advantage of DME (POLAROGRAPHY) VERY IMPORTANT 

• Its surface area is reproducible which eliminates passivity or poisoning effect
• there is a large hydrogen overvoltage of mercury,so reduction of even alkali metals 
• surface area can be calculated from weight of drop
• diffusion current assumes steady value immediately and thus reproducible 

limitation

• ease with which it is oxidised
• limited use

DIFFERNCE BETWEEN SACCHARIMETER AND POLARIMETER

• Saccharimeter uses white light and can be use only for sugars while polarimeter is operated with sharp monochromatic light
• polarimeter can used for determination of optical rotation of any solution including sugars but saccharometer sugar determinations are basis of internationally accepted sugars degree

spectral wavelength and colors corresponding 
range of wavelength  (color absorbed) 
400-450(violet)----------> yellow green (supplementary observed color of solution)
450-480(blue)------------>yellow
480-490(green blue)--------> orange 
490-500(blue green)----------> red
500-560(green)----------------> purple
560-575(yellow green)-----------> violet
575-590(yellow)-------------------> blue
590-625(orange)---------------------> green blue
625-750(red)--------------------------> blue green