xv, 4 Oshima: Formosan Termites 375 



THE RELATIVE EFFECTIVENESS OF PREVENTIVES 



In order to prevent the damage caused by termites, a con- 

 siderable number of wood preservatives has been invented and 

 some of them are largely used in the Tropics. Although it 

 has been proved that camphor green oil is entirely satisfactory 

 in preventing attack by Formosan termites, it has been thought 

 desirable to determine the effectiveness of other chemicals. For 

 this purpose the following ten preservatives, which are among 

 the commonest in the market, were selected for experiments 

 that were carried on at Tainan, Formosa. 



Atlas Preservative A. — This is a mixture of arsenic and so- 

 dium hydroxide. Various chemicals containing arsenic are 

 largely used in the Tropics for exterminating termites. 



Table XXXIV. — Chemical composition of Atlas Preservative A. 



Per cent. 



Sodium hydroxide 42.20 



Arsenic 2.39 



Water 55.41 



Wood-pi-eservative A. — Manufactured by Nippon Paint and 

 Asphalt Co. Ltd. The principal ingredient of this chemical is 

 tobacco extract. It is made in the following way: Tobacco 

 leaves are boiled in a dilute aqueous solution of hydrochloric- 

 acid; the solution is filtrated, and a proper amount of sodium 

 salicylide and a solution of resin soap are added to the nitrate. 



Woodilin. — Imported from the United States. This is a mix- 

 ture of petroleum heavy oil and wood tar. 



Table XXXV. — Characteristics of woodilin. 



Color 



Dark brown, with fluorescence. 



Specific gravity (at 28 °C.) 



0.920 



Flashing point (°C.) 



51 



Fractional distillation: 



Per cent. 



110 to 150 



0.50 



150 to 210 



1.50 



210 to 240 



7.50 



240 to 270 



10.25 



270 to 300 



12.75 



Above 300 



64.00 



Residue (weight) 



4.88 



Woodol. — Manufactured by Ochiai & Co., in Tokyo. The 

 principal ingredient of this preservative is wood tar. 



