INFLAMMATION. 
38 
chief commandant was immediately informed by an offi¬ 
cer ; he came with all poffible fpeed, and through a fmall 
hole in the door faw the mat fmoking. Without open¬ 
ing the door, he difpatched a meffenger to the members of 
the commiffion; but, as the fmoke became ftronger, and 
fire began to appear, the commandant found it necelfary, 
without waiting for the members of the commiffion, to 
break the feals and open the door. No fooner was the 
air thus admitted, than the mat began to burn with 
greater force, and prefently it burft into a flame. 
The Ruffian admiralty, being now fully convinced of 
the feif-enkindling property of the compofition, tranf- 
mitted their experiment to the Imperial Academy of Sci¬ 
ences; who appointed Mr. Georgi, a very learned and 
able adjunft of the academy, to make farther experiments 
on the fubjeft. Previous to the relation of thefe experi¬ 
ments, it is neceflary to obferve, that the Ruffian fir- 
black is three or four times more heavy, thick,' and unftu- 
ous, than that kind of painters’ black which the Germans 
call kien-rahm. The former is gathered atOchta, near St. 
Peterlburgh, at Mofcow, at Archangel, and other places, 
in little wooden huts, from refinous fir-wood, and the 
unftuous bark of birch, by means of an apparatus uncom¬ 
monly Ample, confifting of pots without bottoms fet one 
upon the other ; and is fold very cheap. The famous fine 
German kien-rahm is called in Ruffia Holland's black. In 
what follows, when raw oil is fpoken of, it is to be un- 
derftood of linfeed-oil or hemp-oil; but mod commonly 
the latter. The varniffi is made of five pounds of hemp- 
oil boiled with two ounces and a half of minium. For 
wrapping up the compofition, Mr. Georgi made ufe of 
coarle hemp-linen, and always fingle, never double. The 
impregnations and mixtures were made in a large wooden 
bowl, in which they flood open till they were wrapped up 
in linen. 
Three pounds of Ruffian fir-black were flovvly impreg¬ 
nated with five pounds of hemp-oil varniffi ; and, when 
the mixture had flood open five hours, it was bound up 
in linen. By this, procefs it became clotted ; but fome of 
the black remained dry. When the bundle had lain fix- 
teen hours in a cheft, it was obferved to emit a very nau- 
fieous, and rather putrid, finell, not quite unlike that of 
boiling oil. Some parts of it became warm, and (learned 
much ; this fleam was watery, and by no means in¬ 
flammable. Eighteen hours after the mixture was wrap¬ 
ped up, one place became brown, emitted fmoke, and di- 
reftly afterwards glowing fire appeared. The fame thing 
happened in a fecond and a third place, though other places 
were fcarcely warm. The fire crept (lowly around, and 
gave a thick, grey, (linking, fmoke. Mr. Georgi took the 
bundle out of the cheft, and laid it on a (tone pavement; 
•when, on being expofed to the free air, there arofe a flow 
burning flame, a fpan high, with a ftrong body of fmoke. 
Not long afterwards there appeared, here and there, feve- 
xal chaps or clefts, as from a little volcano, the vapour if- 
fuing from which burft into flame. On his breaking the 
lump, it burft into a very violent flame, full three feet 
high, which foon grew lefs, and then went out. The 
lmoking and glowing fire lafted for the fpace of fix hours; 
and afterwards the remainder continued to glow without 
fmoke for two hours longer. The grey earthy allies, 
when cold, weighed five ounces and a half. 
In another experiment, perfedtly fimilar to the fore¬ 
going, as far as relates to the compofition and quantities, 
the enkindling did not enfue till forty-one hours after 
the impregnation; the heat kept increafing for three 
hours, and then the accenfion followed. It is worthy of 
remark, that thefe experiments fucceeded better on bright 
days than on luch.as were rainy ; and the accenfion came 
on more rapidly. 
Three quarters of a pound of German rahm were (lowly 
impregnated with a pound and a half of hemp-oil varnilh. 
v I’he mixture remained leventy hours before it became 
hot and reeking ; it then gradually became hotter, and 
emitted a ftrong exhalation; the effluvia were moift, and 
not inflammable. The I'eaftion lafted thirty-fix hours, 
during which the heat was one while ftronger, and then 
weaker, and at length quite ceafed. 
