WALLS OF PISS WORK.
[To THE EDITOR OP THE "{SPECTATOR."] Srn,—I wonder if, in your experiments with rammed earth walls, you have tried the effect of mixing the earth with a binder. In making dried sand cores for iron, steel, or brass castings it is the universal practice to mix the sand before ramming with a binding liquid. I think you would find a great gain in hardness through using starch or linseed oil mixed with the earth ; or one of the many core compounds supplied to foundrymen might be used. As regards quantity, the binder should be used sparingly or it will take a long time to harden naturally, and it must he well mixed. If enough be used just appreciably to stiffen a ball of earth pressed in the hand, the work of ramming will not be increased thereby, and the gain in the ultimate strength and hardness of the wall should be considerable. If the walls be skin-dried with artificial heat, the binder should cause a hard skin to form. An oil lamp of the compressed-air typo used by painters for burning off old paint, but larger, should be suitable for the
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