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Induction, science knows that physical truths cannot be compared tends to demonstrate, must be evident to intuition or Inductions

with moral truths, nor the truths of pure mathematics experience, otherwise the premises could not be known
with either.

to be true. The analyfis of a few fyllogisms will make
That the method of induction is a just logic, has this apparent to every reader.
been fufficiently evinced elsewhere (see LOGIC, Part Dr Wallis, who, to an intimate acquaintance with
III. chap. V. and PHILOSOPHY, n° 73–78. Encycl.), the Ariftotelian logic, ad ted much mathematical and
and is now indeed generally admitted. It is even ad- physical knowledge, gives the following fyllogism as a
mitted by British philosophers to be the only method perfect example of this mode of reasoning in the firit
of reasoning by which any progress can be made in the figure, to which it is known that all the other figures
physical sciences ; for the laws of Nature can be discovers may be reduced :
ed only by accurate experiments, and by carefully noting

Omne animal eft fenfu preditum.
the agreements and the differences, however minute,
which are thus found among the phenomena apparently

Socrates est animal. Ergo

Socrates eft fenfu preditus.
fimilar. It is not, however, commonly said that induce
tion is the method of reasoning employed by the mathe- Here the propofition to be demonstrated is, that So.
maticians ; and the writer of this article long thought, crates is endowed with sense; and the propofitions af.
with others, that in pure geometry the re.foning is fumed as self-evident truths, upon which the demonflra.

ftrialy Syllogistical. Mature reflection, however, has tion is to be built, are, that “ every animal is endowed * Appendix led him to doubt, with Doctor Reid *, the truth of the with sense;" and that “ Socrates is an animal.” But

Vol of Sletebes generally received opinion, to donbt even whether by how comes the demonftrator to know that " every ani. of the Hiffo. categorical fyllogisms any thing whatever can be proved. mal is endowed with fense?" To this queftion we are ng of Man

To tlie idolaters of Aristotle we are perfectly aware not aware of any answer which can be given, excepc
that this will appear an extravagant paradox ; but to the this, that mankind have agreed to call every being,
votaries of truth, we do not despair of making it very which they perceive to be endowed with fense, ani ani.
evident, that for such doubts there is some foundation. mal. Let this, then, be supposed the true answer : the

We are led into this disquifition to counteract, in some next question to be put to the demonttrator is, How he
degree, what we think the pernicious tendency of the comes to know that Socrates is an animal? If we have
philosophy of Kant, which attempts have been lately answered the former qeretion properly, or, in other
made to introduce into this country. Of this philofo. words, if it be effential to this genus of beings to be
phy we shall endeavour to give something like a diftinet endowed with fense, it is obvious chikt he can know that
view in the proper place. It is fufficient to observe Socrates is an animal only by perceiving him to be en-
here, that it rests upon the hypothesis, that “ we are in dowed with jense; and therefore, in this fyllogism, the
poffeffion of certain notions à priori, which are abso. proposition to be proved is the very firft of the three of
lutely independent of all exptrience, although the objets of which the truth is perceived; and it is perceived intui.
experience correspond with them; and which are distin. tively, and nor inferred from others by a process of rea-
guished by neceflity and strict univerfality." These innate foning.
and universal notions, Kant confiders as a ft of cate- Though there are terr categories and five predi-
gories, from which is to be deduced all such knowledge eables, there are but two kinds of categorical propoli-
as deserves the name of science; and he talks, of course, tions, viz Those in which the property or accident is
or at least his English translators represent him talking, predicated of the fubitance to which it belongs, and
with great cortempt, of induqive reasoning, and subili. those in which the genus is predicated of the ffecies of
tuting syllogiftic demonttration in its stead.

individual. Of the former kind is the propofition pre.
As his categories are not familiar to our readers, we tended to be proved by the fyllogism which we have
fħall, in this place, examine syllogisms connected with considered; of the latter, is that which is proved by the
the categories of Ariftotle, which are at lealt more in. following:
telligible than those of Kant, and which, being likewise

Quicquid sensu præditum, eft animal.
general notions, muit, in argument, be managed in the

