Density, and Temperature of Salt Solutions. 293 



fig*-. 5 & 6 (PL IV.), giving the relation between viscosity 

 and temperature, and viscosity and density. The three upper 

 curves in fig. 5 were for solutions of densities 1*188, 1*146, 

 and 1*101 at a temperature of 18° G. The lowest curve is for 

 water. In fio-. 6 the curves shown are for temperatures 0°, 

 10°, 30°, 50°, and 100° 0. Figs. 7 and 8 give the same 

 curves for calcium chloride. Straight lines were obtained 

 for the logarithmic values plotted as in fig. 3 for each of the 

 above temperatures. The values of u n" for sodium chloride 

 were found to be, when 



Ts= 0°C, n=:l-48, 



T= 10°, 7i = l-35, 



T = 30°, 71 = 1*10, 



T= 50°, 7i = l*09, 



T = 100°, 7i = l*075. 



From these figures it appears that ""w" decreases pro- 

 portionally to temperature from 0° to 30° C, but from 

 there the relative diminution becomes much less up to 100° C. 

 Values of //, were calculated from these values of n and were 

 found to agree exceedingly well with the experimental values. 

 It was desirable, however, to have a formula which would 

 involve the three quantities /x, p, and T. The above values 

 of " n " do not provide this, but it was found that, on 

 assuming "??, " to vary regularly in values from 1*4 to 1*0 

 between the limits 0° and 100° C, a quite accurate formula 

 was obtained in the form 



(p_ l)i-4- -004T =a(1-^'\ 



The same procedure was gone through with the calcium 

 chloride results. The values of " n " here varied regularly 

 from *95 to '85 as the temperature varied from 0° to 50° C. 

 This gives as the best formula between these limits 



(p_l)*95-002T = A(l -£-'). 



To obtain the value of A it is best to use the point at which 

 the solution has its highest density. Otherwise, if A be 

 obtained from a low density point the liability to error in 

 calculating the viscosities at higher densities is appreciable. 



The variation of A with T was next noticed. The figures 

 below give the actual values in each case for log. A. 



