binding properties. Concentrated driers are obtained by heating linseed oil with excessive weights of lead and manganese oxides until the product becomes viscous, like sticking-plaster. Liquid driers are concentrated driers thinned out while hot with naphtha or spirits of turpentine; sometimes rosin or better resins are added to give viscosity. The function of painters' japans, etc., should be to "hurry up" the drying of the binder, yet the lower grades are often used as extenders or cheapeners.

Metallic Soap.— The principal constit- uents of linseed oil (about 85 per cent.) are the glycerides linolein, linolenin, and isolinolenin. They are "esters of glycerine and linolic, linolenic, and iso-linolenic acids"; and it is to them that the drying of linseed  oil  is  due.  These glycerides are very easilysaponified.  The  soaps  formed