Socrates eft fenfu præditus. ' Ergo
fame way. Now the fundamental axiom upon which

Socrates eft animal.
every categorical fyllogifm refts, is the well known pro-
polution, which affirms, that " whatever may be predi. That this is a categorical syllogifm, legitimate in
cated of a whole genus, may be predicated of every fpe- mode and figure, will be denied by no man who is stot
cies and of every individual comprehended under that an absohute itranger to the very firft principles of the
genus." This is indeed an undoubted truth ; but it Ariftotelian logic; but it requires little attention indeed
cannot constitute a foundation for reasoning from the to perceive that it proves nothing. The impofition of
genus to the species or the individual; because we cannot names is a thing so perfectly arbitrary, that the being,
poflibly know what can be predicated of the genus till or class of beings, which in Latin and English is called
we know what can be predicated of all the individuals animal, is with equal propriety in Greek called swer, and
ranged under it.. Indeed it is only by ascertaining, in Hebrew vs. To a native of Greece, therefore, and
through the medium of indu&tion, what can be predi- to an ancient Hebrew, the major proposition of this
gated, and what not, of a number of individuals, that fyllogism would have been wholly unintelligible ; but
we come to form such notions as those of genera and had either of those persons been told by a man of known
Species; and therefore, in a fyllogism striAly categorical, veracity, and acquainted with the Latin tongue, that
the propofitions, which conftitute the premises, and are every thing endowed with sense was, by the Romans,
taken for granted, are those alone which are capable of called animal, he would then have understood the pro.
proof; whilft the conclufion, which the logician pre- pofition, admitted its truth without hesitation, and have

benceforth

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Induction, henceforth known that Socrates and Mofes, and every is merely to Morten the different processes of geometri. Iadu Peipner

thing else which he perceived to be endowed with sense, cal reasoning, and not, as has sometimes been absurdly
would at Rome be called animal, This knowledge, supposed, to be made the parents or causes of parti-
however, would not have reited upou demonstrative rea- cular truths. No truth, whether general or particular,
foning of ary kind, but upon the credibility of his in, can, in any sense of the word, be the cause of another
former, and the intuitive evidence of his own senses. truth. If it were not true that ait individual figures,

It will perhaps be said, that the two fyllogisms which of whatever form, comprehending a portion of ipace
we have examined are improper examples, becaule the equal to a portion comprehended by any other indivi.
truth to be proved by the former is felf.evident, whilft dual figure, whether of the same form with some of
that which is meant to be establithed by the latter is them, or of a form different from them all, are equal to
merely verbal, and therefore arbitrary. But the follow one another, it would not be true that “things in ge-
ing is liable to neither of these objections :

neral, which are equal to the same thing, or that mag. All animals are mortal.

nitudes which coincide, or exactly fill the same space," Man is an animal; therefore

are respectively equal to one another; and therefore the

first and eight of Euclid's axioms would be false. So
Man is mortal.

