176 



had they not been able to close their burrows against the gas. This is one ol the major 

 premises overlooked by the promoters of chlorine extermination of marine borers. 



There remains a possibility that a practically continuous maintenance of small 

 concentrations of chlorine might prevent settling of the lar\ae on the piling; or that 

 the young teredo larvae might be more sensitive to the action of the chlorine than 

 are the adults. The results of our experiments indicate, ho\ve\er, the imjirobability 

 that chlorine (entirely aside from its many objectionable features) could economically 

 be maintained around piles in sufficient concentration for a sufficient length of time 

 to kill the borers when once established, or to be of any practical value in the pro- 

 tection of marine piling. 



SUMMARY OF CONCLUSIONS 



The following is a brief summary of the conclusions reached in the preceding 

 paper: 



1st. That straight-run or whole creosotes penetrate wood in an unaltered con- 

 dition; that is, that there is no tendency toward filtration of the heavier constituents 

 in the outer layers of the wood. 



2nd. That there is no fixation of creosote constituents in the wood, and that low 

 boiling substances do not polymerize to any appreciable extent to form high boiling 

 substances. 



3rd. That the loss of creosote from treated wood is due to the combined vola- 

 tility and solubility of the constituents in the low boiling fractions, and that the loss 

 falls almost entirely on these low boiling constituents. 



4th. That creosote constituents boiling below 235° C, while in general more 

 effective as long as they remain in the wood, are largely lost from untreated wood 

 within two or three years, therefore that the percentage of these low boiling constit- 

 uents in the oil should be limited to the amount necessary for good penetration; 

 also that the tar acid specification should refer to the fractions above 235° C* 



5th. That certain oil tar distillates have a greater protective value against 

 marine borers than that with which they have ordinarily been credited. 



6th. That inorganic substances, by themselves, have little prospect of value in 

 the preservation of marine piling against borer attack. 



7th. That chlorine treatment has no practical value in the protection of piling 

 against marine borers. 



*The commonly available whole oils, as tested by this Committee, do not contain an excessive 

 amount of light oils, from this point of view. The creosote specifications approved b\- the Committee 

 (p. 108) provide sufficient light oils for this purpose; and whole oils meeting these requirements are 

 available, as shown by the numerous tests of the Committee. 



