Examination of Essential Oils. 



The spectrum, however, terminated a little beyond 18 Cd only after 

 diluting 30,000 times. (Diagram 7.) 



Oil of Cubebs (Mr. Carries). — There were two portions of this oil, 

 one boiling at 260—265°, the other between 266—275°. The first was 

 examined, when diluted 1,000 and 5,000 times ; the second portion 

 after diluting 5,000, 10,000, 20,000, and 50,000 times. As far as line 

 Cd 17 the spectrum was freely transmitted, but a dilution of 10,000 

 times only feebly transmitted the more refrangible rays. (Diagram 7.) 



Oil of Calamus (Dr. Gladstone). — This oil belongs to the group of 

 substances with the formula C 15 H 24 . The portion boiling at 260° 

 was photographed. It yielded spectra after diluting ],000, 10,000, 

 20,000, and 30,000 times, and throughout exhibited the same absorp- 

 tive power, or nearly so, as that displayed by the oil of turpentine of 

 highest boiling-points. (Diagram 7.) 



Otto of Citron (Dr. Gladstone). — On the second distillation, two- 

 fractions were separated : the first boiled between 110° and 200°, the 

 distillate containing at first a little water ; the thermometer then rose 

 rapidly to 200°. The second fraction boiling between 200° and 245° 

 was photographed. This is one of those substances exhibiting a 

 strong absorption, even after dilution with alcohol to 20,000 times its 

 original volume. (Diagram 7.) 



Oil of Patchouli. No. L (Obtained by Dr. Gladstone from Mr. E. 

 Atkinson.) — On distillation, the three principal fractions boiled at the 

 following temperatures : — 



1st. 250—259° ; distillate turbid. 

 2nd. 259—275°. 



3rd. 275—290° ; this portion was blue. 



4th. 290 — 360° ; this appeared to yield a blue vapour. 



The second portion was photographed after diluting 1,000 and 5,000 

 times. (Diagram 8.) 



Patchouli. No. 2. — This blue oil was rectified, and the portion 

 boiling between 275° and 277° was photographed after diluting 

 5,000, 8,000, 10,000, and 50,000 times. 



A very distinct absorption band was noticed lying between lines 

 12 and 17 Cd. (See diagram.) 



Perfect transparency to the more refrangible rays was not obtained 

 by a dilution with 50,000 volumes of alcohol. This blue oil may be 

 considered a benzene derivative, since it yields an absorption band be- 

 tween the lines 12 and 17 Cd., and is highly coloured.* (Diagram 9.) 



Oil of Patchouli. No. 3. — Photographs of solution containing 2 * , 



* Ali organic colouring matters of which the constitution is known are benzene 

 derivatives in the sense that naphthalene and anthracene are benzene derivatives. — 

 W. N. H. 



