September 30, 1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
273 
SOCIETY OF ARTS. 
Boiled Oils and Tarnishes. 
BY CHARLES W. VINCENT, ESQ,. 
[Concluded from par/e 255.) 
Tlio jacket and pan should he capable of standing* a 
working pressure of 40 lh. per inch. The top of the 
pan is closed by a dome riveted to' it, and forming 
part of it. This dome is provided with a man-hole, 
and in the centre is furnished with a stuffing-box, I 
through which pass two shafts, one encircling the | 
other, and each hearing a fan, which fans, by gearing 
outside the pan, are made to rotate in opposite direc¬ 
tions, intersecting each other in so doing, and, as may j 
be conceived, producing a most thorough admixture of 
any solid and fluid substances submitted to their dash¬ 
ing and cutting action. At one side of the top of the 1 
dome is a kind of cupola, from the top of which issues ! 
a three-inch pipe, which is carried down to the ash-pit j 
below the boiler furnace. When at work, care is taken | 
that every joint is tight, hence any vapours arising in ( 
the interior of the pan have no chance of escaping into 
the air till they have passed the burning coals. One of 
the greatest dangers and also disagreeable nuisances 
being thus obviated, oil-boiling can be, and is carried 
on without objection on the part of either the insurance 
companies or the public at large, even in the heart of 
densely-populated districts. I myself boiled oil and 
made varnish in Milford Lane, Strand, for three years, 
without increasing the insurance of the Illustrated London 
Neivs, though I used steam from their boilers for the 
purpose. 
At the lower part of the pan, the inch-pipe from a 
powerful air force-pump penetrates through the jacket 
to the interior of the pan. 
The workman’s first care is to see that all his taps 
and valves are in good, efficient order, and turned the 
right way, after which the mode of manipulation is the 
following:— 
The linseed-oil is first shot into a large tank, holding ; 
one batch for boiling (about two tons is the usual quan¬ 
tity), and allowed to settle for four or five hours, accord¬ 
ing to the time taken for boiling the previous batch, 
matters being so arranged that as soon as one batch is 
pumped up into the pan another is shot into the tank, 
so that the oil may have as long a time for freeing itself, 
from mechanical impurities as can be spared for that 
purpose. The waste steam from the pan passes through 
a coil of inch and a half iron pipe placed in this tank, so t 
that the oil is also being warmed, tliis much facilitating j 
the separation of particles of dust, mucilage, etc., and j 
also saving time when the actual boiling commences. 
The time having arrived when the pan is ready, the oil ! 
has acquired a temperature of about 95° F. before it j 
is pmnped up (in the works I am describing the arrange- , 
ment of pumps used took about seven minutes to elevate j 
two tons of oil twenty feet), full pressure of steam is then : 
turned on the pan, and the fan started. At first there is 
little or no disagreeable smell to be perceived. If the 
man-hole of the pan be open, an observer can watch the 
oil churning round with very little frothing, although 
the blades of the two fans, rotating in opposite directions, 
cause such a perfect commingling of the oil and the ! 
air that is in the upper part of the pan, that, looking in 
upon the whole fluid mass, it seems as if the bulk were 
greatly increased, as it goes on swelling and chafing, 
with a hollow rumbling noise, at the rough treatment it 
is receiving. A few minutes later, a faint, sickly odour 
is to be perceived, something like the smell of the raw 
oil, but intensified as to its woody constituents. The 
oil is now nearly hot enough for the air to be turned I 
j on. This may bo done as soon as the steam reaches a 
pressure of 35 lbs. to the square inch on the pan. Directly 
this is done, the character and the appearance of the oil 
changes; the bulk appears to be still more increased, a 
foaming, seething, whirling vortex presents itself, tho 
colour suddenly changes from the dark brown it pre¬ 
viously exhibited to a mass of palo yellow bubbles, and 
the strong pungent odour universally accompanying the 
boiling of oil makes itself known and felt by the dis¬ 
charge from eyes and nose, if the curious observer does 
not take the hint that it is time tho man-hole was closed, 
and tho cauldron loft to complete its witchery in dark- 
ness and solitude, if not in silence. But before it is left 
j to itself, it may bo well to observe that, before the air 
j was turned on, a taper would burn in any part of tho 
! space above the oil where it was safe from being extin¬ 
guished by splashes. After tho air has been blown 
through the oil for a short time, if both the flue and air- 
pumps be stopped, so that a perfectly quiescent atmo¬ 
sphere remains above the oil, it is found to bo perfectly 
incapable of supporting combustion. A few inches in¬ 
side tho man-hole, I have found that a brown paper 
torch, dipped in turpentine, has been immediately ex¬ 
tinguished. 
If a dark boiled-oil is desired, the driers should be put 
in as soon as the oil is thoroughly heated throughout 
its bulk, which is commonly about half an hour after 
the steam has an indicated pressure of 35 lbs. They aro 
ground to a fine powder, mixed with oil, and are intro¬ 
duced through a funnel, with a stop-cock intervening 
between it and the pan, in a thin stream, so as to secure 
as perfect a distribution of them as possible throughout 
tho oil. The quantity of driers used amounts only to 
about three quarters of a pound to each hundred-weight 
of oil, so that the necessity is obvious of great pains 
being taken to secure and maintain as complete a dif¬ 
fusion through the liquid as can be attained, and thus 
coincide with the theory of this method of oil-boiling, 
which requires that each particle of oil should bo in 
contact or proximity to a particle of tho drier used and 
oxygen at one and the same time. 
Subsequent to the introduction of the driers, no atten¬ 
tion is required to the process save to see that the air- 
pump and fan are kept constantly at work, and that tho 
pressure of steam on the pan does not sink at all below 
30 lbs., 35 lbs. being that which ought to be adhered to. 
Tho right quantity of air to be introduced for the oxida¬ 
tion of a given quantity of oil has not been ascertained. 
In practice, it is found that some oils require, and will 
consume a larger amount than others ; the custom is to 
throw in as much as the oil will take without frothing 
up and priming into tho condenser. The cooling effect 
of the air thus introduced is much less than might bo 
supposed, in point of fact, the pressure to which it is 
subjected in overcoming the weight of the oil, lifting 
the heavy valves, and the friction tubes it passes through, 
considerably raises its temperature before it enters tho 
pan; it is generally found to be raised some 20 to 30 
degrees above the temperature it previously had by tho 
time it reaches the oil. Indeed, the tubes through which 
it passes not unfrequently become hotter than the bare 
hand would bo able to hold in a firm grip. In four 
hours’ time tho oil is generally fit for removing from 
the pan to a tank, where it can remain a sufficient timo 
for the major part of the driers to settle out from it. 
When bright, it is then either pumped or run off into 
other tanks for warehousing, or may be allowed to re¬ 
main where it is for the future use, if there arc plenty ot 
working tanks. 
The mode of emptying the pan is by allowing the oil 
to rush out through a two-inch tap in the centre of 
the bottom of the pan into pipes which are . connected by 
running-joints, and lead it in any desirecl direction. 
Sometimes, a little difficulty occurs in dropping the oil, 
through the orifice of the tap leading into the pan be¬ 
coming stopped up by an accumulation ot driers, or by 
