( 106 ) 
values found 46,1 and 1,84 the refraction lies between the one 
calculated for a monocyclic terpene (45,2) and that of an aliphatic 
terpene (46.9); the dispersion exceeds that of a monocyclic terpene 
by 28.6% and even that of an aliphatic terpene by 11.5%• I have 
noticed something similar *) with aliphatic terpenes with a conjugated 
system of double bonds. A similar configuration might be suspected 
in the structure of the substances obtained and something might be 
said as to the presence of a monocyclic terpene with two double 
bonds in a conjugated position. 
I have also investigated the action of bromine, hydrogen and 
potassium permanganate. The bromine absorption was carried on in 
carbon tetrachloride solution; one mol. rapidly absorbed two atoms 
of bromine, but (as shown by the decoloration) a third atom was 
absorbed but very slowly with evolution of hydrogen bromide. The 
bromide obtained was a colourless oil. The hydrogen absorption was 
carried on by passing the substance very slowly at 180° over active 
nickel in a current of hydrogen. The product of the reaction may be 
separated into three parts by fractionation, namely a first fraction 
with a low sp. gr. corresponding in odour with dimet,hyl-2-6-octane ’), 
a second (main) fraction boiling at 164°—166° (g% = 0,787), of the 
composition C 1# H 18 and a third fraction boiling at 166°—170°. 
Nearly the whole of the liquid passed over below 169°, the b. p. 
of hexahydro-p-cymene, which ought to have formed if a monocyclic 
terpene derivative of p-menthane had been present. 
The result of this reaction gives some insight into the nature of the 
products. Sabatier and Senderens were able to effect the hydroge¬ 
nation of bicyclic terpenes to hydrocarbons of the composition C 1# H 18 , 
whilst the monocyclic terpenes investigated all yielded the same 
hexahydro-p-cymene s ). In addition, I have also investigated a terpene 
with a 6- and 3-cycle in the molecule, namely, sabinene which also 
yielded a hydrocarbon C 10 H, 8 . The said hydrocarbons C 10 H 18 are all 
different., as different cycle-systems occur in their molecules. In all of 
them 1 have found a characteristic property; they are saturated 
towards potassium permanganate, but are rapidly attacked by bromine 
at the ordinary temperature. This reaction is shown in a very 
characteristic manner by dihydrosabinene. In the above mentioned 
hydrogenation product of the hydrocarbon from linanool, I also 
noticed this property from which it ought to be concluded that a 
bicyclic terpe ne occurs in the original product; if this is a single 
Rec. Trav. Ghim. 27, 432 (1908). 
2 ) G. J. Enklaar, Ber. 41, 2083 (1908). 
3 ) Ann. de Ghim. et de Phys. [8]. IV, 1905 p. 319. 
