The first investigation suggested by the new theories that was of positive value, was the elementary analysis of turpentine oil made by Houtton-Labilliardiere.1) He found the ratio of carbon to hydrogen to be five to eight, the same that was later established for all hemiterpenes, terpenes, sesquiterpenes and poly-terpenes.

1) Crell's Chem. Annalen. 1788, II. 219 and 488.

2) Journ. de Chim. et de Phys. 2 (1794) 178. - Crell's Chem. Annalen. 1795, II. 195, 310 and 430.

3) A. E. von Nordenskiold, Scheele's nachgelassene Briefe und Auf-zeichnungen. Stockholm 1892. pp. XXI, 86, 408, 458 and 466. - Pharm. Rundschau (New York) 11 (1893), 28 and 48.

4) Journ. de Chim. et de Phys. 1794, II. 178. - Crell's Chem. Annalen. 1795, II. 195, 310 and 430.

Attention has already been called to the crystalline deposits that had been observed in the course of several centuries. These were mostly considered as identical with ordinary camphor because like it they were volatile, soluble in alcohol and fatty oils, and burned with a smoky flame. Only in a few instances, however, had these deposits been proven to be identical with camphor. Berzelius,2) therefore, argued against the indiscriminate generic use of the term camphor.

"Several writers have applied the term camphor to all solid volatile oils. Thus a well known term of a commonly used substance has been given a different meaning from the one of long standing. Because of this disadvantage I felt myself constrained to disregard entirely this use of the word camphor."

In its place he suggested the use of the term stearoptene (fromDistilled Oils Known And In Use 24 tallow, andvolatile). He pointed out the analogy existing between volatile and fatty oils in so far as they can be a mixture of several oils having different congealing points. Thus oils may, under favorable circumstances, be separated into an oil which is solid at ordinary temperature, the stearoptene, and one which is liquid at low temperatures, the elaoptene (fromoil, andvolatile.3)

The result of this was that the solid deposits from volatile oils were thereafter designated alternately stearoptene as well as camphor. Up to this day the misuse of the term camphor has not ceased as becomes apparent from such words as cedar camphor, cubeb camphor, juniper camphor, etc.

Soubeiran and Capitaine4) made matters even worse by applying the term "liquid camphor" to the liquid hydrogen-chloride addition products of the terpenes. After it had been shown that true camphor contained oxygen, the term camphor in its generic sense was also applied to other oxygenated constituents of volatile oils though they were liquid.

1) Journ. de Pharm. 4 (1818), 5.

2) Berzelius, Lehrbuch der Chemie. 3. ed. 1837. vol. 6, p. 580. 3) Berzelius, Lehrbuch der Chemie. 3. ed. 1837. vol. 6, p. 580. 4) Liebig's Annalen 34 (1840), 311.

In 1833 Dumas published an article entitled Oder die vegetabilischen Substanzen, welche sich dem Campher nahern und uder einige atherische Ole.1) Although a number of important observations of rather striking properties of individual oils had been made, the systematic study of the volatile oils may be said to have begun with the analysis of a number of stearoptenes by Dumas. He suggested the following classification of volatile oils:

1. Those that consist of carbon and hydrogen only, like turpentine oil and oil of lemon;

2. Those that contain oxygen, like camphor and anise oil;

3. Those that contain sulphur,2) like mustard oil, or nitrogen, like oil of bitter almonds.

The elementary analysis of solid peppermint oil, camphor and solid anise oil revealed the composition C5H101/2 C5H81/2 0 and C6H61/2 0. By doubling these formulas of Dumas the modern formulas for the respective substances are obtained.

Of the oxygen-free oils, he analyzed turpentine oil and the hydrocarbons of lemon oil, verifying the earlier results of Houtton-Labilliardiere. During the years 1833 - 1835, Dumas published further contributions on the subject of volatile oils, several jointly with Pelouze and Peligot. They pertain to artificial camphor (pinene hydrochloride), mustard oil, cinnamon oil, terpin hydrate, orris oil, pepper oil, oil of juniper berries and others.

Almost simultaneously with the first publications by Dumas, Blanchet and Sell3) published the results of their investigation which had been carried out in Liebig's laboratory and which involved in large part the same substances studied by Dumas. The most noteworthy result of these investigations is the recognition of the identity of the stearoptene from fennel oil with that from anise oil.

Several years later, in 1837, the highly important and very interesting results of Liebig and Woehler's work on bitter almond oil were published.1) As early as 1802 Schrader and Vauquelin had discovered hydrocyanic acid in the distillate of bitter almonds. In 1822 Robiquet showed that no volatile oil preexisted in the almonds, and with Boutron-Charlard he had prepared amygdalin in 1830. They had not succeeded, however, in preparing bitter almond oil from amygdalin. That amygdalin is decomposed by emulsin into benzaldehyde, hydrocyanic acid and sugar was demonstrated by Liebig and Woehler. They also point out that the manner of formation of mustard oil must be closely related to that of bitter almond oil, for the mustard seeds deprived of their fatty oil possess no odor, this being produced only when water is present. The investigation of mustard oil by Will-) in 1844 substantiated this supposition.

1) Liebig's Annalen 6 (1833), 245.

2) The fact that mustard oil contains sulphur was recognized by Thibierge in 1819 (Journ. de pharm. 5, pp. 20, 439 and 446; Trommsdorff's Neues Journ. d. Pharm. 4, II. p. 250). That sulphuretted hydrogen is given off during the distillation of several umbelliferous fruits, such as caraway, dill, fennel, etc., was pointed out by L. A. Planche of Paris in 1820. (Trommsdorff's Neues Journ. d. Pharm. 7, I. p. 356.)

3) Liebig's Annalen 7 (1833), 154.