To extract the clams from the shells, wash them in cold water, and put them all into a large pot over the fire, containing half a cupful of boiling water; cover closely, and the steam will cause the clams to open; pour all into a colander over a pan, and extract the meat from the shells.
Put a quart of the clams with their liquor on the fire, with a pint of water; boil them about three minutes, during which time skim them well, then strain them. Beard them, and return the liquor to the fire, with the hard portions of the clams (keeping the soft portions aside in a warm place), half an onion (one ounce), a sprig of thyme, three or four sprigs of parsley, and one large blade of mace; cover it, and let it sim mer for half an hour.
In the mean time make a roux, i. e., put three ounces of butter (size of an egg) into a stew-pan, and when it bubbles sprinkle in two ounces of flour (one heaping table-spoonful); stir it on the fire until cooked, and then stir in gradually a pint of hot cream; add this to the clam liquor (strained), with a seasoning of salt and a little Cayenne pepper; also the soft clams, without chopping them. When well mixed, and thoroughly hot (with-out boiling), serve immediately.