844 
NEW METHOD OF EFFECTING DISTILLATION. 
development of the roots, but, to illustrate the abundance in which the tuber¬ 
cles are produced, Mr. Bain has told me that he has obtained a very large quan¬ 
tity of roots from one strong plant. 
An important point to attend to is the regular carrying out of transplantation. 
The roots should be transplanted every second year, and in moving them, care 
was taken to dig very deep. Indeed, it is well to place fresh plants in fresh 
situations every year, or, if new ground cannot be had, to dig deeply round 
the old plant, and to replace the exhausted soil by new earth. 
The plant soon declines if not properly looked after, and in winter it is pru¬ 
dent to protect the roots from frost by throwing some loose rubbish or other 
material over the ground. 
Dublin, May, 1870. 
NEW METHOD OE EFFECTING DISTILLATION AND 
EVAPORATION AT HIGH TEMPERATURES. 
We have recently had an opportunity of inspecting an apparatus, fitted up by 
Messrs. Doulton and Watts, of Lambeth, for effecting distillation and evapora¬ 
tion at high temperatures, which appears to present some important advantages. 
It consists in the application of a process which was patented some time ago by 
Mr. Coffey, the pharmaceutical engineer, and in which paraffin oil, with a very 
high boiling-point, is used as a circulating medium for conveying heat from a 
furnace to the vessels in which it is to be applied. This object is generally 
attained by the use of steam, but steam at a high temperature must necessarily 
be under great pressure, and, for any temperature thus produced above 300° F., 
the pressure must be such as to entail considerable risk of explosion. With 
metallic vessels this may be provided against, but not so^with vessels of glass or 
stoneware. 
The apparatus alluded to above, and which the annexed cut illustrates, con¬ 
sists of stoneware still, pans, etc., which can be worked with perfect safety at 
any temperature up to 600° F., or even higher. In the sketch, a represents the 
furnace, which may be situated at any distance from the other parts of the appa¬ 
ratus. It consists of an enclosed fire, over which is fixed a coil of iron pipe, 
shown in section at the other end of the sketch at a. The paraffin oil is heated 
in this coil to any required temperature, -which is indicated by the pyrometer c, 
and it is thence conveyed to the jacketed pans, etc., d, e, f, g, where it can be 
turned on or off, as is usually done with steam. It circulates through the 
supply-pipes and within the jackets of the pans in a heated state, but not under 
pressure,—its boiling-point being above the temperature to which it is subjected. 
As it cools under the influence of the work done, it falls by gravitation to the 
lower range of pipes, and passes back to the furnace to be heated again. It will 
be seen that, in this method of applying heat, the difficulties that have been 
experienced in heating glass and stoneware vessels with high-pressure steam 
are entirely obviated. We believe that, in the first instance, it was found 
difficult to prevent the oil from permeating the stoneware and thus contami¬ 
nating what was contained wuthin the vessels ; but we have been assured that 
the vessels are now so well glazed that no such effect occurs. 
There are many chemical processes in which the use of this apparatus will be 
found advantageous. 
