180 ELEMENTARY FORESTRY. 



Antiseptics. The impregnating of timber with sulphate of 

 copper (blue stone), sulphate of iron (green copperas), chloride 

 of zinc, creosote, salts of mercury, or other similar material, has 

 the effect, when properly done, of greatly increasing its dura- 

 bility. Such antiseptic substances have the power of destroying 

 the rot-producing fungi. The materials are often applied to fresh 

 logs. If dry timber is to be treated, it is first boiled or steamed 

 to open the cells. A hollow cap connected with a force pump 

 is placed over one end, and the liquid forced through the cap into 

 the wood, which results in forcing out the sap at the opposite 

 end and replacing it with the antiseptic, but the more common 

 method is that described below as the treatment given in im- 

 pregnating railroad ties in Europe. All the antiseptics mentioned 

 have been used to some extent for this purpose, but for various 

 reasons chloride of zinc is now most generally used. Railroad 

 longer than those not so treated. Impregnation also to some 

 extent renders wood fire-proof. 



Iron Railroad Ties. A few years ago it was thought prob- 

 able that iron railroad ties would come into general use in 

 Europe, owing to the scarcity of Oak ties. They have, however, 

 been found to give a very unyielding road bed, and are not gen- 

 erally liked, and are seldom used for more than a short distance 

 at railroad stations. The disposition now is to substitute impreg- 

 nated Beech ties for iron, and the successful impregnation of this 

 wood, causing it to become quite durable, has had a large effect 

 in doing away with iron ties. 



The Impregnation of Beech Wood for railway ties is a 

 large industry in Europe. Without impregnation Beech is one 

 of the least durable of woods) but by modern impregnation meth- 

 ods it can be made to last at least fifteen years in any soil, and it 

 is customary for concerns engaged in this business to warrant the 

 durability of their impregnated ties for twelve years. Pine and 

 Oak ties are not impregnated. 



The process commonly followed in many parts of Germany 

 is about as follows: A large boiler-like tank is provided, which 

 is about six feet in diameter and forty to one hundred feet long. 

 This is made with heads that can be securely and tightly bolted 

 on. It also has a small track for the cars which carry the ties. 

 Before treatment the ties are mortised to receive the rail plates. 

 After the tank is filled with cars loaded with ties the steam is 



