CREOSOTE OIL FOR WOOD BLOCKS 185 



which readily cracks and peels off. The best varnishes are 

 made from rosin and linseed oil. Well-varnished furniture will 

 retain its good appearance for years if it is occasionally wiped 

 with a woolen rag moistened with linseed oil varnish. This is 

 also the best method of removing finger marks and grease from 

 fine furniture, such as pianos and cabinets. Locomotives and 

 exposed machines are usually coated with a varnish made by 

 dissolving pitch in turpentine ; such a varnish is durable but is 

 not desirable for furniture and indoor decorations. 



If white lead is added to varnish, the so-called white enamel 

 paints result ; and if, in addition, coloring matter is added, the 

 colored enamels result. 



Shellac is obtained by dissolving in alcohol resins obtained 

 from certain East India trees. Many different trees in East 

 India are infected by insects which puncture the bark, feed upon 

 the sap, and leave an incision through which exudes a light 

 yellow resinous matter. After sufficient of the resinous matter 

 has collected on the trees it is gathered and sold as lac. Liquid 

 shellac is a solution of lac in alcohol; it is not so durable as 

 varnish and is therefore less used. Varnish and shellac should 

 always be applied lightly and allowed to dry thoroughly. If 

 the coating is thick, it dries slowly, sticks, and finally peels off. 



Lacquer is obtained by dissolving in alcohol or turpentine 

 the sap of a small Japanese tree. 



Creosote oil for wood blocks. Railroad ties and street 

 paving blocks are protected by a cheap oil rather than by 

 paint. Wood is soaked in creosote oil until it becomes thor- 

 oughly saturated with the oily substance. The pores of the 

 wood are thus closed to the entrance of air and moisture, and 

 decay is avoided. Creosote is poisonous to insects and to many 

 animals, and thus acts as a protection against them. Wood 

 treated with creosote is very durable. Creosote oil is obtained 

 from the destructive distillation of coal and wood. 



