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 
