Mr. C, G. Williams on Isoprene and Caoutchine. 465 
annexed analyses. No. I. was from turpentine, II. and III. from 
caoutchine. 
Experiment. Calculation. 
ca — a 
i II. IIT. Mean. 
Carbon . . 89'2 89:5 89°5 89°4 OE 120.,.1,89:6 
Hydrogen . . 10°5 10°4 10°4 10°4 H“ 14 10:4 
134 100°0 
Agreeing perfectly with the formula C”? H™*, 
Paracymole. 
At the same time that cymole is formed, there is a production of 
an oil having the same composition, but boiling about 300°C. The 
author has provisionally named it paracymole. 
Action of Sulphuric Acid on Caoutchine. 
Sulphuric acid acts on caoutchine, converting it almost entirely into 
a viscid fluid like hévééne, at the same time a very small quantity of a 
conjugate acid is formed, having the formula 
ex H’ S? O°: ; 
the composition was determined from that of the lime salt, which on 
ignition, &c., gave a quantity of sulphate of lime equal to 8:3 per 
cent. of calcium; C* H” CaS? O° requires 8°5. 
The author considers the action of heat on caoutchouc to be merely 
the disruption of a polymeric body into substances having a simple 
relation to the parent hydrocarbon. He deduces this view from the 
similarity in composition between pure caoutchouc, isoprene, and 
caoutchine. 
The following Table contains the principal physical properties of 
isoprene and caoutchine :— 
Table of the Physical Properties of Isoprene and Caoutchine. 
Vapour-density. 
Name. Formula. | Boiling-point. a gee ee 
; Ghanieye Expt. Calculated. 
Tsoprene C10 HS Sf 0°6823 at 20° 2°44 2°349 
Caoutchine| C?? H16 UALS 0°8420 4°65 4-699 
In the calculations rendered necessary by the numerous vapour- 
density determinations contained in this paper, and more especiall 
in those ‘‘On some of the products of the Destructive Distillation of 
Boghead Coal,’ the author has so repeatedly had to ascertain the 
: 1 : 
value of the expression ——_—______, that he was induced to calcu- 
: P 1+0-00367 1" 
* (Note received July 27.) Both the cymole from turpentine and that from 
caoutchine were converted into insolinic acid by bichromate of potash and sul- 
phuric acid. The quantitative determinations made on the silver salt of the acid 
were almost theoretically exact. 
Phil, Mag. 8. 4, Vol. 21, No. 142. June 1861, 2H 
