Cut up the goose into convenient pieces; trim off all fat and put aside for use later.
Mix the salt and saltpetre, and rub each piece of goose with the mixture.
Put the pieces of goose into an earthenware pot, cover with a cloth, and then with a piece of flat wood on top of which you put a fairly heavy weight.
Leave in a cool place to steep for 48 hours.
Now wipe the pieces of goose very thoroughly.
Melt the fat which you have previously put aside, adding, if necessary, a little lard, so that you have enough to immerse the bird completely.
Heat, bring to boiling point, and then simmer over a gentle heat until the meat is tender enough for a knitting needle to pierce a large piece of it quite easily.
Pieces of goose take about 1 1/2 hours to reach this stage.
When the pieces of goose are cooked and perfectly tender put them in a large jar, pour all the fat over them, straining it through a cloth.
The meat must be well covered by the fat.
Let it cool for 24 hours and solidify.
Then seal off the top with crushed rock salt.
Put a paper on top and a lid on the jar to seal it hermetically.
This preserve will keep in a cool place for several months.
Goose preserved in this way can eventually be served either just as it is or fried in its own fat, and sprinkled before serving with chopped parsley or a mixture of chopped parsley and garlic.
Serve potatoes with it, also fried in the goose-fat.
Duck, turkey, chicken and pork may be treated in this way too.