On page 140 of Hanna Winsnes’ cook book:

One pound of rice is rinsed in cold water, and then scolded in two to water litres of boiling water. Add five litres of milk; this is treated the same way as barley grøt but only boils for two hours; good quality rice can even be boiled faster.

If you fear that the rice could be acidic, it is safest to put it for a while in boiling milk to draw out the sourness. This milk must not be included in the grøt. If you want to boil the rice with water, only use four litres. When it is boiled stir in a spoon of butter. Some coriander is also good. They can be brought to the boil with the grøt, but must not boil for long in the grøt, as in may separate from their acidity.

Read about Hanna Winsnes and the first Norwegian cookery book.