far are these axioms, or general truths, from being the
Here it would be proper to ask the demonstrator, up. parents of particular truths, that, as conceived by us, they
on what grounds he so confidently pronounces all ani. may, with greater propriery, be termed their offspring.
mals to be mortal? The proposition is so far from ex. They are indeed nothing more than general expressions,
prelling a felf evident truth, that, previous to the en- comprehending all particular truths of the same kind.
cance of fin and death into the world, the firtt man When a mathematical proposition therefore is enounced,
had surely no conception of mortality. He acquired if the terms, of which it is composed, or the figures of
the notion, however, by experience, when he saw the which a cercain relation is predicated, can be brought toge-
animals die in succession around him ; and when he ob- ther and immediately compared, no deinonftration is ne-
ferved that no animal with which he was acquainted, ceffary to point out its truth or falsehood. It is indeed in.
not even his own son, escaped death, he would conclude tuitively perceived to be either comprehended under, or
that all animals, without exception, are mortal. This contrary to some known axiom of the science; but it has
conclulion, however, could not be built upon syllogistic the evidence of truth or falsehood in itself, and not in
reasoning, nor yet upon intuition, but partly upon ex- confequence of that axiom. When the figures or symbols
perience and partly on ‘analogy. As far as bis expe- cannot be immediately compared tog ther, it is then,
sience went, the proof, by induction, of the mortality and only then, that recourse is had to demonftration
of all animals was complete ; but there are many ani- which proceeds, not in a series of syllogisms, but by a
mals in the ocean, and perhaps on the earth, which he process of ideal mensuration or induction. A figure or
never law, and of whole mortality therefore he could symbol is conceived, which may be compared with each
affirm nothing but from analogy, i. e. from concluding, of the principal figures or symbols, or, if that cannot
as the conititution of the human mind compels us to be, with one of them, and then another, which may te
conclude, that Nature is uniform throughout the uni. compared with it, till through a series of well known
verse, and that fimilar causes, whether kuown or un- intermediate relations, a comparison is made between
known, will, in fimilar circumftances, produce, at all the terms of the original proposition, of which the truth
times, fimilar eifects. It is to be observed of this syllo- or falsehood is then perceived.
gism, as of the first which we have considered, that the Thus in the 47th proposition of the first book of
propofition, which it pretends to demonftrate, is one of Euclid's Elements, the author proposes to demonstrate
thote truths known by experience, from which, by the the equality between the square of the hypothenuse of
process of induction, we infer the major of the premises a right angled triangle, and the sum of the squares de.
to be true; and that therefore the realoning, it reasoning fcribed on the other two fides; but he does not proceed
it can be called, runs in a circle.

in the way of categorical syllogisms, by raising his de-
Yet by a concatenation of fyllogisms have logicians monftration on some universal truth relating to the ge-
pretended that a long series of important truths may nus of Squares. On the contrary, he proceeds to mea.
be discovered and demonstrated; and even Wallis him. sure the three squares of which he has afirmed a certain
self seems to think, that this is the inftrument by which relation ; but as they cannot be immediately compared
the mathematicians have deduced, finm a few poftulates, together, he directs the largest of them to be divided
accurate definitions, and undeniable axioms, all the truths into two parallelograms, according to a rule which he had
of their demonftrative science. Let us try the truth formerly ascertained to be just; and as these parallelo.
of this opinion by analysing some of Euclid's demon. grams can, as little as the square of which they are the
ftrations.

constituent parts, be compared with the squares of the In the Mort article PRINCIPLE (Encycl.), it has been other two sides of the triangle, he thinks of some inter. Mewn, that all our first truths are particular, and that it mediate figure which may be applied as a common mea. is by applying to them the rules of induction that we fure to the squares and the parallelograms. Accordingform general truths or axioms-even the axioms of pure ly, having before found that a parallelogram, or square, geometry. As this science treats not of real external is exactly double of a triangle standing on the same bale things, but merely of ideas or conceptions, the creatures and between the saine parallels with it, he constructs of our minds, it is obvious, that its definitions may be triangles upon the fame base, and between the fame pa. perfe&tly accurate, the induction by which its axioma rallels with his parallelograms, and the squares of the are formed complete, and therefore the axiomi them- fides containir.g the right angle of the original triangle; selves universal propositions. The use of these axioms and finding, by a process formerly hewn to be jutt,

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Induction that the triangles on the base of the parallelograms are of them is clearly perceived to be impossible ; whilst inductions

precisely equal to the triangles on the bases of the physical truths are all contingent, so that there is not
squares, he perceives at once that the two parallelo. one of them of which the direct contrary may not
grams, of which the largest square is composed, mu!t easily be conceived ?
be equal to the sum of the two lesser squares ; and the That there is not one phyfical truth, of which the
truth of the propofition is demonstrated.

