All leather contains more or less oil. When the amount of oil decreases the leather becomes harder, less pliable, and shows a tendency to crack. It loses its elasticity and breaks more readily under sudden strains. Exposure to the sun evaporates the oil and exposure to the rain washes it out, both conditions tending in the long run to bring the same result, namely, hardening and stiffening of the leather. Accumulations of foreign substances are very injurious for they tend to absorb the oil from the leather underneath, leaving it dry and hard, or they retain moisture on the surface, prevent the air from getting to it and rot the leather. Also many substances such as perspiration and excretion from the horse contain chemicals which are very injurious. For these reasons all leather must be kept clean. The cleaning agent used is castile soap with water. All pieces should be taken apart and as much dirt and dust as possible removed with a damp sponge or cloth. All remaining dirt is then removed by washing with castile soap and water. In doing this always use as little water as possible. Wring the sponge out nearly dry, rub it on the soap and work it with the hands until a thick, creamy lather is formed. Then scrub the leather thoroughly until all dirt is removed. Special care should be taken around spots that have been in contact with metal perspiration or excreta. If there is an old accumulation of dirt a soft stick may be used to scrape this off. Never allow a knife or a piece of glass to be used or any sharp edged instrument. After all dirt is removed run the sponge in one direction, all the way along the leather to remove all remaining dirt and extra lather. Never allow the pieces to be rinsed off in a bucket of water. Metal parts should be washed thoroughly and dried and if necessary any rust removed with a crocus cloth. Although as little water as possible is used some of the oil in the leather will certainly be washed out, and, to keep the leather in proper condition, it must be replaced. After an ordinary cleaning this is normally done by an application of saddle soap. Saddle soap is not a cleaning agent—only a dressing for leather. It contains enough oil to replace, if properly applied, all loss through ordinary use. It is used in the same manner as castile soap, in the form of a thick, creamy lather, rubbed well into the leather and allowed to dry. The leather should be well rubbed with the hands while drying, to keep it soft and pliable, and to work the oil in. Always allow it to dry in the shade, preferably for several hours, and never assemble pieces, especially fastening straps into buckles until thoroughly dry. Oil is never applied directly to leather unless it has become so hard and dry that saddle soap is not sufficient to soften it. There is only one oil issued for that purpose. That is “Neat’s Foot Oil.” This should only be applied to the flesh side of the leather and very lightly. Several light applications