204 TREE WOUNDS AND DISEASES 



for four years at least ; but in the case of ex- 

 tensive wounds that take a long period to heal 

 over, painting may be necessary every third 

 year, in order that surface cracks may be kept 

 filled up, to prevent ingress of water. 



Creosote owes its efficacy to the fact that it is 

 one of the most virulent of plant poisons, and 

 wounds painted with the substance are com- 

 pletely protected against the attacks of insects 

 or decay-inducing organisms such as fungi. 

 For painting wounds or the insides of hollow 

 branches and trunks, previous to stopping or 

 filling, it is preferable to tar, owing to its 

 deodorising and disinfecting properties. As a 

 protection against damp creosote is, however, 

 inferior to coal-tar. 



Carbolineum is, perhaps, of more value than 

 creosote for rendering wood proof against 

 insect and fungus attacks, and like that sub- 

 stance is inferior to tar for keeping out damp. 

 Other substances, such as sulphate of copper, 

 corrosive sublimate, and zinc chloride, are 

 of value for painting wood, but are more 

 commonly in use throughout Canada and the 

 United States than in this country. 



