313 



REPORT ] 872. 



^ 



The hydrocarbon with the lower boiling-point is evidently different from 

 the specimens di.s tilled at a higher temperature. These show a marked in- 

 crease in refraction, and one still more marked in dispersion, while there is 

 no corresponding increase in density; in fact they are fully up to, if not 

 above, any of the hydrocarbons of the Cj„ H,g type which I have examined. 

 jN'ow if the higher boiling-point be due to the admixture of a body of the 

 comiiosition of 0,^ H^^, it ought sensibly to diminish instead of increasing the 

 refraction, on the supposition that C and H have the usual values ; but if 

 this body belong to the group of aromatic hydrocarbons, and be, in fact, 

 cymene, it will liavc the precise effect which is found ; for cymene gave the 

 following numbers at 11° C. :— .specific gravity 0^S72 ; refractive index for 

 A 1^4S01; dispersion 0-0329 ; specific refractive energy O^SSOS. 



I have already remarked (Chem. Journ. Soc, 1870, p. 151) that aU the 

 terpenes give refraction-equivalents a little above the calculated amount, 

 and it might be supposed that this is due to the admixture of some cymene in 

 each instance ; but the fact of the same increased refraction occurring in the 

 cedrenes and colophene, which boil at a temperature far above that of cymene, 

 negatives this idea, unless it be supposed that these substances also contain 

 polymcrides of cymene, which is not impossible. 



The supposed polymcrides of myristicol gave the following numbers 

 (under them are given those previously determined for this compound) : — 



Prepared by 



Wright ... 



Ditto 



Ditto 



Gladstone 



Boiling- 

 point. 



212-218 



265-285 



above 300 



221 



Tempera- 

 ture of 

 experiment. 



ppccinc 

 gravity. 



24 

 25 

 30 

 20 



0-1)107 

 0-9906 

 10221 

 0-9466 



Refractive 



index I Dispersion, 

 for A. 



1-4757 



1-4958 

 r5319 

 1-4848 



■0271 

 •0362 



■0312 



Specific 



retractive 



energy. 



■5057 

 •4975 

 •5204 

 •5121 



The three supposed polymcrides are evidently different bodies ; but the 

 closeness of the specific refractive energies of the first two confirms the idea 

 of their being identical in ultimate composition. The third is only a httle 

 higher, which might easily be accounted for by a somewhat larger propor- 

 tion of hydrogen. 



_ The body derived from orangc-oil, which appeared to be analogous to this 

 higher polymeride of myristicol, Avas found to be like it in other respects also. 



