Wash the rice well in a colander then put it in a bowl with 2 tb salt and lukewarm water to cover. Stir and let it soak overnight if you can, or at least for 1 hour. The longer the better. Fill a large saucepan with plenty of water, add 2 tb salt and bring to the boil. Sprinkle the drained rice in gradually and let it boil vigourly for about 4 to 8 minutes. The time depends upon the batch of rice but is ready when if you bit on a grain of rice you consider it to be slightly underdone, slightly harder than you would like to eat it. Drain quickly and rinse in lukewarm water. Put 2 tb butter and let it melt in the bottom of a pan, add all the rice and stir. Cover with 2 more tb of butter. Stretch a clean cloth over the top of the pan, put the lid on the top and lift the corners of the cloth up over it. Leave the rice to steam for 20 to 30 minutes over a very low flame. It should be cooked and separate. The crisp, brown, golden crust that forms at the bottom is considered a delicacy to be offered firs to guest. It is called 'dig'. Remove it with a spatula and serve separately.