A LABORATORY EVALUATION OF WOOD PRESERVATIVES 199 



equipment necessary consists of a straight-sided screw-capped bottle 

 about 5 inches high and 2 inches in diameter, a smaller bottle 2.5 

 inches high and 1 inch in diameter, a wad of cotton, a small flat piece 

 of untreated wood and an applicator such as is used by the medical 

 profession for swabs (Fig. 3). 



The treated blocks, previously brought to moisture equilibrium, are 

 supported by means of a thin slab of untreated wood on the top of 

 the small bottle which is placed inside the larger screw-topped bottle. 



Fig. 4 — Assembly of apparatus required for modified wood-block method of assay. 



Through holes bored in the test piece and the thin slab of supporting 

 wood are passed the pieces of wooden applicator, which act as a 

 means of anchorage and as wicks for conduction of water to the wood 

 under test. Although not absolutely necessary, cotton is usually 

 wrapped around the small bottle to reduce shock during handling. 

 Water is placed in both bottles and after sterilization of the complete 

 set-up (Fig. 4) the thin slab of wood is inoculated with a portion of 



