On the Preservation of Timber, 
21 
increased at the expense of the liquid and solid products. In 
fact, advantage is taken of this circumstance at Munich and other 
towns on the Continent, which are lighted by wood gas. 
Tar. — The tar obtained from these distillations amounted to 
about 10 per cent, on an average, and the crude pjroligneous 
acid measured from 4 to 5 gallons per cwt. of timber. 
The tar obtained by slow distillation is sufficiently fluid at 
110^ Fahrenheit to be employed at once as a preservative 
material, but its fluidity is increased, as well as its preservative 
power, by the addition of the red liquor as detailed above in the 
specification. 
Pyroligneous Acid. — The pyroligneous acid, which contains so 
much creosote, and has so long been known for its remarkable 
antiseptic power, may be neutralized by lime, and then worked 
up with the prepared tar. By this treatment each cwt. of wood 
will produce upwards of 5 gallons of a mobile and highly pre- 
servative liquid. 
I have tried this liquid at Gateshead with several sleepers 
with great success, and I have kept some by me, for several 
months, without its losing its homogeneit}'. 
Ckarcoal. — The charcoal left behind is of excellent quality, 
not, of course, so hard as that obtained from sound timber ; but 
when it is borne in mind that the principal seat of the decay in 
sleepers is really that portion under the chair, the proportion of 
hard charcoal is very large. 
Application of Products. — The purposes for which charcoal 
is used are so well known that I need not call attention to 
them ; but there is one which I must not overlook. The con- 
version of the external surface of the rails and other iron on the 
line into steel has become one of the necessities of the railway 
system, and in this process there is a large consumption of char- 
coal. As soon as the application of this process becomes general, 
the demand for charcoal, an article of such limited production in 
this country, must necessarily soon very materially enhance its 
price ; but, by the conversion of the waste sleepers, as already 
described, this contingency is, as it were, more than anticipated. 
DlFFEEENX'E IN THE OLD CKEOSOTED SlEEPEES. — The above 
observations all have reference to sleepers which have not been 
creosoted ; but, with sleepers which have been treated with dead 
oil, I find this valuable fact — that, on distilling them, nearly the 
whole of the creosote oil is recovered, in addition to that pro- 
duced by the destruction of the ligneous fibre, while the charcoal 
left behind is much more dense and hard. In some cases I have 
obtained as much as 18 per cent, of tar of a very fluid character. 
The use of the soda in preparing the tar for creosoting, while 
