SPONTANEOUS IGNITION OF CHIP CAKE. 
49 
and increase of temperature, we might thence 
infer the law both of attraction and renulsion 
between the surfaces : and thence, (if the ex- 
pression be integrable,) that between the mo- 
le.cules of the substances- 
All this, as just observed, tabes place only 
within a certain range of interval. When the 
central black is formed, we seem to have ar- 
rived at a limit where attraction prevails; and 
where the application, even of great heat, will 
not easily overcome it. 
f The close contact of a glass and liquid in 
caoillary attraction appears to be within this 
limit ; for here, in several cases referred to in 
my paper, it appears that no application of 
heat can overcome the attraction. 
With respect to one of those experiments, 
viz ; that of Sig. Libri, which I had stated I 
could not succeed in repeating, I have since 
been informed that the experiment suc- 
ceed, provided the heat applied to the wire 
be that of a flame urged by a blowpipe. 
This, at any rate, proves the great intensity of 
the attraction, which requires so extremely 
high a degree of heat to overcome it. 
Oxford, Feb. 17, 18:^5. 
INSTANCES OF SPONTANEOUS COI\I- 
BUSTION. DETAILED IN A PAPER 
READ BEFORE TH E ROYA L IRISH 
ACADE.AIY. 
May, 1835. 
By M. Sca.nlan, Esq.* 
Id the beginning of last March a lire broke 
out in the extensive turpentine rlistillery on 
Sir John Rogerson’s quay, belonging to Mr. 
Jolin Fish Murphy, which is seperated from 
my chemical factory by Windmill Lane, The 
file, which was speedily got under, uas con- 
fined (o a heap of wliat is termed, by turpen- 
tine distillers, chip cake, and, from the 
circumstances under which it occurred, could 
not be attributed to any other cause than tlie 
act of an incendiary, or to the spontaneous 
ignition of this chip cake. 
As 8[)ontaueou9 combustion of this .substance 
had never occurreil before in Mr. \)iir|)hy’3 
distillery, nor in that of his father an exten- 
sive distiller of turpentine, for many years, 
at Stratford in Essex, I at first doubted that 
the fire could liave originated in this way ; 
however, on inquiry, I found his mode of 
w orking had been, on this particular occasion, 
diflerent from (hat nsuallv employed in Ins 
distillery, and, experiments wlilch he kindly 
permitted me to make have since proved 
beyond doubt that combustion did take place 
spontaneously. 
Raw turpentine, a,s it comes from America, 
in barrels, includes a considerable quantity of 
impurity, consisting of chips of wootl, leaves, 
nnd leafstalks.*]' It was hitherto the practice, 
• Communicated by the Author. 
+ The following extract from the letter of a 
French tui’pentine merchant, will account for 
the presence of these foreign bodies. To obtain 
the tui’pentina “ the fir timber is chopped about 
a man’s height down its side with an axo, not 
ill Mr. Murphy's distillery, as it is in England, 
to heat the raw turpentine up to a temperature 
of about 180'’, as I found by plunging a 
thermometer into one of his large copper 
pans, and to strain the turpentine, thus liqui- 
fied, from the impurities, previously to intro- 
ducing it into the still, where it is submitted 
to distillation in the usual way, with a portion 
of a water, yielding turpentine oil, which 
(li-stills over a’ong witli the water and rosin 
which remains behind in the stld. The chips, 
when separated by a wire strainer, still retain 
a quantity of adhering turiientine worth saving, 
and with this view are transferred to a largo 
close vat, where they are exposed for some 
time to the action of steam furnished by a 
boiier kept for this purpose, as well as for 
steaming the empty barrels, in order to remove 
any turpentine that may adhere to them. 
Still, however, tiie chips are a good deal 
imbued with resinous Jnatter. and in this state 
form a loose })orous mass, which the turpen- 
tine distillers call chip cake, a material which 
is used by the poor in the neighbourhood aa 
fuel. 
As long as the process T iiave just described 
was pursued, which is the London mode, and 
that which produces the best rosin, no accident 
occurred frntn fire in iVlr. Murphy’s premise.s, 
although I have rrequently seen immen.se 
heaps of tliis chip cake collected together in 
his yard; but, on making trial of a different 
plan, namely, that fuactised by a Dublin 
(listiber. Mr. Price of Lincoln Lane, the 
accident in question occurred. 
On this occa.sion, the raw turpentine, 
together with its impurities, was put directly 
into the still, along w'ith the proper quantity of 
water, and the boiling rosin at the end of the 
operation strained from the chips. 
The chip cake resulting from a single opera- 
tion thus conducted was laid in a heap outside 
tlie still lioiise, at three o’clock in the after- 
noon, and at midnight was observed to be in 
tlames. 
In the first mentioned process it is obviona 
the chips ivere never exposed to a higher 
degree of temperature than 212^ ; but in the 
latter, especially when it is the object of the 
mauiifacturer to make amber rosin, the 
temperature to which they are expo-sed sa 
much higher. 
The first experiment I made was on the l6'h 
Biarch. I found (he temperature of the boiling 
rosin, in the still, to be 2530 when the turpen- 
tine oil and water bad been distilled off, the 
fi e just drawn frorn under the still, nnd when 
the liquid losin was in the net of being 
sirained from the chips which were introduced 
into the still with the tiir^ientine. 
I haii the whole of the chip cake resulting 
from this distillation carried into my own 
)ard, upon a wire screen, and left in the open 
air, with a view of watching its progress. 
hand deep and afterwards higher up. The tur - 
pontine or pat is scraped up from the 
foot of the tree. That which is on the side 
wound, when scrapea oft', is white, and called 
galley pat, of which the burning incense is 
made, it does not yield so much turpentine 
spirit as the pat ," — Euit, 
