BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 557 
Fig. 13. 
The cui’ve for thiopheii, C^H 4 ,S, is considerably to the right of that for ethyl sul¬ 
phide, C 4 ,H 2 oS, and exemplifies the probable effect of the ring grouping of atoms in 
increasing the viscosity constants {vide infra). 
Aldehydes and Ketones. 
Observations were made on acetaldehyde and four ketones, viz., dimethyl ketone, 
methyl-ethyl ketone, diethyl ketone, and methyl-propyl ketone. Fig. 14 represents 
the results obtained. 
Fig. 14. 
Aldehyde and the ketones give curves which closely resemble one another, and in 
which dy/dt is very small. The curves follow regularly in the order of increasing 
molecular weight. Methyl-jjropyl and diethyl ketones give curves of almost the same 
shape, the latter lying uniformly to the left of the former; unlike the dichlorethanes, 
the symmetrical compound has in this case the smaller viscosity at the same tempera¬ 
ture. It should be stated, however, that the validity of this conclusion may be 
