effect in causing or preventing stoppage in the ascension pipes there
can be no doubt; and it is important that this subject should be
thoroughly investigated.

It is of interest to consider what must be the physical condition of
the gas at these high temperatures. All the hydrocarbons which are
afterward condensed must then be in the condition of gases having
various degrees of condensability, mixed with and rendered visible by
a cloud of carbon particles or soot. If this soot could be removed
from the gas at this stage without reducing the temperature, we should
probably have no thick tar or pitch, but only comparatively
light-colored oils; and it might possibly lead to an entirely
different mode of conducting the process of condensation.

These are a few of the subjects on which it is extremely desirable
that we should possess that complete information which can only be
obtained by well-directed investigations with different materials and
under varying conditions. There are many others in connection with
carbonization and purification which might be mentioned; but I think I
have said sufficient to show the necessity that exists for more minute
investigation and research. Investigations such as are here indicated
do not involve any large expenditure of money; but they do require
care and intelligence to prevent errors being made. Experiments should
not be condemned as defective because the results differ from
old-established theories; yet when this does happen, it is in all
cases better to suspect the new experiment rather than the old theory,
until the results have been fully established.--_Wm. Foulis, Journal
of Gas Lighting._

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