Oil the Preservation of Timber. 
17 
a moveable lid ; one lid was perforated for two screws, with a 
piece of iron at the end to prevent the screws penetrating the 
wood. I only used one screw, but I have shown how two or 
more screws might be added to a cylinder so as to operate upon 
more than one sleeper at a time. The other lid was cast witli an 
opening nearly corresponding in size with the end of the sleeper. 
The inside edge of this opening was cast with a ledge projecting 
about i an inch above the surface. The wood being placed in 
position, the lids were screwed on to the cylinder, and the sleeper 
forced tight against the opening in the one lid by means of the 
screws in the opposite lid. The cast-iron ledge penetrated the 
wood to the depth of h an inch, and thus prevented the liquid in 
the cylinder from escaping between the lid and end of the sleeper. 
After exposing the sleeper to the action of the liquid under less 
than the ordinary pressure, a fine mist gradually appeared over 
the whole surface of the open end, showing how complete had 
been the penetration. An examination of the interior of different 
sleepers proved that this mode of operating was most effectual, 
and much more rapid than that by the old method. After I had 
this plan in operation for some time, I discovered that M. 
Boucherie had anticipated us in one of his recent patents. 
In order to avoid any prepossession in favour of any particular 
preservative liquid, I was careful not to read any of the specifica- 
tions until the experiments were completed, and I now give an 
outline of the various materials employed, until I adopted that 
substance which will form the basis of my recommendation at 
the conclusion of this Report. 
It will be noticed that I have tried some of the materials in the 
simple form as generally adopted, and converted others into a 
solid state by subsequent decomposition as recommended by 
Payne and others. 
JMaterials employed. — I first employed dead oil or creosote 
alone, and subsequently diluted with varying proportions of water ; 
also Avood tar heated to the boiling point of water, &c. 
I then used chloride of lead in solution, and afterwards dried 
several of the sleepers at a low heat. One or more of these 
sleepers were submitted to the action of one of the following 
solutions, viz. : — 
Lime water. 
Sulphuretted hydrogen, 
Weak sulphuric acid, 
Arsenious acid. 
The next batch of sleepers were treated with lime water, and 
some of these sleepers were submitted to the following chemical 
compounds in solution, viz. : — 
VOL. XX. C 
