244 
m. C. GEEYILLE WILLIAMS OS ISOPEEATl AXD CAOrTCHENT:. 
Although the boilirfg-point indicated the value of n to be not gi-eater than 2, it is 
plain that the fluid might possibly have a higher formula. The atomic "weight was 
therefore determined from the density of the vapour, assuming it to possess the usual 
condensation to four volumes. 
The following were the numbers obtained : — 
Weight of 
fluid. 
Temperature 
of vapour. 
Difference 
of level, 
in millims. 
Pressing column 
of water reduced 
to millimetres 
of mercury. 
Atmospheric 
pressure, in 
millimetres. 
Observed 
volume, 
in cubic 
centimetres. 
Densitr of 
vapour. 
0-0882 
O 
43 
126 
25 
764 
36-7 
2-47 
0-0848 
58 
124 
25 
765 
37-8 
2-40 
0-0882 
61 
119 
24 
764 
38-6 
2-46 
0-0964 
64 
99-1 
31 
764-4 
41-0 
2-45 
0-0882 
68 
113 
24 
764 
39-4 
2-43 
The formula H® requires 
10 volumes Carbon- vapour . . . 0‘8290 . 10 = 8-2900 
16 volumes Hydrogen 0-0692 . 16 = 1-1072 
9-3972 
= 2-3493 
4 
Mean of experiments. Tlieorj, C® II®=4 volumes. 
2-44 2-3493 
The values condensed into the above Table are not intended to represent the influence 
of temperature upon the density. They are cited to show unmistakeably the formula 
of the hydrocarbon. It will be seen at a glance that all the determinations except the 
second are higher than is consistent with perfect accm-acy. This is dependent upon the 
extreme tendency of the fluid to undergo oxidation, and thus, to a greater or less extent, 
lose its volatility. It was some time before the full extent of this tendency was ascer- 
tained and precautions taken to prevent it, and in the meantime the densities came out 
too high. It was found, however, that if distilled over sodium only a few minutes before 
determining the volume of the vapour, the result obtained was sufficiently accurate 
for the purpose required. The second of the experiments in the above Table was 
made with this precaution, and the resulting number was only O-Qo in excess of the 
calculation. 
I have given the substance thus examined the name of iso^rene. It would have 
been more grateful to me to have retained one of the names gb’en by the previous 
observers, if that course had been possible ; but Himly has not named the fluid dis- 
covered by him boiling between 33° and 44°, and the term caoidchhie having been 
applied by Bouchaedat to a fluid boiling at 14°-5, I could not adopt it; moreover, it is 
too like caoutchine. 
The specific gravity of the fluid at 20° C. was found to be 0-6823. 
It will be seen that none of the hydrocarbons examined by Geegory, Himly, or 
