586 Wisconsin Academy of Sciences, Arts, and Letters. 
and Silver lakes the coefficient of absorption rises very slowly 
in this region. 
All of the lakes rated at 18-22 have closely similar curves 
of the first type. 
Fig. 10. Absorption curves of lakes rated 14 on the color scale: 
1, Mouse lake; 2. Nagawicka lake; 3. Pine lake; 4. Otter lake; 
5. Silver lake. 
Thus the discrepancy between rating on the platinum-cobalt 
scale and the form of the absorption curves is most conspicuous 
in the lower numbers of the scale. It means two things; 
first, that it is not easy to apply the scale exactly to these low 
colored waters. Probably, Devils lake might have been rated 
somewhat lower than 8 with equal or greater accuracy. Second, 
and far more important, the platinum-cobalt scale, like any 
other scale for rating colors of lakes, matches the color of var¬ 
ious waters with varying degrees of accuracy. Doubtless, 
the matching for this scale is most correct in the lakes with 
