Difficult to melt ice recipe

How to make really hard to melt ice found!

To make the ice melt easily.
1, Making water not as much as possible in the air

2 A slow freeze Keep this one.

Steps:

1. About the system of Government 1
   Tap water contains a lot of air!
   It is quickly melt ice touches in the air, only.
   So, to boil tap water cool for at least.
   Then, is that since pulling out of the air in the water, difficult to melt ice.
   From mineral water, boiling, freezing

   Because fewer impurities than clear ice is

   About the 2??
   Is because it had frozen slowly, larger crystals.
   Than small crystals together to
   Time takes big Crystal is tied is solvable.

   Put the ice tray bag slowly freezes. Can you weaken the freezer temperature (increase) is the point.