A way of checking your solution/solvent is use of a 
     Refractometer, temperature compensated.  These can give a 
     fairly accurate reading of solutions.  Leica, Inc., may be 
     able to help.  Leica manufactures refractometers.  We use a 
     refractometer to measure the percent concentration of our 
     solvent section and rinse stages of our semi-aqueous 
     cleaner.  Leica telephone number is (716) 891-0123.  Address 
     is shown below.
     
     Leica Inc.
     Microscopy & Scientific Instruments Division
     P.O. box 123
     Buffalo, NY 14240-0123