contrary may not be conceived, is not perhaps fo cer.
In the course of this demonstration, there is not fo tain as his generally been imagined; but admitting the
much as one truth inferred from another by Syllogilin, fact to be as it has commonly been tated, the app.
but all are perceived in succession by a series of simple rent difference between this class of truths and those of
apprehenfons. Euclid, indeed, after finding the triangle pure geometry, may be easily accounted for, without
constructed on the base of one of the parallelograms to fuppoiing that the former rests upon a kind of evia
be equal to the triangle constructed on the base of one dence totally different from that which supports the fa-
of the squares, introduces an axiom, and says, “but bric of the latter.
the doubles of equals are equal to one another ; there- The objects of pure geometry, as we have already ob.
fore the parallelogram is equal to the square.". But served, are ihe creatures of our own minds, which con-
if from this mode of expreflion any man conceive the tain in them nothing concealed from our view.
axiom or universal cruth to be the cause of the truth the mathematician tieats them merely as measurable
more particular, or fuppose that the latter could not quuntities, he knows, with the utmost precision, upon
be apprehended without a previous knowledge of the for. what particular properties the relation affirmed to fub.
mer, he is a stranger to the nature of evidence, and to fitt between any iwo or more of them must absolutely
the process of generalization, by which axioms are form- deperd ; and he cannot posibly entertain a doubt but
ed.

it will be found to have place among all quantities
If we examine the problems of this ancient geome. having the same properties, because it depends upon
trician, we shall find that the truth of them is proved them, and upon them alone. His process of induction,
by the very fame means which he makrs ufe of to therefore, by a series of ideal measurements, is always
point out the truth of his theorems. Thus, the fitt complete, and exhausts the subject ; but in phyfical en.
problem of his immortal work is, “ to describe an equi. quiries the case is widely different. The subjects which
lateral triangle on a given finite ftraight line;" and not employ the phyfical enquirer are not his own ideas, and
only is this to be done, but the method by which it is their various relacions, but the properties, powers, and
done must be such as can be shewn to be incontroverti relations of the bodies which compose the universe ;
bly juft. The sides of a triangle, however, cannot be ap. and of those bodies he knows neither the substance, in.
plied to each other so as to be immediately compared; ternal Aructure, nor all the qualities : so that he can
for they are conceived to be immoveable among them very seldom discover with certainty upon what parti-
felves. sl common measue, therefore, or something cular property or properties the phenomena of the core
equivalent to a corrmon measure, must be found, by poreal world, or the relations which sublist among dif.
which the triangle may be constructed, and the equa- ferent bodies, depend. He expects, indeed, with confi.
lity of its three sides ofterwards evinced ; and this equi. dence, not inferior to that with which he admits a mathe-
valent Euclid finds in the circle.

matical demonstration, that any corporeal phenomenon, By contemplating the properties of the circle, it was which he has observed in certain circumstances, will be easy to perceive that all its radii must be equal to one always observed in circumftances exactly fimilar; but another. He therefore directs two circles to be de: the mi fortune is, that he can very seldom be ascertain. scribed from the opposite extremities of the given fi. ed of this fimilarity. He does not know any one piece nite straight lire, fo 28 that it may be the radius of of matter as it is in itself; he cannot separate its various each of them; and from the point in which the circles properties ; and of course cannot attribute to any one interfc&t one another, he orders lines to be drawn to property the effects or apparent effects which proceed the extreme points of the given line, affirming that exclusively from it. Indeed, the properties of bodies these three lines conftirute an equilateral triangle. To are fo clofely interwoven, that by human means they convince his reader of the truth of this affirmation, he cannot be completely separated ; and hence the most has only to put him in mind, that from the properties cautious inveftigator is apt to attribute to fome one or of the circle, the lines which he has drawn must be two properties, an event which in reality results per. each equal to the given line, and of course all the three haps from many. (See PHILOSOPHY and Physics, equal to one another; and this mutual equality is per Encycl.) This the geometrician never does. He ceived by simple apprehenfion, and not inferred by fyl

. knows perfectly that the relation of equality which logistic reasoning. Euclid, indeed, by introducing in. sublifts between the three angles of a plain triangle to the demonftration his first axiom, gives to it the and two right angles, depends not upon the fize of the form of a fyllogism: but that fyllogism proves nothing; triangles, the matter of which they are conceived to be for if the equality of the three sides of the triangle were made, the particular place which they occupy in the not intuitively perceived in their position and the pro- universe, or upon any one circumstance whatever be perties of the circle, the forft axiom would itself be a fides their triangularity, and the angles of their corro. falschood. So true it is that categorical fyllogisms lets being exactly right angles; and it is upon this have nu place in geometrical reafuning : which is as power of discrimination which we have in the concepftri&ly experimental and inductive as the reafoving em. tions of pure geometry, and have not in the objects of ployed in the various branches of physics.

