480 



THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



Other things being equal, one can then consider and plan for treatment 

 retentions sufficiently high to assure a protective residual of a given 

 preservative for a long, economical service life of the treated plant units. 

 This service life is not necessarily an indefinitely long life, nor is it the 

 maximum physical life that might be obtained by using relatively larger 

 quantities of preservatives than might be consistent with cleanliness 

 requirements. Implicit is the idea of avoiding at all times heavy main- 

 tenance and replacement costs on account of decay, but particularly in 

 the early life of the line. To accomplish these ends it. is necessary to know 

 how much preservative to use. 



The following interpretation of the results of soil-block tests is con- 

 fined to weathered block experiments, for the practical reasons previ- 

 ously cited. The interpretation is not offered as something entirely new; 

 but it looks like a good working hypothesis, and it seems to help in 

 explaining what may be happening in laboratory soil-block tests of 

 creosote. 



Table XXXV — Summary and Interpretation of Soil-Block 



Tests 



Weathered, creosoted southern pine sapwood blocks; creosote losses; amounts 



* Creosotes 1, 2, 3, 6, 7, 8, 9, 10 and 11 are those in use in the Cooperative Creo- 

 sote Tests (see Bibliography, References 12 and 39). Oils 9a and 10a are samples 

 from the same lots as numbers 9 and 10. (See Bibliography, Reference 36.) For 

 oils Ml and M2 see Bibliography, References 37 and 38. Creosote 5340 is shown 

 in Table II. 



