For a milled soap the large slabs are cut into narrow oblong shapes by means of the cutting table to readily pass into the feeder of the _chipper_, the chips being spread upon _trays_ and dried in a _dry house_ until the moisture content is approximately 15%. The process of milling is accomplished by passing the dried soap chips through a _soap mill_, which is a machine consisting of usually three or four contiguous, smooth, granite rollers operated by a system of gears and set far enough apart to allow the soap to pass from a hopper to the first roller, from which it is constantly conveyed to each succeeding roller as a thin film, and finally scraped from the last roller to fall into the _milling box_ in thin ribbon form. These mills are often operated in tandem, which necessitates less handling of soap by the operator. The object of milling is to give the soap a glossy, smooth finish and to blend it into a homogeneous mass. The perfume, color, medication or any other material desired are added to the dried soap chips prior to milling. Some manufacturers use an _amalgamator_ to distribute these uniformly through the soap, which eliminates at least one milling. When a white soap is being put through the mill, it is advisable to add from 0.5% to 1% of a good, fine quality of zinc oxide to the soap, if this substance has not been previously added. This serves to remove the yellowish cast and any translucency occasioned by plodding. Too great a quantity of this compound added, later exhibits itself by imparting to the soap a dead white appearance. Inasmuch as the milling process is one upon which the appearance of a finished cake of toilet soap largely depends, it should be carefully done. The number of times a soap should be milled depends upon the character of a soap being worked. It should of course be the object to mill with as high a percentage of moisture as possible. Should the soap become too dry it is advisable to add water directly, rather than wet soap, since water can more easily be distributed through the mass. As a general statement it may be said it is better policy to overmill a soap, rather than not mill it often enough.