RESEARCHES ON THE VOLATILE HYDROCARBONS. 153 
Determination of Boiling-point.— The quantity of material being quite small, this 
determination was made in a large test tube, with the usual precautions. It had not 
a perfectly constant boiling-point, the distillation ranging from .148°4 to 151°.6. 
Applying the proper corrections to the mean of these observations, gives, for the 
boiling-point of cumole, 151°.1, which is doubtless a little too high from the impracti- 
cability of making a complete separation with the small quantity of material employed. 
If the boiling-point difference between cumole and cymole, for the difference of C, H, 
in their elementary formule, is 30°, as there is every reason to believe, then the 
boiling-point of cumole should be 150°, as I have found the boiling-point of cymole to 
be but a fraction under 180°. 
Analysis. — 0.1700 gramme of cumole gave, by combustion with oxide of copper, 
0.563 of carbonic acid, and 0.1557 of water. 
Calculated. Found. 
Carbon, Crs "108 90.00 90.35 
Hydrogen, Hy 12 10.00 10.18 
120 100.00 100.53 
Determination of Vapor Density. — 
Temperature of balance, 3 : . : 3 : 17° 
Temperature of oil bath, . : . : : ‘ 203° 
Height of barometer, . . : F - 760.1™: at 15° 
Increment of balloon, F 2 ‘ P P . 0.4428 
Capacity of balloon, ‘ F : : ; ‘ 232 ec. 
Density of vapor found, . : F - 4.2008 
Theory C,3 Hy, = 4 volumes, . . 4151 
This determination, as well as the results of analysis, confirms, therefore, the formula 
which Gerhardt and Cahours had assigned to this body. I had anticipated a different 
result from this, inasmuch as the hydrocarbon from coal-tar naphtha, which I have 
called iso-cumole, boiling at 170°, or nearly 20° higher than cumole from cuminic acid, — 
had been found, as I have shown above, to have the formula C,, H,.. I am forced to 
the conclusion, therefore, that these two bodies are isomeric, and belong to different 
series. A preliminary examination of their behavior with reagents andicates that 
their chemical properties are also different. These will be. treated of on a future 
occasion, in Part III. 
VOL. IX. 24 
