CHEMISTRY: COM BERG AND SCHOEPFLE 
461 
'C6H4V 
6. CioHt-O 
a-Naphthyl-xanthyl. 
7. CeHs-O 
Phenyl-pheno-j3-naphtho-xanthyl. 
A determination of the molecular state, and consequently of the 
dissociation phenomenon, of these unsaturated compounds is the more 
pertinent in view of the limited number of radicals upon which such 
determinations have been conducted in the past. Further and, if 
possible, more certain evidence with respect to the dissociation of 
these hydrocarbons, and consequently with respect to the trivalency 
of carbon, is most desirable. 
Our aim has been to take every possible precaution to insure uni- 
formity and purity of the triarylmethyls to be used. As a check, 
the capacity for oxygen absorption and for peroxide formation was 
always resorted to, using part of the very same sample which served 
for the determination of the molecular weight. This is a very essential 
and one of the safest criterions for the purity of the products, the re- 
action being: 2 R3C -f- O2 = R3C— O— O— R3C. Also it was made 
certain that during the course of the determination the triarylmethyl 
suffered no deleterious isomerization due to the effect of the temper- 
ature (80°) of the solvent, naphthalene. Each experiment represents 
an individual preparation and in no case were two determinations 
of the molecular weight made upon the same sample. Moreover, 
the sample was never more than one day old, the free radical being 
prepared in the afternoon, allowed to crystallize over night, isolated 
the following morning and the molecular weight taken the same after- 
noon. The molecular weight determinations themselves were carried 
out in an atmosphere of hydrogen, oxygen being completely excluded 
from the whole apparatus. The details regarding the preparation of 
the pure compounds and the method used in the molecular weight 
determinations will appear shortly in the Journal of the American 
Chemical Society. 
The triarylmethyls were studied from two points of view. (1) 
The molecular weight of every triarylmethyl was determined within 
a fairly wide range of concentration, from 1% to 6%, in order to deter- 
mine the effect of concentration upon the degree of dissociation. (2) 
From a comparison of the degree of dissociation of various traryl- 
methyls, under the same conditions of solvent, concentration and tem- 
perature, it was hoped that something would be learned regarding the 
