For plate work, other than boilers, there is no more effectual initial coating than boiled oil. To be lasting, the plates should first be cleaned of all scale that is likely to become detached. When bars have to be riveted to plates, and where the atmosphere is likely to get between, the inner surfaces of both plates and bars should first be oiled over. One of the most fruitful causes of rapid deterioration in plate and constructional iron work, and which may have serious results,is the oxidation of parts of the structure that when put together are not get-at-able to be scaled or painted. This should be guarded against as far as possible in the manner suggested above.