PROTECTING WOODS AGAINST TERMITES. 



15 



Certain of the woods named would make very suitable veneers to 

 overlay and conceal chemically treated interior and hidden parts 

 of furniture, which could be made of any of the cheaper woods of 

 the United States. Impregnating with zinc chlorid or steeping with 

 bichlorid of mercury would be a suitable treatment of the cores 

 or interiors, after which the resistant woods could be glued upon 

 them. The ^extremely poisonous character of mercuric chlorid ren- 

 ders its use dangerous. It is sloioly volatile and there is a possibility 

 that it toill be given off continuously in small quantities from the 

 treated wood. This matter should be carefully considered in case 

 mercuric chlorid treatment is used for furniture and other house- 

 hold articles made from Kyanized wood. Coatings with heavy ivhite 

 lead paint might prove a safeguard. 



POISONS FOR WOOD-PULP PRODUCTS. 



In the tests of insecticides for wood-pulp products, white arsenic, 

 sodium arsenate, bichlorid of mercury, zinc chlorid, phenol (carbolic 

 acid), copper sulphate, antimony, sodium fluorid, and creosotes were 

 tested. The wood-pulp products in the test were various processed 

 boards used in interior finish and as substitutes for lath, tiling, etc. 



Where the board was made of four plies of fiber laminated with 

 silicate of soda, some samples were treated on each ply before lami- 

 nation, while others were treated only on the surface. These tests 

 were made in the Tropics in cooperation with American manufac- 

 turers. For the money invested, crude carbolic acid and creosotes 

 gave the best results, though the odor is a disadvantage. A summary 

 of the results is given in Table 6. 



Canvas finished by the cupra-ammonium process is not attacked by 

 termites. This process consists in subjecting the fabric to the action 

 of a solution of copper hydroxid in ammonia, whereby a compound 

 of copper and cellulose is formed on the surface in addition to some 

 change in the physical character of the fabric due to partial solution 

 and reprecipitation of the cellulose. The treatment is readily re- 

 moved by acids and other solvents for copper oxid and fades grad- 

 ually on exposure to the weather. It has never been determined in 

 the Bureau of Chemistry whether this fading is due to actual loss 

 of copper or whether it is due to chemical change. 



Table 6. — Results of tests of wood-pulp products treated witli poison to prevent 



attack by termites. 



Treatment. 



Amount 



per 

 square 

 foot. 



Amount per 



1,000 square 



feet. 



Cost per 



1,000 



square 



feet. 



Condition of sample after attack of 

 white ants. 



Untreated. 



Zinc chlorid in plies 



Zinc chlorid on surface. 



Crude carbolic acid 



Painted 2 coats both sides. 



Ounces. 

 None. 



None 



fill pounds.. 



\22i pounds.. 



7 pounds 



3 pounds 



10 gallons... 



6 gallons 



1 gallon 



$1.01 



.31 



.14 



3.50 



2.10 



.35 



Badly attacked; eaten through to sili- 

 cate. 

 fBadly attacked but not eaten through 

 \ to silicate. 



Very slightly attacked. 



Slightly attacked. 



Unattacked. 



Do. 

 Slightly attacked. 



