benzine, and to change the yellow (hydrated) oxide of iron to the red (anhydrous) oxide, which is inert and harmless. Objection is made to this method of cleaning steel because of the expense of it.

The sand-blast seems to offer the most rapid and economical means of preparing structural steel to receive a coating of paint. It leaves the metal not only clean, but fairly dry-an important and essential condition if a receptive surface is to be secured. The painting of the metal should follow immediately after the cleaning is done, as cleaned metal will corrode under ordinary atmospheric conditions much more rapidly than uncleaned metal. It is argued that "aside from the chemical or scientific value of sand-blasting there is a very serious question of its effect upon the eyes and lungs of the operator."   It  is  further  argued  that  the