Part II.] Pearson : Antiseptic Treatment of Timber . 
17 
Chapter II. 
Process of Injection by Hydrostatic or Pneumatic 
Agency. 
(X) CREOSOTINQ. 
Creosoting. 
Creosoting is carried out by forcing the oil into the timber under 
pressure. It is one of the oldest methods of preserving timber employed 
in Europe and America and still to a great extent holds the field against 
other more recent inventions. 
The process is briefly as follows : — 
The converted timber to be treated is placed in iron cylinders to 
which is connected both a vacuum and pressure pump. 
When the work is carried out on a large scale the sawn 
material is packed on trucks, which, running on rails, are 
moved into the cylinders, and the rails removed when the 
retort has been filled, to allow the air-tight door being 
closed. The older method was then to subject the wood to 
a process of steaming which lasted about an hour, but this is 
now generally not carried out ; instead, the timber is subjected 
to artificial drying in hot air chambers lasting 24 hours 
or more, before being treated with creosote. The process of 
artificial drying has to be carried out with care, as either 
heating to a temperature much over boiling point or 
prolonging the drying for too long a period is injurious to 
the timber. When the converted material has been arti¬ 
ficially dried and put into the retorts a vacuum is created 
by means of the pump connected with the cylinder and what 
moisture may remain in the timber is extracted. The 
creosote is then forced into the retort by a pressure pump, 
at. a temperature of 60° C to 70° C and kept at a pressure of 
( 90 ) 
c 
