12 BULLETIN 1231, U. S. DEPARTMENT OF AGRICULTURE. 



Table 5. — Results of tests of methods of impregnating woods, etc. — Continued. 



Treatment. 



Results. 



Open-tank process, using yellow pine for test— Continued. 



Boiled 1^ hours in a stock solution of poisoned kerosene emulsion (1 gallon water, 

 2 gallons kerosene oil, V pound naphtha soap, A- pound sodium arsenate) — 

 Allowed to cool in mixture " 



Cooled and dipped in carbolineum 



Boiled 1 hour in 2 gallons of creosote emulsion poisoned with \ pound sodium 

 arsenate — 



Allowed to cool in the mixture 



Left in kerosene oil for 1 hour after treatment 



Left in coal-tar creosote for 1 hour after treatment 



Boiled 1 hour in 1 gallon kerosene oil, 1 gallon coal-tar creosote, h pound naphtha 

 soap, J pound sodium arsenate, 1 gallon water; allowed to stand 1 hour in car- 

 bolineum. 

 Boiled A hour in a 5 per cent solution of sodium arsenate and left soaking for 2 

 days, then boiled for 1 hour in sodium arsenate and soaked for 1 hour in car- 

 boiineum. 

 Boiling: 



Paraffin wax, tested with both coniferous and hardwood species 



Saccharine solution and arsenic, tested with maple and ash 



Chlorinated naphthalene, tested with both coniferous and hardwood species 



Impregnation and baking: 



Formaldehyde and carbolic acid combination, tested with pine 



Encysting: 



Naphthalene, paraffin, and silica, tested with ash 



Failure after 

 years. 

 Do. 



Do. 

 Do. 



Do. 



Not attacked by 

 termites after 6 

 years' test. 

 Do. 



Failure after 6 



months. 

 Failure after 1A; 



years. 

 Not attacked after 



3 years. 



Failure after S 

 years. 



Failure after 7 

 years (sweat 

 badly). 



OTHER TREATMENTS. 



There are also simpler though less effective methods other than 

 treatment with chemicals to prolong the life of timber, such as set- 

 ting in stone, charring, steaming (PL I, fig. 2) , etc. By burning (i. e., 

 for poles, posts, etc.) in an open fire till the outer layers are charred, 

 wood is rendered more resistant to insect attack. Charred wood will 

 not be damaged by termites till one year after being set in the ground, 

 and not seriously damaged till after at least two years of service. 

 However, charring should not be depended upon to preserve wood, 

 although it is quite possible that it renders the wood more resistant 

 to insect attack. A more effective method is to dip the butts of fence 

 posts for a few minutes in crude oil and then char them. 



TREATMENTS FOR WOOD PRODUCTS NOT TO BE SET IN CONTACT 

 WITH THE GROUND OR IN WET SITUATIONS. 



Finishing products — such as cabinet woods, furniture, and the in- 

 terior woodwork in buildings — as well as unfinished products stored 

 to season before finishing, require treatment different from that given 

 to crude products to be set in the ground. While the preservatives 

 with which such woods are to be treated should generally be anti- 

 septic, they should never be insoluble in water, except in the case of 

 flooring or other woods near or in contact with the ground. These 

 preservatives in most cases should not " sweat out " or stain the wood. 

 Impregnation with 2 to 5 per cent solutions of zinc chlorid by the 

 Bethel full-cell process or " Burnettizing " is in most common prac- 

 tice; only the woods which treat with the greatest difficulty require 

 6 per cent solutions. 



