OIL-BEARING PLANTS 



OIL-BEARING PLANTS 



495 



Place of production in the plant. 



Not only are volatile oils produced by many 

 widely separated members of the vegetable king- 

 dom, but they are contained in the most various 

 parts of the plant. (1) In many cases they are de- 

 veloped in hair-like structures which grow on the 

 leaves and stems of plants, chiefly herbaceous, and 

 give to the herbage of these plants the odor charac- 

 teristic of them. Peppermint, spearmint, penny- 

 royal, sage, catnip, lavender and marjoram belong 

 to this class. (2) In many cases the oils are formed 

 in internal glands or secreting structures and there 

 developed and retained. Such accumulation is seen 

 in the fruits (sometimes called seeds) of the Umbel- 

 lifercB, e. g., anise, caraway, coriander, fennel ; in 

 the fruit, rind and the foliage of the orange and 

 lemon trees ; in the leaves, bark and wood of the 

 sassafras ; in the needles, bark and wood of many 

 of the cone-bearing trees, as the fir balsam, long- 

 leaved pine, white cedar and juniper. (3) In still 

 other cases, the volatile product does not exist in 

 the plant, but is formed by chemical changes fol- 

 lowing preparatory treatment of the parts involved. 

 In the case of those products in which the develop- 

 ment of prussic acid is a characteristic result, the 

 leaves or fruits yielding it must be crushed and 

 thoroughly moistened so as to bring together those 

 substances which by their action on each other 

 cause the development of this acid. Usually a sub- 

 stance belonging to the group of bodies known as 

 enzymes acts on a substance belonging to the 

 group of bodies known as glucosides. When water 

 is present, this reaction results in the formation 

 of prussic acid and also of other less important 

 substances. 



This condition of things is encountered in obtain- 

 ing the so-called oil of bitter almonds, whose chief 

 sources are the kernels of almonds and apricots. 

 Peach kernels contain similar substances and yield 

 this oil also. The same general condition exists also 

 in the green leaves and the bark of the black 

 cherry, which yields this poisonous principle only 

 after such a chemical change takes place. Similar 

 in its general features is the situation in mustard 

 seeds and horseradish, which owe their pungency 

 to a volatile oil that is produced by a chemical 

 change taking place between substances present in 

 the seeds and root respectively. The volatile oil 

 of wintergreen illustrates a similar method of 

 formation. 



Thus it is clear that for the production of vola- 

 tile oils many different parts of plants are used, 

 and also that these are treated in very different 

 ways. 



Method of obtaining volatile oils. 



The process of obtaining volatile oils consists 

 especially in exposing the oil-containing herbage, 

 seed, wood, or bark to the action of a current of 

 live steam which is then condensed, yielding water 

 and the oil. The most important parts of a dis- 

 tilling apparatus are the following : (1) The boiler 

 which yields the live steam; (2) the distilling 

 chamber in which the substance to be distilled is 

 packed and exposed to the live steam, which is 



usually admitted at the bottom ; (3) the condenser 

 in which the pipes carrying the live steam laden 

 with the vapors of the volatile oil are brought 

 from an outlet near the top of the distilling cham- 

 ber into an artificially cooled series of tubes from 

 which the condensed steam and oil fiow out into 

 some proper receptacle. The oil, usually somewhat 

 impure, floats generally as a superficial layer on 

 the water, from whence it is skimmed or otherwise 

 drawn off for storage or purification. [Fig. 1391, 

 Cyclopedia of American Horticulture, shows a 

 mint still in section; and there is a discussion 

 of peppermints and spearmint, and a botanical 

 account of the cultivated species of Mentha.] 



Volatile oil production in the United States. 



At the present time the growing and distillation 

 of volatile oil-producing plants are practiced to a 

 limited extent in several parts of the country. The 

 most conspicuous example is peppermint, which is 

 grown in southern and central Michigan, northern 

 Indiana and in Wayne county, New York. Michigan 

 is at present probably the most important pepper- 

 mint oil region of the world. Japan produces a 

 large quantity of an oil called commercially pepper- 

 mint oil. England and Germany are smaller pro- 

 ducers. Wormwood oil, formerly grown chiefly in 

 Prance and other parts of Europe, is now grown 

 largely in Michigan, Wisconsin and Nebraska, the 

 United States furnishing a very considerable part 

 of the world's product. Spearmint oil is also pro- 

 duced in small quantity. Spearmint supplies mate- 

 rial for mint julep. 



Among the volatile oils produced in the United 

 States, some are obtained from wild plants which 

 are collected in the fields and forests for distilla- 

 tion. Sassafras oil is distilled at scattered points 

 in Pennsylvania, Virginia and other parts of the 

 country occupied by the sassafras tree, even as far 

 west as Missouri. Wintergreen oil is distilled in 

 small quantities in Michigan, Connecticut and other 

 regions where the wintergreen plant and the sweet 

 birch (which yields the oil on distillation of the 

 bark) are found abundantly. Perhaps the most im- 

 portant single volatile oil is distilled from the 

 resinous substances which exude from the wounded 

 trunks of the turpentine-yielding pines. The resi- 

 nous exudate on distillation yields the oil of tur- 

 pentine of commerce. On the Pacific coast there is 

 a sparing distillation of the leaves of the eucalyptus 

 trees grown so frequently in that region. The ker- 

 nels of California bitter almonds, and to a much 

 larger extent the kernels of apricots, are also a 

 commercial source of the so-called oil of bitter 

 almonds. 



Volatile oil importation. 



In addition to the above home production, this 

 country imports volatile oils and products derived 

 from them to no small extent. In the following 

 tables, the report of the National Customs author- 

 ities for the year ended June 30, 1905, gives the 

 sorts, values, and quantities of some of the most 

 important kinds of products imported during the 

 period indicated; 



