BETWEE?^ THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 597 
The introduction of a carbon atom and the occurrence of a double linkage, which 
takes place in passing from tetrachlormethane to tetrachlorethylene, is followed by a 
considerable lowering of the viscosity coefficient, viz., 107 units. 
This effect is almost the same as that produced on passing from methyl alcohol to 
acetaldehyde, where 0 is replaced by CO. It must not be forgotten, however, that in 
the ca.se of methyl alcohol the result is affected by molecular complexity. 
Isomers. 
Normal and Iso Compounds. 
Normal. 
Difference. 
Iso. 
'/• 
V- 
Pentanes . 
200 
- 3 
203 
Hexanes. 
204 
- 1 
205 
Heptanes. 
199 
1 
198 
Propyl iodides. 
3.53 
- 6 
359 
Propyl bromides .... 
325 
- 4 
329 
Propyl chloiides .... 
274 
- 1 
275 
Butyric acids. 
309 
2 
307 
Propyl alcohols. 
463 
-28 
491 
Butyl alcohols. 
405 
-47 
452 
Excluding the alcohols, the viscosity-coefficient of an iso compound is either 
slightly greater than, or almost equal to, that of the corresponding normal compound. 
In the seven cases cited, the coefficient of the iso compound is, on the average, 
greater by some two units. In the case of the alcohols the differences are in the same 
sense, but have considerably larger values, viz., 28 and 47 units. 
Butyl Alcohols and Ethyl Ether. 
>1- 
Difference. 
Normal butyl alcohol. 
405 
47 
Isobutyl alcohol . 
452 
114 
Trimethyl carbinol. 
566 
1 Ethyl ether. 
205 
