1483. To Test the Purity of Oil of Neroli

1483.    To Test the Purity of Oil of Neroli. This is the oil of orange flowers, and is commonly adulterated with alcohol, or with the oil of orange leaf (essence de petit-grain), and generally with both. The presence of the first is easily determined (see No. 1476 (To Detect the Presence of Alcohol in Essential Oils)); that of the second only by comparing the odor of a drop of the suspected oil, placed on a piece of paper, with a drop of pure neroli similarly treated.

1484. To Test the Purity of Otto of Roses

1484.    To Test the Purity of Otto of Roses. Cooley says : " The common adulterants are the oils of rhodium, sandal wood, and geranium, with camphor, and occasionally with spermaceti, to give the spurious article the usual crystalline appearance. Pure otto has a bland, sweet taste; if it be bitter, it contains oil of rhodium or sandal wood; if it bo pungent or bite the palate, it contains either oil of geranium or camphor, and most probably both; if it imparts an unctuous sensation to the palate, or if it leaves a greasy stain on paper, it contains spermaceti. A single drop of pure otto of roses exposed for some hours under a bell-glass, in the cold, to the vapor of a few grains of iodine, remains white, and continues so on subsequent exposure to the air. A sample adulterated with foreign oil, on the contrary, becomes yellow or yellowish-brown, and continues subsequently to darken, until it becomes of a deep brown color, or even perfectly black, according to the extent of the adulteration. A single drop of pure otto placed on a watch glass with one drop of concentrated sulphuric acid (oil of vitriol), and stirred with a glass rod, retains the purity of its color and odor; but a sample adulterated with other oil becomes more or less brown, and evolves peculiar odors - that from oil of geranium being strong and disagreeable; that from oil of rhodium being increased and rendered unctuous and cubeb-like; that from camphor, characteristic and combined with acidity; that from spermaceti, unctuous and clearly perceptible." Dr. E. Baur, of Constantinople, has had the opportunity of preparing a standard otto of rose on the spot, and was also in a position such as scarcely any other chemist ever was for investigating the whole subject. He says that pure otto gives, with iodine and with iodide of potassium and starch, the same reactions as when it is mixed with geranium oil, and even those with pure geranium oil are hardly different. He further says that many attempts have been made to discover some chemical reaction which would reveal the falsification of otto with geranium oil, but hitherto mostly in vain.

1485. To Test the Purity of Oil of Cloves

1485.    To Test the Purity of Oil of Cloves. Oil of cloves is frequently adulterated with inferior essential oils, but when pure it exhibits the following results: When shaken with pure liquor of ammonia, it coagulates, and crystallizes after fusion by a gentle heat: Treated with an alcoholic solution of potassa, it congeals into a crystalline mass, with total loss of its odor: A solution of chromate of potassa converts it into brown flakes, whilst the salt loses its yellow color.