We have received a small box from C. C. Halladay, of Utica, 111., containing incrustations three-eighths of an inch thick taken from the inside of a steam boiler. He says, in a letter accompanying them :—" The agent we use to destroy the scale is slippery elm— thanks to your journal for the information. As long as I live, you will be sure of one subscriber, and all others that I can induce to subscribe." We do not doubt that twice the quantity of fuel will be required to generate steam in any boiler having such incrustations, in comparison with the quantity consumed beneath a clean boiler.