A correspondent—Smith Groom, of Troy, N. Y.'—informs us, that his experience in the culture of potatoes has convinced him that about a handful of dry slacked lime placed in each hill tends to prevent the potato rot. The lime, he states, brings the potatoes earlier to maturity, and imparts to them a vigor which resists the attacks of the disease. An experiment with lime can be conducted by any of our farmers at a small expense, and if it does not prevent the potato rot, the lime will certainly enrich the soil for other crops.