We have received from Mr. E. Watson, of New Bedford, Mass., the description of a very safe and—as he states—an effectual method for removing scale or crust in steam boilers. It is as follows:—"Take ofl slippery elm or flax seed, or any mucilaginous vegetable matter, in quantity about three ounces to every horse power of the boiler—such as 24 ounces for an eight horse power engine—and throw it into the boiler. In a very short time afterwards, the scale will come off in flakes, and it can then be blown out by the blow-off cock. I have used the slippery elm with great success. Formerly I took two hours to get up steam, owing to the crust in the boiler. I now do the same in less than two-thirds of that time, and effect a great saving in fuel." We are aware that flax seed had been used for this purpose before, and can endorse its good qualities. Indian meal and sweet potatoes also answer the same purpose. We have never known of the slippery elm bark being used before ; but from its nature, we believe it accomplishes all that is claimed for it by Mr. Watson.