18 
Indian Forest Records. 
[Vol. III. 
about 6 atmospheres for an hour or more. Boulton, quoted 
by Fisher, maintains that under his process, by which oil is 
forced into every fibre of the timber, sleepers are less liable 
to split owing to the temperature employed being higher 
than they are likely to be subjected to afterwards. 
After treatment the fluid is drawn out of the cylinders into the re¬ 
servoir and the trucks containing the creosoted wood removed. 
Factors governing Effective Creosoting. 
To render the process of Creosoting thorough and effective great care 
should be taken in seasoning the wood. It is most essential that it should 
he naturally well seasoned and, if necessary, further dried hy artificial 
means. 
Another most important point is the quality of the Creosote used. 
Tar is an extremely complex substance of organic compounds, varying 
according to the quality of the coal from which it is obtained, and 
further according to the way it is treated. Some tars, as for instance 
those from the Newcastle district, yield small quantities of carbolic and 
cresylic acids and contain more of those semi-solid substances which 
solidify within the pores of the timber, while others have more of those 
acids and contain a higher percentage of lighter oils, with a relatively 
low boiling point. The antiseptic properties of these acids is undisputed, 
thus a certain percentage of them in a solution is most desirable, but as 
they are not very stable, having a low boiling point and being readily 
soluble in water they cannot be relied upon for the preservation of timber 
unmixed with other substances. It is the heavy and less volatile portions 
of the Creosote oils to which one must look for the effective protection 
of the timber, in other words to those oils which have a relatively high 
boiling point, of 250° C. to 275° C. or even over. 
Experiments carried out many years ago by Boulton pointed to the 
use of oils coming over at a high temperature, and the more recent 
results published by Mr. Gellert Alleman, Professor of Chemistry, 
( 91 ) 
