IMPROVING THE QUALITY OF WOOD. 505 



cracks. Solutions of lac or of Manilla copal in alcohol are 

 rubbed on the wood. Oak parquet floors are rubbed with 

 beeswax to make them shine. Lacquering is used for inferior 

 furniture, by rubbing it with solutions of copal, sandarac, 

 mastic in alcohol or turpentine ; or with that of copal in 

 linseed oil, this dries slowly but affords the most permanent 

 lacquer. Japanese lacquering, famed for its durability, is 

 effected by means of the latex of nhns rernidjern. Woods of 

 Chamaecyparis and Ma</ii<>Ua are the substrata of the best 

 Japanese lacquered work. Cryptomrriii wood is used chiefly 

 for inferior goods that are exported to Europe or America. 



4. Improvement in Hardness. 



This may be effected either by hardening or by first 

 softening the wood. The fibres of the wood are softened by 

 boiling the wood in water, or better by steaming it under 

 pressure ; if before steaming it, the wood (e.g. beech wood) 

 is steeped in dilute hydrochloric acid, it becomes, after being 

 steamed, so soft and plastic that it can be pressed into -J-th of 

 its original volume. Boiling wood in saturated solutions of 

 calcium-chloride also renders it soft and plastic. Wood 

 may be hardened if it is painted with soluble- glass, or better 

 still, if it is impregnated with soluble-glass by pneumatic 

 pressure. Impregnation of wood with caustic potash or soda 

 renders it highly resistant to atmospheric influences. 



5. Increasing the Weight of Wood. 



If increasing the weight of wood could improve its economic 

 value, it would be quite easy to effect this, but whenever the 

 weight and durability of wood is increased by impregnating 

 it, the extra weight is an accompaniment that is burden- 

 some in commerce, so that there can be no advantage in 

 increasing the weight of the wood unless some other advantage 

 is secured. A reduction in the weight of wood is attainable 

 and advantageous only as long as it contains water. Once 

 wood is dry, its weight can be reduced only by destroying its 

 substance. Hence, where lightness is desirable, softwood 

 instead of hardwood should be chosen, or the lightest oak- 