physics, that the truths of the one science are perceiBut if this be so, how come the truths of pure geo. ved to be necessary, while those of the other appear to be mctry to be necessary, so that the contrary of any one contingent; though the mode of demonstration is the

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Inertia, faine in both, or at least equally removed from cate. ing of a lick cow in the cow.house. Mr Rüde knew, IflammaJoflammagorical fyllogifıns.

that the countrymen were used to lay an application of tion.

INERTIA. See DYNAMICS and IMPULSION in parched rye bran to their cattle for curing the thick this Supplement

neck; he knew also, that alum and rye bran, by a pro. INFLAMMATION has been sufficiently explain. per process, yielded a pyrophorus ; and now he wished ed in the Encyclopedia, and in the article CHEMISTRY to try whether parched rye bran alone would have the in this Suppl. ment; but it cannot be improper, in this fame effect. Accordingly, he roasted a quantity of rye. place, to give an account of fome remarkable

bran by the fire, till it had acouired the colour of roaste
Spontaneous INFLAMMATIONS, which, as different fib- ed coffee. This roasted bran hre wrapped up in a linen
ftances, are liable to them, have been, and may again cloth; in the space of a few minutes there arose a strong
be, the cause of many and great misfortunes.

smoke through the cloth, accompanied by a smell of
The fpontaneous inflammation of essential oils, and burning. Not long afterwards the rag grew as black
that of some fat oils, when mixed with nitrous acid, as tinder, and the bran, now become hot, fell through
are well kr.own to philofophers ; so also is that of pow. it on the ground in little balls. Mr Rüde repeated
dered charcoal with the same acid (lately discovered by the experiment at various times, and always with the
M. Prouft), and those of phosphorus, of pyrophorus, fame result. Who now will any longer doubt, that the
and of fulminating gold. These substances are general. frequency of fires in cow-houses, which in those parts
ly to be found only in the laboratories of chemilts, who are mostly wooden buildings, may not be occasioned by
are perfectly well acquamted with the precautions which this common practice, of binding roafted bran about
it is necellary to take to prevent the unhappy accidents the necks of the cattle? The fire, after consuming
which
may be occafioned by them.

the cattle and the hed, communicates ilfilf to the ad-
The burning of a kore house of fails, which happen. joining buildings; great damage ensues ; and the ig-
ed at Brest in the year 17,7, was caused by the spon. porant look for the cause in wilful and malicious firing,
laneous inflammation of some oiled cloths, which, after consequently in a capital crime.”
having been painted on one lide and dried in the sun, The fame author informy us, that in the spring of

were itowed away while yet warm; as was fhewn by the year 178 , a fire was discovered on board a Russian • See Me fubfequent experiments".

frigare lying in the road of Cronftadt ; which, if it had Vegetables boiled in oil or fat, and left to them. not been timely extinguished, would have endangered

selves, after having been presled, in Aame in the open the whole fleet. After the severeft scrutiny, no cause
de Paris,
3700.

air. This inflammation always takes place when the of the fire was to be found ; and the matter was forced
vegetabl. s retain a certain degree of humidity; if they to remain without explanation, but with strong furmises
are first thoroughly dried, they are reduced to ashes, of some wicked incendiary being at the botiom of it.

without the appearance of flame. We owe the obser. In the month of Augutt, in the same year, a fire broke
+ Fournal de vation of these facts to MM. Saladin and Carette t.
I

out at the hemp-magazine at St Petersburgh, by which The heaps of linen rigs which are thrown together several hundred thousand poods $ of hemp and flax were t A pood 1784. in paper manufaétories, the preparation of which is consumed. The walls of the magazine are of brick, confits of

haltened by means of fermentation, often take fire, if the floors of stone, and the rafters and covering of iron ; to pounds not carefully attended to.

