1. Introduction. 
When, more than a quarter of a century ago, I selected oil of 
turpentine as the object of my first two scientific investigations i), drugs 
and galenic preparations containing essential oils enjoyed a high repu- 
tation in the medicinal treasure. But there came a time, when a desire 
arose to place the medicinal treasure on a more scientific basis. From 
that moment the alkaloids, the glucosides, an enormous number of 
compounds of iron, mercury, and iodine, the artificial febrifuges, arti- 
ficial narcotics, and artificial antiseptics, played such an important par4 
in pharmacological instruction that no time was left for the discussion 
of the old plants containing essential oils, and of the preparations made 
from them. The teachers of this branch of knowledge mentioned 
perhaps once or twice, at the end of the lecture : "There are unfortun- 
ately in the medicinal treasure still a large number of antiquated re- 
medies which have been derived from popular medicine, but which 
are nearly all superfluous and antiquated. I may be excused from 
enumerating and demonstrating these". But this they merely said as 
a matter of form for the sake of doing their duty. 
In spite of being thus degraded to the position of a pariah in the 
eyes of Science, the aethereo-oleosa have continued to play a useful part in 
the practice of our daily life, and in the last decade they have be- 
come even more important. This advance was due to the fact that 
Chemistry, independent of Medicine, turned its attention towards the 
production and the study of the individual substances contained in the 
essential oils, and only thereby rendered the analysis of their actions 
possible. Up to that time it was no doubt know^n in Pharmacology 
"that the essential oils could not all be tarred with the same brush"; 
— but all the rest, apart from the experience gained at the sick-bed^ stood 
on an uncertain foundation. At the present day, when most of the 
essential oils which here come under consideration have been accurately 
^) Beitrage zur Terpen tinolwirkung. Erster Teil. Zeitschrift fiir die gesamten 
Naturwissenschaften fiir Sachsen und Thiiringen. Edited by Professor Giebel, 
Vol. 49 (1876), I. — Beitrage zur Terpentinolwirkung. Zweiter Teil. Thesis. 
Halle o./S. 1877. 
