oils are easily detected by a permanent greasy stain upon paper, and by a non-volatile residue when the suspected oil is subjected to distillation. Alcohol may be tested for in several ways. If the oil be shaken in a graduated tube with an equal volume of water or glycerin, and then allowed to stand at rest, any diminution in the volume of the oil would indicate alcohol, and approximately also the proportion present; if considerable alcohol be present, the characteristic lambent blue flame of burning alcohol will be observed if a portion of the suspected oil is ignited in a dark room; fused

calcium chloride and dry potassium acetate are insoluble in volatile oils, but in the presence of alcohol become soft and even liquid, depending upon the proportion of alcohol; potassium acetate and sulphuric acid added to volatile oils will generate acetic ether if alcohol be present, which may be detected by its odor; and anilinered is insoluble in pure volatile oils, but colors these red in the presence of alcohol. Adulterations with rectified petroleum are often not easily detected, and may require a careful chemical exami

nation; for it, as well as for the inferior volatile oils, the Pharmacopoeia prescribes appropriate tests under the head of the respective oils likely to be thus contaminated.

The usual method of obtaining volatile oils is by distillation. In some of the Asiatic countries, where the world's supply of a few volatile oils is still obtained, rather crude methods prevail even at the present time. Thus the plan is followed of using wooden cylindrical stills provided with a perforated diaphragm or false bottom, as shown in Fig. 204, on which the oil-yielding material is placed, water being put into the boiler on which the still rests and direct

Distillation of oil of cajuput in the Molucca Islands.

heat applied until the water boils, and the boiling continued as long as the distillate shows the presence of volatile oil. As shown in the illustration, the vapors are condensed in the cup-shaped condenser above the still, and flow from there into a suitable receiver, made of wood and lined with tin, whence the watery portion of the distillate flows back into the still, while the oil rises to the surface and is removed when a sufficient quantity has collected. In Fig. 205 may be seen the peculiar arrangement of a wooden still with tin condenser for the distillation of oil of cassia cinnamon. The still, as in the preceding case, is provided with a perforated bottom and rests upon an iron boiler placed directly over the firepot of a brick furnace. The distillate collects in a gutter near the bottom of the cylindrical condenser and flows from there into earthenware receivers. Oil of cinnamon being heavier than water, the distillate is collected in a series

distillation. A still cruder apparatus, in use as recently as 1894, is shown in Fig. 206. It is used for the distillation of oil of cajuput,

FIG. 207.

of vessels in which the oil sinks to the bottom and the aqueous portion flows into another vessel, to be again used in a subsequent

and consists of a wooden cask, a, into which are placed the leaves of the melaleuca plant and some water, and which is heated by means of a rudely constructed fireplace. The vapors are carried through the tin still-head 6 by means of a tube into the second cask e, which is kept supplied with cold water running in through the tube d, made of bamboo, where they are condensed and flow through a funnel-shaped device, made of cocoanut shell, into a bottle. The oil and water gradually separate, the oil rising to the surface and the water flowing into the tub e through a small hole near the bottom of the bottle.

Although the boiling-points of volatile oils are considerably above that of water, the oils pass over rapidly with the vapor of boiling water, and in the leading establishments in this country and Europe volatile oils are now distilled by passing steam under pressure into stills which contain the material on a series of perforated trays

extending across the inner body of the still; by this method compaction is avoided, the steam can readily penetrate every particle of the material, and a much finer quality of oil results, since prolonged contact with boiling water has a deleterious effect upon many oils. Fig. 207 represents the interior of a modern establishment for the distillation of volatile oils by steam, as carried on by Messrs. Schimmel & Co., at Leipzig, Germany, to whom the author is indebted for the loan of this and other illustrations shown in this chapter. Whenever the volatile oil is deeply imbedded in the material, as in the case of cloves, cubebs, and many barks and seeds, it is necessary that this first be reduced to a coarse powder so as to facilitate the liberation of the oil. The distillate, which is a mixture of oil and water, is collected in suitable receivers, either in the form of Florentine flasks with a single outlet tube near the bottom

short one near the top; as the distillate cools, it separates into two distinct layers, one consisting of pure oil and the other of water holding some oil in solution and suspension, which is subsequently

and reaching nearly to the top, as shown in Fig. 208, or of tall cylinders provided with two tubes, a long one near the bottom and a