ME. C. GEEYILLE WILLIAZMS 0:^" ISOPEEXE AXD CAOrTCHTN'E. 
246 
composition is that of isoprene plus oxygen. If sufficient care be taken, the oxidation is 
perfectly definite. A specimen prepared with every precaution, and immediately analysed, 
afforded, on combustion with oxide of copper and oxygen gas, the annexed numbers : — 
0-1796 grm. gave 0-5186 carbonic acid and 0-1732 water. 
Converting these values into per-centages, we have — 
Experiment. 
Calculation. 
Carbon . , 
, . 78-8 
'cio 
60 
78-95 
Hydrogen . 
, . 10-7 
Hs 
8 
10-52 
Oxygen . . 
, . 10-5 
0 
8 
10-53 
100-0 
76 
100-00 
The above values at once indicate 
C"> O 
as the formula for the substance; the agreement of the numbers resulting £i-om the 
analysis with those of calculation appearing to show conclusively the perfectly definite 
nature of the reaction. 
As regards the true formula of this substance, there is reason to suppose that the 
expression O does not correspond to four volumes of vapoiu- ; but as it is not vola- 
tile without decomposition, and as its properties forbid any hope of its yielding com- 
pounds from which the true equivalent might be deduced, I am at present compelled 
to rest satisfied with obtaining the simplest arithmetical relation between the elements. 
The above-described substance is, it is believed, unique m its characters, whether we 
regard its composition as the directly formed oxide of a hydrocarbon, or the mode of its 
production by the influence of ozone. 
On Caoutchine. 
The formula derived by M. Himly from his experiments upon the oil boiling between 
171° and 173° was perfectly correct. The following numbers resulting from my analyses 
merely, therefore, confirm the old ones. 
Nos. II, and III. were made on two samples of caoutchine from gutta percha. No. II. 
boiled between 170° and 173°, and No, III. between 173° and 177°. 0\^ing to the 
large quantity of carbon deposited in the bulbs, I was obliged to bimi the fluid in open 
tubes, and use oxygen in excess at the termination of each analysis. 
1. 0-1808 grm, yielded 0-5828 carbonic acid and 0-1932 water. 
II. 0-1992 grm, yielded 0-6462 carbonic acid and 0-2214 water. 
III. 0-1974 grm. yielded 0-6362 carbonic acid and 0-2098 water. 
The above numbers, converted into per-centages, yield the following 'calues, which are 
placed parallel with the theoretical formula and the previous results of M. Himly : — 
