ME. C. GEEVILLE WILLIAMS ON ISOPEENE AND CAOUTCHINE. 
249 
Quantity of Bromine water used in each experiment 20 cub. cents. 
Turpentine experiments. 
Caoutchine experiments. 
Difference in weight 
Oil of turpentine 
Difference in weight 
Caoutchine required 
Number. 
of the alkalimeter 
required to decolorize 
Number. 
of the alkalimeter 
to decolorize 20 cub. 
before and after 
20 cub. cents, of 
before and after 
cents, of bromine 
the experiment. 
bromine water. 
experiment. 
water. 
grm. 
grm. 
grm. 
grm. 
I. 
1-070 
0-1070 
I. 
1-119 
0-1119 
II. 
1-137 
0-1137 
II. 
1-088 
0-1088 
III. 
1-066 
0-1066 
III. 
1-083 
0-1083 
IV. 
1-024 
0-1024 
IV. 
1-074 
0-1074 
Mean of turpentine experiments. Mean of caoutchine experiments, 
0-1074 0-1091 
The identity of behatiour of caoutchine and oil of turpentine becomes very evident 
from the above experiments. The mean of the caoutchine results is nevertheless some- 
what higher than that of the turpentine series ; I ascribe this to caoutchine being, to a 
very slight degree, more sluggish in its action than oil of turpentine. 
On the Action of Bromine on Isoprene. 
I was exceedingly deshous of making experiments with weighed quantities of isoprene 
and bromine, in order to compare it with caoutchine. With this intent 1 made a solu- 
tion of it in alcohol, the strength being the same as the turpentine and caoutchine solu- 
tions. But it was impossible to obtain the wished-for results, owing to the manner in 
which the isoprene volatilized from the solution while pouring it into the bromine water. 
Isoprene combines explosively with bromine, even in presence of seventy or eighty 
times its volume of water. When the vessel containing the bromine at the bottom and 
the isoprene on the surface is shaken, union takes place with a loud noise and consider- 
able evolution of heat. A fine mobile bromine compound is the result. When coho- 
bated with excess of hydrate of potash, the greater portion is entirely decomposed, 
yielding a black mass, the distillate having the same odour as that evolved under similar 
circumstances by the higher olefiant, but accompanied by a substance so irritating to 
the eyes as to render it very distressing to manipulate. On placing about one ounce in 
a flask, and adding a fragment of hydrate of potash to neutralize it, an explosion took 
place, the fluid being thrown in my face and causing the most intense pain in the eyes. 
For several days no person could enter the laboratory without incurring great pain, 
accompanied by profuse lacrymation. My substance having in this unfortunate manner 
been lost, I am compelled to defer a more minute investigation of it. 
On the Conversion of Caoutchine into Cymole and Paracymole-. 
In Geehaedt’s classification of organic bodies, oil of turpentine is made to belong to 
the C)Tnenic series ; and it is even stated that Deville, by passing turpentine and carbonic 
acid through a tube heated to dull redness, obtained an oil which appeared to contain, 
MDCCCLX. 2 L 
