fore carried out with w^ter leaching at a temperature of 80°C, The results 

 were similar to those in Virhich boiling seav/ater was used. 



In a later series of experiments a leaching bath was used in v/hich fresh 

 water T>ras maintained at 80°C. with a constant rate of inflow and outflow 

 in order to remove the leached materials. Seven groups of l/8 inch wooden 

 slips treated with creosote to retention of from 2 to 30 lbs. /cubic foot 

 were prepared for this experiment at the Naval Research Laboratory. In each 

 group panels were leached for periods varying from to I48 days, and sub- 

 sequently exposed to attack in the sea for a period of six months. The 

 results are shown in Table 3. It will be noted that the borer resistance 

 of the treatments decreases progressively with the duration of leaching. 



From the data of Table 3, it is clear that a low retention creosote treat- 

 ment requires less leaching to reduce its anti-borer effectiveness to a 

 predetermined degree than does a high retention treatment. There is thus 

 a definite possibility that the period of leaching required to do this may 

 be used as a rough index of the effective life of the treatment. In order 

 to test this over a long period and for purposes of comparison and cali- 

 bration, larger (2" x h") timbers lare being exposed to borer attack at the 

 same location at Miami Beach. 



From data similar to that of Table 3j leaching ratings., were derived 

 for various degrees of creosote retention. The ratings (Table h) are in 

 terms of the minimum leaching period required to cause light borer attack 

 when subsequently exposed to a 3-monthil field exposure. 



As an illustration of the possible uses of the leaching test, an assay was 

 made' of preservatives developed by the Dow Chemical Com.pany, with the kind 

 permission of Dr. Fred J. Myers. The data are reproduced here in Tables 

 S and 6, Table 5 records the results of a leaching test carried out upon 

 seven preservative treatments in a manner similar to that used for the 

 creosote treatments recorded in Table 3. % comparing the data of Table $ 

 i7ith the "leaching ratings" for the creosote panels, it is possible to 

 rate the Dow treatments in terms of equivalent creosote retentions (Table 

 6). According to this system of evaluation, the Dow treatment /v? is some- 

 what superior in service life and effectiveness to a 30 lb, creosote 

 treatment, while r/'5 and #6 approximate more closely to 20 lb, (l5-30) creo- 

 sote treatment. 



It is not yet possible to make any claims for the accelerated leaching test 

 as an index of service life. On the other hand, the experiments conducted 

 so far suggest interesting possibilities and they are therefore being con- 

 tinued in the hope of developing a standard test protocol v/hich vdll serve 

 to evaluate the probable effectiveness and length of service life of chemi - 

 cal wood borer preventives. 



Should such a test method be developed, proven, and calibrated, it should 

 enormously shorten the time needed to evaluate experiiaental treatments. It 

 should also be of great value in the difficult task of isolating the effec- 

 tive ingredient or ingredients in creosote. 



J - k 



