1903-4.] The Viscosity of Aqueous Solutions of Chlorides , etc. 237 
to warrant general conclusions, but some points worthy of notice 
may be referred to. 
The Efect of Temperature . — In every case the viscosity decreases 
with increase of temperature, but at different rates for the three 
salts, the rate for chloride beirfg greatest and iodide the smallest. 
It will be noticed, too, that a solution can at one temperature 
exhibit “ negative viscosity,” * and “ positive ” viscosity at 
another ; e.g. potassium chloride at each of the three concentrations 
is “ positive ” at 25° C. and “negative” at 15° C., while all the 
* The term “ negative viscosity ” has been frequently employed to express 
the fact that the viscosity of the solution is less than that of the pure solvent 
at the same temperature. 