it Itands alone on an island in the Neva, on which, as

Ruis, or 36

Euglich The spontaneous inflammation of hay has been known well as on board the hips lying in the Neva, no fire is for ma!!y centuries ; by its means houses, barns, &c. permitted. In St Petersburgh, in the same year, a fire have been ofter reduced to ashes. When the hay is was discovered in the vauited (hop of a fúrrier. In laid up damp, the inflammation often happens ; for the these mops, which are all vaults, neither fire nor candle fermentatioo is then ve:y great. This accident very is allowed, and the doors of them are all of iron. At feldom occurs to the first hay (according to the obfer- length the probable cause was found to be, that the vation of M. de Bonare), but is much more common to furrier, the evening before the fire, had got a roll of the second ; and if, through inattention, a piece of iron new cere-cloth (much in use here for covering tables, should be left in a stalk of hay in fermentation, the in- counters, &c. being eahly wiped and kept clean), and flammation of that stalk is almost a certain consequence. had left it in his vault, where it was found almoit conCorn heaped up has also sometimes produced infiamma. {umed. tions of this nature. Vanieri, in his Prædium Rufticum, In the night between the 20th and zift of April says,

1781, a fire was seen on board the frigate Maria, which Que vero (gramina) nondum fatis infolata recondens. · lay at anchor, with several other this, in the road off

the island of Cronstadt; the fire was, however, foon ex. Inprudens, subitis pariunt incendia flammis.

tinguished ; and, by the feverett examination, little or
Dung also, under certain circumstances, infames spon- nothing could be extorted corcerning the manner in
taneously.

which it had arisen. The garıison was threatened with
In a paper, published in the Repertory of Arts and a scrutiny that should cost them dear; and while they
Manufaflures, by the Rev. William Tooke, F. R. S. were in this cruel state of fufpence, an order came from
&c. we have the following remarkable instances of spon. the sovereign, which quieted their minds, and gave rise
taneous inflammation. A perfon of the name of to some very fatisfactory experiments.
Rüde, an apothecary at Bautzen, had prepared a py. It having been found, upon juridical examination, as
rophorus from rye bran and alumn. Not long after he well as private inquiry, that in the ship's cabin, when
had made the discovery, there broke out, in the next the smoke appeared, there lay a bundle of matting,
village of Nauftz, a great fire, which did much mil containing Ruffian lamp black prepared from tir foot,
chief, and was said to have been occasioned by the treat- moistened with hemp oil varnith, which was perceived

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Inflamma to have sparks of fire in it at the time of the extinction, unlike that of boiling oil. Some parts of it became Inflanıma. tion.

the Russian admiralty gave orders to make various ex- warm, and steamed much ; this fteam was watery, and
periments, in order to sec whether a mixture of hemp. by no means inflammable. Eighteen hours after the
oil varnish and the forementioned Rufian black, folded mixture was wrapped up, one place became brown, e.
up in a mat and bound together, would kindle of itself. mitted smoke, and directly afterwards glowing fire ap.

They shook 40 pounds of-for-wood foot into a tub, peared. The same thing happened in a second and a
and poured about 35 pounds of hemp oil varnish upon third place, though other places were scarcely warm.
it ; this they let stand for an hour, after which they The fire crept Nowly around, and gave a thick, grey,
poured off the oil. The remaining mixture they now itinking smoke. Mr Georgi took the bundle out of

.
wrapped up in a mat, and the bundle was laid close to the chelt, and laid it on a stone pavement; when, on
the cabin, where the midshipmen had their birth. To being exposed to the free air, there arose a slow burn-
avoid all suspicion of treachery, two officers sealed both ing Hame, a span high, with a strong body of smoke.
the mat and the door with their own seals, and ftation- Not long afterwards there appeared, here and there,
ed a watch of four sea-officers, to take notice of all several chaps or clefts, as from a little volcano, the va.
that passed the whole night through; and as soon as pour issuing from which burit into fame. On his break-
uny smoke should appear, immediately to give informa- ing the lump, it burit into a very violent fiame, full
tion to the commandant of the port.

