It yields by distillation an oil termed "oil of spike," or, to distinguish it from oil of L. stæchas, "true oil of spike." It is darker in color than the oil of L. vera, and much less grateful in odor, reminding one of turpentine and rancid coker nut oil. It is used by painters on porcelain, and in the manufacture of varnishes. It is often largely admixed with essence of turpentine.
L. Stæchas (Stichas) was discovered prior to the year 50 A.D. in the Stæchades Islands (now the Islands of Hyères), hence the name. At present it is found wild in the South of Europe and North of Africa, also at Teneriffe. The leaves are oblong linear, about half an inch long (sometimes an inch long when cultivated), with revolute edges and clothed with hoary tomentum on both surfaces; the spike is tetragonal, compact, with a tuft of purple leaves at the top; the calyces are ovate and slightly shorter than the tube of the corolla. The whole plant has a strong aromatic and agreeable flavor. There is a variety of this species (L. macrostàchya) native of Corsica, Sicily, and Naples, which has broader leaves and thicker octagonal spikes.
L. stæchas is known in Spain as "Romero Santo" (sacred rosemary). Its essential oil (also that of L. dentata) is there obtained for household use by suspending the fresh flowering stalks, flowers downward, in closed bottles and exposing them for some time in the sun's rays; a mixture of water and essential oil collects at the bottom, which is used as a hæmostatic and for cleansing wounds.
The specific gravity of Spanish oil of L. stæchas is 0.942 at 15° C. It boils between 180° and 245°. The odor of this oil is not at all suggestive of that of lavender, but resembles more that of oil of rosemary, possessing also the camphoraceous odor of that oil. In India this oil is much prized as an expectorant and antispasmodic.
LAVANDULA VERA. LAVANDULA SPICA.
(From photographs of the plants. Natural size.)
The other species which are distinctly characterized are L. pedunculata, L. viridis, L. dentata, L. heterophylla, L. pyrenaica, L. pinnata, L. coronopifolia, L. abrotonoides, L. Lawii, and L. multifida.
The L. multifida is synonymous with L. Burmanii. In Spain the therapeutic properties of L. dentata are alleged to be even more marked than in the oils of any of the other species of lavender. It is said to promote the healing of sluggish wounds, and when used in the form of inhalation to have given good results in cases of severe catarrh, and even in cases of diphtheria. In odor this oil strongly suggests rosemary and camphor. Its specific gravity is 0.926 at 15° C. It distills almost completely between 170° and 200°.
The specific gravity of the oil of L. vera (according to Flückiger and Hanbury, Pharmacographia) ranges between 0.87 and 0.94. The same authorities state that in a tube of 50 millimeters the plane of polarization is diverted 4.2° to the left.
Dr. Gladstone found (Jnl. Ch. Soc., xviii., 3) that a sample of pure oil of L. vera, obtained from Dr. S. Piesse, indicated a specific gravity of 0.8903 at 15° C., and that its power of rotating the plane of polarization (observed with a tube ten inches long) was -20°. Compared with these results he found the sp. gr. of oil of turpentine to be 0.8727, and the rotatory power -79°.