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THOMAS MIDGLEY, JR., ALBERTL. HENNEAND A. F. SHEPARD
Vol. 56
B was finely cut and allowed to soak in benzene as
Due to the limited amount of material available, double analyses were performed only in a few cases; with only one single exception the results checked within experimental error, and in the exceptional case, a third analysis secured the needed confirmation. TABLE I1 During the course of the fractionation it was SECONDARY FRACTIONATIONS Initial Weight, Splubility noted that vulcanization was still progressing and material Fraction g. S,% in CsHs that traces of unreacted accelerator were realso (As-1 13.7 0.058 Sol. ) moved by the solvents used in the fractionation. This explains why the total amount of combined [ Ai-4 8.0 ,043 s i . J sulfur was not constant after each fractionation. A-4, A-5 A24 2 . 8 .115 Sol. As the theoretical reasoning is based only on the and A-6 Az-6 3 . 9 .112 Sol. R& = 0.1153%S final results, when the sulfur concentration no A97 8 . 1 .117 Sol. longer changed, it is not affected by these details. A-7 and part
long as soluble matter diffused out. This soluble material (2.8 g.) was added to fraction A-7 and was also refractioned. The results appear in Table 11.
I
of B
1
As-8
4 . 0 .I79
Conclusion and Summary C. Analytical Procedure Partially vulcanized rubber has been fractionThe h e l y cut rubber samples were extracted ated into components in which rubber is combined with acetone in a Soxhlet apparatus for twenty- with increasing amounts of sulfur. The analyses four hours, swelled with benzene, soaked in alcohol of these fractions concur to indicate a molecular and freed of inorganic sulfides.' Blank runs weight of about 54,000 for the particular sample of demonstrated that this treatment was adequate. rubber used. Specimens of varied origin, can The sulfur content3 was determined by the thus have their molecular weight measured by procedure of Wolesensky. All results were cor- strictly orthodox chemical means. rected for parallel blank determinations. THEMIDGLEY FOUNDATION COLUMBUS, OHIO
(4) Stevens, Analyst, 40,275-281 (1915).
[CONTRIBUTION FROM
THE
RECEIVED SEPTEMBER 22, 1933
CHEMISTRY DEPARTMENT AT THE OHIOSTATE UNIVERSITY 1
Natural and Synthetic Rubber. XIV. A Structural Formula for Ebonite BY THOMAS MIDGLEY, JR., ALBERT L. HENNEAND A. F. SIIEPARD The ninth paper of this series' reported a list of compounds obtained by the pyrolysis of ebonite and stated that their correlation might elucidate the constitution of ebonite. The compounds positively identified, and their relative amounts, were benzene,