three feet high, which foon grew less, and then went
The experiment was made the 26th of April, about out. The smoking and glowing fire lasted for the space
11 o'clock A. M. in presence of all the officers named of fix hours ; and afterwards the remainder continued
in the commission. Early on the following day, about to glow without finoke for two hours longer. The
fix o'clock A. M. a smoke appeared, of which the chief grey earthy ashes, when cold, weighed five ounces and
commandant was immediately informed by an officer:
he came with all poflible speed, and through a finall In another experiment, perfectly fimilar to the fores
hole in the door saw the mat smoking. Without open- going, as far as relates to the composition and quanti-
ing the door, he dispatched a messenger to the members ties, the enkindling did not ensue till 41 hours after the
of the commillion ; but as the smoke became stronger, impregnation : the beat kept increaling for three hours,
and fire began to appear, the chief commandant found and then the accenfion followed. It is worthy of re-
it necessary, without waiting for the members of the mark, that these experiments succeeded better on bright
commiffion, to break the seals and open the door. No days than on such as were rainy; and the accension game
fooner was the air thus admitted, than the mat began on more rapidly.
to burn with greater force, and presently it burst into In another experiment, three pounds of Russian fir-
a fame.

black were flowly in pregnated with three pounds of
The Ruffian admiralty, being now fully convinced raw hemp-oil; and the accenfon ensued after nine hours.
of the self-enkindling property of this composition, Three quarters of a pound of German rabm were
transmitted their experiment to the Imperial Academy flowly impregnated with a pound and a half of hemp-
of Sciences ; who appointed Mr Georgi, a very learned oil varnish. The mixture remained 70 hours before it
and able adjunct of the academy, to make farther experi- became hot and reeking it then gradually became hot.
ments on the subject. Previous to the relation of these ter, and emitted a Atrong exhalation ; the eMuvia were
experiments, it is necessary to observe, that the Ruffian moitt, and not inflammable. The reaction lasted 36
fir-black is three or four times more heavy, thick, and hours, during which the heat was one while Itronger,
un&tuous, than that kind of painters black which the and then weaker, and at length quite ceased.
Germans call kien-rahm. The former is gathered at Stove or chimney foot, mostly formed from birch-
Ochta, near St Petersburgh, at Mosco, at Archangel, vood smoke, was mingled with the above-mentioned
and other places, in little wooden huts, from refinous substances and tied up; the compound remained cold
fir-wood, and the unetuous bark of birch, by means of and quiet.
an apparatus uncommonly fimple, conlifting of pots Ruffian fir-black, mixed with equal parts of oil of tur.
without bottoms set one upon the other; and is sold pentine, and bound up, exhibited not the lealt reaction
very cheap. The famous fine German kien-rahm is cal. or warmth.
led in Russia Holland's black. In what follows, when Birch oil, mixed with equal parts of Ruffian fire
raw oil is spoken of, it is to be understood of linseed. black, and bound up, began to grow warm and to emit
oil or hemp oil; but most commonly the latter. The a volatile smell ; but the warmth soon went off again,
varnish is made of five pounds of hemp oil boiled with I'rom the experiments of the admiralty and of Mr
{wo ounces and a half of minium. For wrapping up Georgi, we learn, not only the decilive certainty of the
the composition, Mr Georgi made use of coarse hemp self-accenfion of foot and oil, when the two fubtances
linen, and always single, never double. The impregna. are mixed under certain circuittances, but also the fol-
tions and commixtures were made in a large wooden lowing particulars :
bowl, in which they stood open till they were wrapped

Of the various kinds of foot, or lamp-black, the ex

periments fucceeded more frequently and surely with Three pounds of Ruflian fir-black were slowly im- the coarser, more unetuous, and heavier, like Russian pregnated with five pounds of hemp-oil varnish; and painters black, than with fine light German rahm, or when the mixture had flood open five hours, it was with coarse chimney-foot. In regard to oils, only those bound up in linen. By this process it became clotted; experiments succeeded which were inade with drying oils, but some of the black remained dry. When the bundle either raw or boiled. The proportions of the foots to had lain fixteen hours in a chelt, it was observed to the oils were, in the successful experiments, very vari, emit a very nauseous, and rather patrid, smell, not quiteous; the mixture kindled with a tenth, a fifth, a third,

a

up in linen.

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