Re: Is there an optically clear,liquid which will not conduct electricity

I need more details on your experimental requirements to make any specific 
recommendation.

If the purpose of the liquid is heat transfer, the problem you will 
encounter is that substances which have good heat transfer characteristics 
typically are also good electrical conductors.  If you are planning on 
dropping the whole circuit in the liquid, only the natural convection will 
provide cooling.  This may or may not be adequate.

In situations where water cooling of electrically live components is 
required, deionized (DI) water is often used.  It has a resistivity on the 
order of 15 mega-ohm - centimeters.  Water is also a good heat insulator 
(that's why a wet suit works), so water cooling systems usually take 
advantage of convection by keeping the water flowing.  Distilled water, 
from a grocery store or pharmacy, is a "poor man's" DI water.

Unless your experiment MUST be submerged, I'd try forced air cooling first.  
(You can just use a fan.)  Monitor the temperature during longer and longer 
runs, and shut the system down at the first sign of an over-temperature 
condition.

If you begin researching different liquids for cooling, the electrical 
specification you are interested in is resistivity (units of ohm-cm) or its 
reciprocal, conductivity (units of mho/cm or Siemens/cm).  

If you have more specific questions, contact me at 
christopher.seaman@alcoa.com.

Good Luck,

Chris