WOOD SOIL CONTACT CULTURE TECHNIQUE 135 



permanence of the preservative. However, heating, leaching and other 

 simulated weathering cycles may be used in conjunction with the soil- 

 contact method to determine the stability of a preservative to evaporation, 

 to the solvent action of ground water, and to chemical deterioration by ultra- 

 violet light. Futher comparisons between soil-contact assay and field test 

 of a wood preservative such as Greensalt confirms the fact that conditions 

 for decay are more nearly optimum in the former and result in an unusually 

 severe test of the preser\'atives. 



The soil-contact method is an excellent laboratory tool easily adapted to 

 fundamental studies of the decay process and to evaluation of preservatives. 

 The method has shown considerable promise in evaluating preservatives for 

 a wide variety of materials, including leather, cotton, felt, paper and jute. 

 Since the factors influencing decay are very near optimum in the soil-contact 

 method, any preser\'ative that prevents decay in this laborator\^ test and is 

 permanently retained will be effective under any climatic conditions. 



ACKNOWLEDGIIENT 



I wish to express my appreciation to Dr. S. F. Trelease of Columbia 

 University for his help and guidance in the preparation of the manuscript 

 and to Dr. R. H. Colley and other members of the Bell Telephone Laborato- 

 ries Staff for their advice and counsel throughout the work. 



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