Bring 12 cups water and 2 tablespoons salt to a boil in a lobster pot or large, wide stockpot.
Pick up each lobster firmly, holding the back of the body behind the claws. Add 2-4 lobsters to the pot; they should fit snugly, but not stacked. Cover, and cook for 18 minutes. Remove and repeat with remaining lobster. Let cool slightly before cracking and removing meat, about 20 minutes.
Heat butter in a small saucepan over low heat. Cook, skimming solids that rise to surface. Season with salt, then pour into small ramekin or a large dish, leaving behind any solids on the bottom; a clear, golden liquid will be left. Keep butter warm.
Place 1 lobster on the cutting board. Twist tail from joint where it meets the body, Cut tail in half down the center, keeping shell halves intact. Pull each tail half from its shells. Twist claws from body and discard body. Separate claws form knuckles. Crack knuckles, and remove meat. Discard knuckle shells. Grasp the thumb of claw, and bend it back to snap it off. Crack claws, and remove meat. Discard claw shells. Repeat with remaining lobster.
Arrange lobster pieces on a platter and serve with butter and lemon.