127 
WOOD PRESERVATION AND THE PROCESS OF PRO- 
DUCING CREOSOTE OIL. 
The awakening of the American people to the dangerous de- 
struction of their forest wealth, and the necessity of a wise use 
of what remains of it is one of the most significant signs of the 
change of attitude towards the national resources. Undoubtedly, 
in the future the nation must utilize its forest crop less wastefully, 
both in the woods and in the mill, and must make provision for 
future crops; but that is not the only way to prolong the timber 
supply. If the service of the wood which is used can be length- 
ened, it will largely decrease the amount of timber which must 
be cut. And this can be done, by treating the wood with chemi- 
cals which will poison the low forms of plant life which attack 
it and cause it to decay. The growth of timber is slow, and when 
the dearth of it becomes pressing, a new crop can not be grown 
quickly enough to prevent a time of severe shortage. Preserva- 
tive treatment of timber has the advantage, as a remedy, that it 
can be applied immediately. Its importance is therefore attract- 
ing increasing attention. 
Many chemicals have been used for the preservation of timber, 
among them being blue vitrol, corrosive sublimate and chlorid of 
zinc. The most effective preservative is the substance called 
"creosote oil," or "creosote." On account of the similarity of the 
names, many people suppose this to be the creosote obtained from 
wood, such as can be obtained, refined for medicinal purposes, at 
the drug stores. But the two are quite different, and should not 
be confused. The creosote used in wood preservation is obtained 
from coal, by a most interesting process. 
Nearly every city now uses gas for light and fuel, and many 
people know that this illuminating gas is often made from coal. 
But the many things besides gas which are obtained in this process 
are not so well known. It is one of these other products from 
which is obtained the creosote oil used for wood preservation. 
To understand how all these things are produced, it is necessary 
to know something which the chemists can tell us. Coal, they 
say, is composed partly of the substance called carbon, partly of 
compounds of this carbon with the gas hydrogen, which they have 
named "hydrocarbons." When the coal is heated sufficiently, away 
from air, the hydrocarbons are driven off in the form of gas. 
Illuminating gas is made by subjecting coal of the proper kind to 
this process, which is known as "dry distillation." The coal is 
put into a long, fire-clay oven, or "retort," shaped much like a 
giant model of the little cakes which the bakers call "lady fingers," 
the retorts being about thirteen feet long, two feet wide and sixteen 
feet deep. A number of these retorts are built side by side, in 
