5o 4 SCIENCE PROGRESS 



150 and 200 C. — Prof. Harries 1 separated two other fractions, 

 one of which boiled at 147° — 150 C, sp. gr. "8286, and contained 

 no dipentene. For this hydrocarbon Harris revived the name 

 di-isoprene and he considered it to have the formula — 



CH 3 \ 



/C — CH, — CH 2 — CH = C — CH = CHj. 

 I 

 CH 3 



The other new fraction obtained had a boiling point 168° — 169° C, 

 sp. gr. '8309, and this also contained no dipentene. On 

 treatment with bromine a deep violet colour was produced. 

 Harries concluded that this was a new terpene, and in a 

 subsequent paper he advanced the view that instead of con- 

 taining a six-carbon ring like dipentene, the hydrocarbon 

 possibly contained a closed ring consisting of eight carbon 

 atoms. 



Heveene 



A large portion of the distillate boils above 200 C, but only 

 one definite fraction in this region seems to have been separated 

 and investigated. Alexander Bouchardat 2 in 1837 isolated a 

 neutral yellow oil boiling at 252 C, to which he gave the name 

 heveene. Its specific gravity was '921 and it combined directly 

 with the halogens, but the combination was generally accompanied 

 with evolution of the corresponding halogen acid. The con- 

 stitution of this hydrocarbon has never been worked out, and 

 very little is known regarding it. It is described in some places 

 as a sesquiterpene of the formula C 15 H 24 , and in others as a 

 diterpene — C20H32. The analytical results obtained by Bouch- 

 ardat did not quite agree either amongst themselves or with 

 either of the above formulae. The boiling point would appear 

 to indicate a sesquiterpene. 



Four years ago Fischer and Harries 3 made experiments on 

 the distillation of indiarubber in a vacuum. They found that 

 when the distillation is carried out under a pressure of '25 mm. 

 only a very a small quantity of isoprene or dipentene is 

 produced, the distillate consisting chiefly of high-boiling hydro- 

 carbons. 



We must thus assume that the low-boiling products are 



1 Per. 35 (1902), pp. 3260, 3266. 



2 Journ. de Pharm. vol. xxiii. (1837). 

 8 Bcr. 35 (1902), pp. 2162-3. 



