| | | clear | " | " | 1 : 500 " |cherry-red | " | | | and opaque | " | " | 1 : 100 " |dark cherry-red | " | | | and opaque | Cassia |brownish-yellow| 1 : 1000 " |brownish-red to | black. | | | hyacinth-red | " | " | 1 : 100 " |dark brown-red | " Sassafras |yellowish | 1 : 1000 " |yellowish-brown | " Star anise |pale yellow | 1 : 1000 " |dark wine-yellow | " Valerian |pale greenish | 1 : 100 " |brownish-yellow | " Rue |slightly | 1 : 100 " |brown-yellow | ash-gray. | yellowish | | | Bergamotte |yellowish | 1 : 1000 " |dark yellow | " " | " | 1 : 100 " |brownish-red | " -------------+---------------+---------------+------------------+------------- If these oxygenated oils are mixed with oils free from oxygen, for instance, oil of turpentine, they show exactly the same behavior as oils free from oxygen; the nitroprusside of copper is not decomposed and retains its gray-green color. If, for instance, oil of cloves is mixed with oil of turpentine, the red coloration by nitroprusside of copper does not appear. III. _Hager's alcohol and sulphuric acid test._--Bring into a test-tube of about 0.5 inch diameter, five to six drops of the oil to be tested and twenty-five to thirty drops of pure concentrated sulphuric acid, and mix the two fluids by shaking, whereby either no heating takes place or a scarcely perceptible one, or the heating is strong or very vigorous and in some cases increased to the evolution of vapors. The mixture is either clear or turbid. After complete cooling, add to the mixture eight to ten cubic centimeters of 90 per cent. alcohol, and after closing the tube with the finger, shake vigorously. The mixture now shows a different color, is clear or turbid, and the deposit formed after standing for one day is also differently colored and either soluble or insoluble in boiling alcohol. The mixture of oil, sulphuric acid and alcohol is perfectly clear and transparent with oils of bitter almonds, fennel, clove and rose; with anise-seed oil and star anise-seed oil only the alcoholic layer over the mixture of sulphuric acid and oil is clear. The mixture of oil, acid and alcohol is slightly turbid or nearly clear with oils of valerian, peppermint and field thyme. With most of the other volatile oils occurring in commerce, the mixture is more or less milky turbid. Heating of the oil and acid mixtures does not take place with pyrogenous oils (petroleum, benzine) or only to a very slight degree, as with oils of peppermint and mustard.