320 Wisconsin Academy of Sciences , Arts and Letters. 
liams and of Bouchardat pertaining to the decomposition of terpenes at. 
high temperatures. In an article 12 (1884) he makes the following very 
important claim: “ There is no doubt that the di-isoprene of Bouchar¬ 
dat and the dipentene which I have just described, are identical with 
terpilene, the optically inactive hydrocarbon into which the terpenes 
and citrenes are convertible.” 
In 1886 Watts 31 showed dipentene (called by him “citrene,”) to be 
present in the oil of the leaves from citrus limetta. He states that it 
resembles “ citrene ” (+limonene) very much, but behaves differently 
toward polarized light. 
Bouchardat and Lafont 22 (1886) studied the action of chromic acid on 
leevogyrate pinene. Among other products they obtained a hydrocar¬ 
bon C 10 H 16 which boiled between 174-178°, [n] D = — 56° and combined 
with hydrochloric acid to form a “ chlorhydrate de terpilene ou de 
citrene” which melted at 47°, (dipentene dihydrochloride). It is quite 
evident that this hydrocarbon consisted of a mixture of limonene and 
dipentene. The “ isoterpenes ” of Flawitzky 23 obtained by the dehydra¬ 
tion of the so-called “ terpenhydrate” (evidently mixtures of the opt. in¬ 
active terpinene with the opt. active ones,) are no doubt similar mixtures* 
Bouchardat and Voiry 24 (1888) bring nothing new when they state that 
dipentene dihydrochloride when heated with alcoholic potash yields a 
“ carbure terpilenique ” (impure dipentene). This fact simply shows 
that the deplorable custom of dishing up old facts with new names has 
not entirely ceased 25 . In his articles “ Sur l’essence d’Eucalyptus 
globulus ” 26 and “ Sur l’essence de cajeput” 27 Voiry even surpasses his 
master in scientific dishonesty. 
In a historical study of dipentene wormseed oil (Oleum cinae) must 
not be left unconsidered. It constitutes as it were a special chapter in 
the history of this hydrocarbon. It will, therefore, be necessary to turn 
back and study the development of our knowledge concerning dipen¬ 
tene ( “ cynene”) in connection with this oil. 
In 1841 Wohler 27 communicates the results of Volckel’s analysis of the 
oil. He states that “it does not appear to stand in any simple relation 
to santonin” but consists of a substance “C 9 H 15 O” admixed with 
small quantities of another oil.” In 1853 Volckel 28 assigned to the chief 
constituent of the oil boiling at 174-175° the formula “C :2 H 10 O.” In 
the following year in an article “ Veber das Cynen ” he treats of a hydro¬ 
carbon obtained by distilling wormseed oil repeatedly with anhydrous 
phosphoric acid. After successive treatment of the crude product with 
sulphuric acicl , water and chloride of calcium in order to “ purify ” ? it, 
the “cynen ” distilled completely between 173-175°. He assigns to it the 
formula C 13 H 9 . “Das Cynen ist demnach aus dem Wurmsamenol: 
C 12 H 10 O durch das Ausscheiden vom 1 Aeq. Wassertoff and 1 Aeg. 
Sauertoff als Wasser entstanden.” 
