BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 555 
The same effects as in the case of the dibromides are here traceable, the introduction 
of a second atom of chlorine exercising a marked increase in the viscosity constants. 
The curve for dichlormethane occurs to the right of the normal propyl curve, and 
both the dichlorethanes are to the right of the isobutyl curve. 
Fio-. 11. 
o 
The distance between the curves for the dichlorethanes indicates a difference in the 
characters of the two substances which seems almost too great to be accounted for by 
the mere difference in their chemical constitutions. Probably the molecular com¬ 
plexities of the two substances may not be the same. Schiff’s values for the surface 
tension of ethylene chloride give, however, no indication of molecular aggregation, 
and as yet there are no other data on this point. It is noteworthy that the curve of 
the symmetrical isomer lies to the right of that of the unsymmetrical isomer, a 
position analogous to that of the curve for symmetrical ethylene dibromide as 
compared with that of propylene dibromide. 
Pohj-chlorinated Com 2 )ounds. 
Measurements were made on the di-, tri-, and tetra-chlormethanes, and also on 
tetrachlorethylene. The curves obtained are represented in fig. 12. The curves for 
the chlormethanes follow one another in the order of their molecular weights. The 
distance apart of the curves for the tri- and tetra-chlor compounds is much greater 
4 B 
O 
