NAPHTHALINING. 307 



heated naphthaline, a solid coal-tar product, a process originally 

 introduced in 1882, has recently come into extensive use for 

 estate purposes (fence-posts and stobs) under an improved 

 method, which makes wood like Birch, Beech, Scots Pine, 

 Spruce, &c., more durable than untreated Oak or Larch, and 

 thus giving fencing material that is both cheaper and lasts 

 longer (up to 15 to 20 years). 



In naphthalining, the crude naphthaline is brought in bags 

 and put into an iron tank heated by steam from a boiler about 



20 yards off, the stove for heating the boiler being carefully 

 isolated owing to the inflammability of the naphthaline. The 

 wood to be treated must be thoroughly seasoned ; and the drier 

 it is, the better the impregnation. The tank being packed with 

 fence-posts and stobs and then nearly filled with crude naph- 

 thaline (which melts at 176, and boils at 422 Fahr.), steam is 

 applied to raise the heat to over the boiling-point of water 

 (212). After being kept at this for from two to twelve hours, 

 it is allowed to cool down sufficiently for the wood to be taken 

 out ; then other wood and more naphthaline are put in, and the 

 process repeated till all the material has been treated. A tank 



21 ft. long and 5 ft. diameter costs about .120, and contains a 

 charge of about 2 tons of naphthaline along with the wood ; 

 and when the crude naphthaline costs 35s. a ton at a railway 

 station not far off, the impregnation of tank-loads of mixed 

 hardwoods and softwoods averages about 3d. per cubic foot. 

 The power of absorbing naphthaline is greatest in Scots Pine, 

 Beech, Birch, Alder, and Douglas Fir ; much less in Ash, Silver 

 Fir, and Oak ; and least of all in Spruce, Larch, and Elm. But 

 creosoting is the preferable method, as naphthalining gives the 

 workmen headaches, is apt to make them feel giddy, and is 

 altogether a more dangerous process. 



Powell's saccharisation process is a recent British method 

 for impregnating the woody tissue with molasses, glucose, or 

 sugar. It darkens the colour of wood, and is said to increase 



