir thoroughly, not neglecting the outer edges. Oleomargarine and renovated butter boil noisily, sputtering like a mixture of grease and water, and produce no foam, or but very little. Genuine butter boils with less noise and produces an abundance of foam.
Waterhouse Test.—Into a small beaker pour 50 cc. of sweet milk. Heat nearly to boiling and add from 5 to 10 gms. of butter or oleomargarine. Stir with a glass rod until fat is melted. Then place the beaker in cold water and stir the milk until the temperature falls sufficiently for the fat to congeal. At this point the fat, if oleomargarine, can easily be collected into one lump by means of the rod; while if butter, it will granulate and cannot be collected.
(From Farmers' Bul. 131, U. S. Dept. of Agriculture.)
1. Name two simple tests for distinguishing butter and oleomargarine. 2. Describe these tests. 3. Why do butter and oleomargarine respond differently to these tests? 4. Are these tests based upon chemical or physical properties of the fats?