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those which do commercial treating for several railroa?s or for private 
companies. With the exception of the plants at Gaiesburg and Madison, 
these plants receive ties from the region now under discussion. 
The railroad companies have taken the lead in timber preservation 
because of the increasing scarcity and high prices of rathway ties, this 
being one class of material for which no satisfactory substitute has been 
invented. They have found that many species of timber not sufficiently 
durable for cross-ties may be made so by preservative treatment. Many 
of them have been creosoting timber long enough to obtain reliable data 
from experimental tracks laid with ties treated by various methods, upon 
which exact observations have been made through extended periods under 
all classes of climate and soil conditions. 
A number of the large steam roads, for example, the Burlington in 
Illinois, have extensive treating plants fitted to handle large quantities of 
timber in an efficient manner. Starting in with cross-ties, many have 
found out that it effects a great saving to treat every stick of timber used 
for trestles, piling, bridge-stringers, and telephone poles. They have found 
out that all species need air-seasoning for a considerable length of time 
and some of them keep as much as six million feet of material in their 
yards for a year—which means carrying a heavy investment. The idea 
seems to be growing that all species are benefited by preservative treat- 
ment and that all can be treated successfully and advantageously. 
Nearly all cross-ties are treated by the closed tank or “pressure 
process,” in which the wood is subjected to treatment under pressure 
designed to secure a heavy absorption of the preservative. There may be 
as many as eight of these treating cylinders at one plant, each about 125 
feet long and from five to six feet in diameter, with heavy air-tight doors 
which can be locked while the cylinder is being subjected to an initial 
vacuum or to pressure. Each cylinder will hold about 16 steel cars or 
“cylinder buggies,’ which after being loaded with 52 eight-foot ties, are 
drawn into the cylinders by means of cables or small donkey engines, each 
filling by these cars being known as a “charge.” The displacement of one 
of these cylinders is about 3,900 cubic feet. 
Preservatives used.—The principal preservatives in use at the present 
time are creosote oil, zine chloride, and an emulsion of zinc chloride and 
creosote, treatment with the last being known as the “Card process” from 
its inventor. Modifications of the method known as the “pressure process” 
have been devised to bring about preservation without taking too much of 
the liquid. One of these, known as the Rueping process, is used with 
creosote at the plants at Metropolis and elsewhere. Since its design is 
to leave the creosote only in the cell walls and not in the pores of the 
wood cells, it is sometimes called the “empty cell” process. 
