Pan-fry bacon in a medium heavy skillet over moderate heat until crisp. Drain and crumble bacon; set aside.
Add onion and celery to pan and sauté over moderate heat until tender but not brown. In a large heavy saucepan, combine onions, celery, drained potatoes, chicken bouillon, clam juice and enough water to cover potatoes.
Cook, partially covered, over moderate heat for about 10 to 15 minutes or until vegetables are crisp tender.
Stir in 2 cups milk; simmer another 5 minutes and add seasonings to taste.
Reduce heat; add clams until they are heated through.
Combine the rest of the milk and flour, blending until smooth; stir mixture into chowder.
Heat chowder over low to moderate heat, stirring constantly, until chowder is bubbly hot and slightly thickened.
Add cooked bacon.
Adjust seasoning to taste.
If possible refrigerate chowder, covered, for 24 hours to develop flavors.