462 CHEMISTRY: COM BERG AND SCHOEPFLE 
influence of the various aryl groups upon the tendency of the ethane 
towards dissociation. 
Summary of the Results. — In the diagram are represented the curves, 
each curve based upon a number of molecular weight determi- 
nations, expressing the dissociation tendency of the hexa-arylethanes 
mentioned in this paper. The curves are plotted with the percentage 
of concentration as abscissas and the dissociation values, in per- 
centages, as ordinates. The values expressing dissociation were 
5 10 /.S 2.0 2.5 3.0 3.5 4.0 4.5 S.O 6r.5 6.0 
obtained according to the formula x = — where x equals the degree 
of dissociation, Mt represents the theoretical molecular weight of the 
hexa-arylethane and Mo the molecular weight actually found. 
1. In all instances, a steady and gradual increase of the molecular 
weight is noticeable as one proceeds from a 1% concentration of the 
radical to that of 6%. The generality of these results, and their 
uniformity, leave no room for doubt that we are dealing here with a 
phenomenon of molecular dissociation, wherein the products of dis- 
sociation are in equilibrium with the dissociating substance. An 