Stove or chimney foot, moftly formed from birch-wood 
fmoke, was mingled with the above-mentioned fubftances 
and tied up; the compound remained cold and quiet. Ruf¬ 
fian fir-black, mixed with equal parts of oil of turpentine, 
and bound up, exhibited not the l.eaft reaction or warmth. 
Birch-oil, mixed with equal parts of Ruffian fir-black, 
and bound up, began to grow warm and to emit a vola¬ 
tile fmell; but the warmth foon went off again. 
From the experiments of the admiralty and of Mr. Geor¬ 
gi, we learn, not only the decifive certainty of the felf- 
accenfion of foot and oil, when the two fubftances are 
mixed under certain circumftances, but alfo the following 
particulars : Of the various kinds of foot, or lamp-black, 
the experiments fucceeded more frequently and furely 
with the coarfer, more undtuous, and heavier, like Ruffian 
painters’ black, than with fine light German rahm, or with 
coarfe chimney-foot. In regard to oils, only thofe expe¬ 
riments fucceeded which were made with drying oils, ei¬ 
ther raw or, boiled. The proportions of the foots to 
the oils were, in the fuccelsful experiments, very various 
the mixture kindled with a tenth, a fifth, a third, with 
an equal, and likewife with a double, proportion of oil. 
In general, however, much more depends on the mode of 
mixture, and the manipulation, and, as Mr. Georgi often 
obferved, on the weather; for in moift weather the bun¬ 
dles, after becoming warm, would frequently grow cold 
again. 
The inftances of fpontaneous inflammation hitherto 
mentioned have been only of vegetable fubftances; but 
we have examples of the fame thing in the animal king¬ 
dom. Pieces of woollen cloth, which had not been fcoured, 
took fire in a warehoufe. The fame thing happened to 
fome heaps of woollen yarn; and fome pieces of cloth 
took fire in the road, as they were going to the fuller. 
Thefe inflammations always take place where the matters 
heaped up preferve a certain degree of humidity, which 
is neceflary to excite a fermentation ; the heat refulting 
from which, by drying the oil, leads them infenfibly to a 
date of ignition ; and the quality of the oil, being more 
or lefs deliccative, very much contributes thereto. 
The woollen ftufr prepared at Cevennes, which bears the 
name of emperor’s (tuff, has kindled of itfelf, and burnt 
to a coal. It is not unufual for this to happen to wo'ol- 
len (luffs, when in hot fummers they are laid in a heap in 
a room but little aired. In June 1781, the fame thing 
happened at a wool-comber’s in a manufacturing town in 
Germany, where a heap of wool-combings, piled up in a 
clofe warehoufe feldom aired, took fire of itfelf. This 
wool had been by little and little brought into the ware¬ 
houfe; and, for want of room, piled up very high, and 
trodden down, that more might be added to it. That 
this combed wool, to which, as is well known, rape-oil 
mixed with butter is ufed in the combing, burnt of itfelf, 
was fworn by feveral witneftes. One of them affirmed 
that, ten years before, a fimilar fire happened among the 
flocks of wool at a clothier’s, who had put them into a 
calk, where they were rammed hard, for their eafier con¬ 
veyance. This wool burnt from within outwards, and 
became quite a coal; it was very certain that neither fire 
nor light had been ufed A the packing, confequently the 
above fires arofe from fimilar caufes. In like manner, 
very credible cloth-workers have certified, that, after they 
have brought wool that was become wet, and packed it 
clofe in their warehoufe, this wool has burnt of itfelf; 
and very ferious confequences might have followed, if it 
had not been difeovered in time. 
The mineral kingdom alfo often affords inftances of 
fpontaneous inflammation. Pyrites heaped up, if wetted 
and expofed to the air, take fire. Pitcoal alfo, laid in 
heaps, under certain circumftances, inflames fpontaneoufly. 
M. Duhamel has deferibed two inflammations of this na¬ 
ture, which happened in the magazines of Bred, in the 
years 
