Protection of Building Timber 577 



than a sjmilar length of heartwood cut from 

 the same tree and treated under pressure, even 

 though the process was carried so far as to 

 injure the fibres. It may fairly be advocated 

 that any timber which is immersed in an open 

 bath sufficiently to enable it to absorb approxi- 

 mately the maximum quantity of solution 

 which it is capable of taking up by capillary 

 attraction, is sufficiently impregnated for all 

 practical purposes, provided, of course, that 

 such timber is seasoned before treatment. 



"The requirements of an efficient wood pre- 

 servative in the Tropics may be summarized 

 as follows : 



"(i) It must absolutely protect the timber 

 from termites and other insects, fungus, and 

 dry rot. 



" (2) It must be easy of application, either 

 by immersion, painting, or spraying, so that 

 woodwork in situ can be treated where 

 necessary. 



" (3) It must be non-corrosive, so as not to 

 affect nails, spikes, or other metal work brought 

 into contact with it. 



"(4) It must be economical, and preferably 

 should be prepared in a highly concentrated 

 form, capable of dilution on the spot, to reduce 

 transportation charges to a minimum. 



" (5) It must not be, if possible, inflam- 

 mable ; on the contrary, it should be of such 

 a nature as to render the wood more resistive 

 to fire. 



37 



