CHEMISTRY: GOMBERG AND SCHOEPFLE 
459 
as benzene, nitrobenzene, etc. which freeze at temperatures around 
0°-5°, is between 480 and 485. A computation from these molecular 
weight determinations indicates that triphenylmethyl exists in the mono- 
molecular state to an extent of 17% in naphthalene at 80°, while to 
considerably less than 5%, if at all, in benzene at 6°. Schlenk and Mair^ 
determined the molecular weight of triphenylmethyl in benzene by the 
ebullioscopic method, and found that at the temperature of the boiling 
point of benzene, also about 80°, the hydrocarbon is dissociated in the 
monomolecular phase to the extent of 23.3-29.9% with approximately 
a 2 % concentration. SchmidHn^ calls attention to the fact that it is 
very difficult to obtain an absolutely pure sample of triphenylmethyl and 
that samples prepared by shghtly different methods often differ consider- 
ably in purity. Therefore he suggests the possibility that the varia- 
tion between the molecular weights found by Schlenk with the ebullio- 
scopic method and by Gomberg and Cone with the cryoscopic method 
may be due to differences in the degree of purity of the samples used. 
Accordingly, he constructed a special apparatus containing two thermo- 
meters, by means of which he could determine the molecular weight in 
benzene first by the ebullioscopic method and then by the cryoscopic 
method on one and the same sample. However, the molecular weights 
of triphenylmethyl found by the two methods showed no appreciable 
difference in value, and therefore no change in dissociation between the 
temperatures of 6° and 80° was noticeable. 
With regard to the influence of concentration upon the degree of dis- 
sociation of hexaphenyle thane, an examination of the results obtained 
by various investigators fails to reveal a concordant influence of this 
factor. Neither molecular weight determinations nor the application 
of optical methods^ have suppHed information of a sufficiently decisive 
nature to warrant us in drawing any conclusion as regards the concentra- 
tion influences affecting the equihbrium between the dimolecular and 
the monomolecular triarylmethyl. 
Relation Between Dissociation and the Nature of the Aryl Groups. — 
Although triphenylmethyl, the first and simplest representative of the 
triarylmethyls, was found to be largely in the dimolecular state, some 
of its analogs were found to exist to a large extent as monomolecular. 
Among the first triarylmethyls of this kind was the series containing 
/?"biphenyl groups : 
(C6H5).C-(C6H4-C6H5), (C6H5)C(C6H4-C«H5)2, C(C6H4-C6H5)3. 
Schlenk and his co-workers concluded from the measurements of the 
molecular weight by the cryoscopic method with benzene as a solvent, 
