C. GEEVILLE WILLIAMS ON ISOPEENE AND CAOUTCIIINE. 
247 
Experiment. 
Calculation. 
A 
Carbon 
( 
I. II. 
. 87-9 88-5 
III. 
87-9 
Mean. 
88-1 
Himlt. 
88-44 
f "■ 
C2® 
120 88-2 
Hydrogen 
. 11-9 12-1 
11-8 
11-9 
11-56 
16 11-8 
136 100^ 
I re-determined the vapour-density by Gay-Lussac’s process with the following 
result : — 
Temperature of vapour 
. . . 192° 
Weight of substance . 
. . . 0-1530 gramme. 
Difference of level 
Oil column reduced to milhmetres of mercury . . 22-0 millimetres. 
Atmospheric pressure 
Observed volume 
Density 
. . . 4-647 
The formula C^® H*® requii-es — 
20 volumes of Carbon-vapour 
0-8290.20 = 16-5800 
32 volumes of Hydi-ogen .... 
0-0692.32= 2-2144 
18'7944_4.Q9gg 
4 
Experiment. Himly. 
Calculation=4 volumes. 
4-647 4-461 
4-6986 
In consequence of the high temperature at which the experiment was made, it became 
necessary to introduce into the formula a correction for the elastic force of the vapour 
of mercury. 
On the Relation hetioeen the first and second Hydrocarbons produced 
by distillation of Caoutchouc. 
We are now, for the first time, in a position to understand the true connexion between 
the two hydrocarbons which have been described. The relation between them is the 
same as that between amylene and paramylene, and, as in the case of those bodies, the 
second is twice as hea\'y in the state of vapour as the first. 
The boiling-points of these bodies show very strongly the limited power of empirical 
formulse, even when (like those of Kopp and Geehaedt) founded on the accurate obser- 
vation of a vast number of bodies. Thus, amylene, H^®, containing four atoms of 
hydrogen more than caoutchine, should boil, according to Geehaedt’s law, 15x2 = 30° 
lower than that body, whereas the boiling-point is only 11° lower. Again, amylene, 
containing two atoms of hydrogen more than isoprene, should boil 15° lower, whereas it 
boils 2° higher. 
