What proves to retain heat the best fresh water or salt water

This experiment is about heat retention . The experiment compares the heat retention of salt has an affect of heat retention of water and see which one will cool the slowest.Two containers of fresh water were filled. I let them sat for approxiimately ten minutes.Two table spoon salt was added one of the containers of water and mark label salt water.On the first try no obvious difference could be observed temperature reading was 120 degree. On my second Trail i added two more table spoons of salt which made a difference.The salt water cooled in much less time than the tap water .The variable that was testing for out the experiment.was the amount of salt in water .The same starting thermometeters used through the experiment.When the waters reach 90 degrees celsiusus you start the the data collection. When the water starts to boil turn off the stove and see which type of water holds theheat the longest.