船底塗料に對するD.D.T.の應用
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概要
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Dichloro-Diphenyl-Trichloroethane is commonly called D.D.T. and it is a well known fact that its catalytic action has poisonous effect on insects. With the presumption that the same effect may be seen on barnacles and seroula of algae, a soaking test has been performed with a test paint which has been mixed with D.D.T. to experiment of its utility value as shipbottom paint. The first water test experiment was conducted on July 1947 at the quay in Yokohama Harbor by ship-bottom paint number one and finishing it with paint containing 10% D.D.T. Kerosene Solution (as D.D.T. 0.5%). The result of the experiment showed that D.D.T. has some effect on barnacles during its breeding months of Summer. However, Since it was impossible to increase the compound ratio of the above percentage we were unable to obtain the final result. The second test was performed in the Autumn of the same year, when seroula is plentiful, by increasing the mixture of kerosene solution from 5% to 40% with paint (as D.D.T. from 0.25% to 2.0%). But the result was not too favorable when compared to the test on barnacles. However, we learned that with the increase of D.D.T. contents it gradually became effective. A similar test was further continued the following year with a 1% mixture of pure D.D.T. crystal, on a part of the bottom of the tug boat which runs within Yokohama Harbor. As a result of this test, it proved to verify our previous experiments that D.D.T. is very promising as poison to be used in shipbottom paint. (1) The effect that D.D.T. has on barnacles is very promising and with a 10% mixture of D.D.T. it will completely stop the growth of barnacles for a long time. It can be recommended as a substitute for the heretofore used mercury commpound. (2) D.D.T. has considerable effect on serpula but not quite so effective when compared to barnacles. (3) The same could be said of in reference to "kokemushi" (Phylum molluscoidea-Class Bryozoa Gymuo, aemats). (4) D.D.T. alone will not serve a poison when used along with shipbottom paint. It is ideal to mix with inorganic poisonous matters such as copper compound which is effective to serpula and algae.