gas employed in their experiments from mercury oxydated by heat without
addition, or, as it is called, _calcined_ or _precipitated_ per se, the
excessive dearness of that preparation would render experiments, even
upon a moderate scale, quite impracticable. But mercury may likewise be
oxydated by means of nitric acid; and in this way we procure a red oxyd,
even more pure than that produced by calcination. I have sometimes
prepared this oxyd by dissolving mercury in nitric acid, evaporating to
dryness, and calcining the salt, either in a retort, or in capsules
formed of pieces of broken matrasses and retorts, in the manner formerly
described; but I have never succeeded in making it equally beautiful
with what is sold by the druggists, and which is, I believe, brought
from Holland. In choosing this, we ought to prefer what is in solid
lumps composed of soft adhering scales, as when in powder it is
sometimes adulterated with red oxyd of lead.
To obtain oxygen gas from the red oxyd of mercury, I usually employ a
porcelain retort, having a long glass tube adapted to its beak, which is
engaged under jars in the water pneumato-chemical apparatus, and I
place a bottle in the water, at the end of the tube, for receiving the
mercury, in proportion as it revives and distils over. As the oxygen gas
never appears till the retort becomes red, it seems to prove the
principle established by Mr Berthollet, that an obscure heat can never
form oxygen gas, and that light is one of its constituent elements. We
must reject the first portion of gas which comes over, as being mixed
with common air, from what was contained in the retort at the beginning
of the experiment; but, even with this precaution, the oxygen gas
procured is usually contaminated with a tenth part of azotic gas, and
with a very small portion of carbonic acid gas. This latter is readily
got rid of, by making the gas pass through a solution of caustic alkali;
but we know of no method for separating the azotic gas; its proportions
may however be ascertained, by leaving a known quantity of the oxygen
gas contaminated with it for a fortnight, in contact with sulphuret of
soda or potash, which absorbs the oxygen gas so as to convert the
sulphur into sulphuric acid, and leaves the azotic gas remaining pure.
We may likewise procure oxygen gas from black oxyd of manganese or
nitrat of potash, by exposing them to a red heat in the apparatus
already described for operating upon red oxyd of mercury; only, as it
requires such a heat as is at least capable of softening glass, we must
employ retorts of stone or of porcelain. But the purest and best oxygen
gas is what is disengaged from oxygenated muriat of potash by simple
heat. This operation is performed in a glass retort, and the gas
obtained is perfectly pure, provided that the first portions, which are
mixed with the common air of the vessels, be rejected.
FOOTNOTES:
[61] See an account of this experiment, Part. I. Chap. iii.--A.
CHAP. IX.
_Of Deflagration._
I have already shown, Part I. Chap. IX. that oxygen does not always part
with the whole of the caloric it contained in the state of gas when it
enters into combination with other bodies. It carries almost the whole
of its caloric alongst with it in entering into the combinations which
form nitric acid and oxygenated muriatic acid; so that in nitrats, and
more especially in oxygenated muriats, the oxygen is, in a certain
degree, in the state of oxygen gas, condensed, and reduced to the
smallest volume it is capable of occupying.
In these combinations, the caloric exerts a constant action upon the
oxygen to bring it back to the state of gas; hence the oxygen adheres
but very slightly, and the smallest additional force is capable of
setting it free; and, when such force is applied, it often recovers the
state of gas instantaneously. This rapid passage from the solid to the
aeriform state is called detonation, or fulmination, because it is
usually accompanied with noise and explosion. Deflagrations are commonly
produced by means of combinations of charcoal either with nitre or
oxygenated muriat of potash; sometimes, to assist the inflammation,
sulphur is added; and, upon the just proportion of these ingredients,
and the proper manipulation of the mixture, depends the art of making
gun-powder.
As oxygen is changed, by deflagration with charcoal, into carbonic acid,
instead of oxygen gas, carbonic acid gas is disengaged, at least when
the mixture has been made in just proportions. In deflagration with
nitre, azotic gas is likewise disengaged, because azote is one of the
constituent elements of nitric acid.
The sudden and instantaneous disengagement and expansion of these gasses
is not, however, sufficient for explaining all the phenomena of
deflagration; because, if this were the sole operating power, gun powder
would always be so much the stronger in proportion as the quantity of
gas disengaged in a given time was the more considerable, which does not
always accord with experiment. I have tried some kinds which produced
almost double the effect of ordinary gun powder, although they gave out
a sixth part less of gas during deflagration. It would appear that the
quantity of caloric disengaged at the moment of detonation contributes
considerably to the expansive effects produced; for, although caloric
penetrates freely through the pores of every body in nature, it can only
do so progressively, and in a given time; hence, when the quantity
disengaged at once is too large to get through the pores of the
surrounding bodies, it must necessarily act in the same way with
ordinary elastic fluids, and overturn every thing that opposes its
passage. This must, at least in part, take place when gun-powder is set
on fire in a cannon; as, although the metal is permeable to caloric, the
quantity disengaged at once is too large to find its way through the
pores of the metal, it must therefore make an effort to escape on every
side; and, as the resistance all around, excepting towards the muzzle,
is too great to be overcome, this effort is employed for expelling the
bullet.
The caloric produces a second effect, by means of the repulsive force
exerted between its particles; it causes the gasses, disengaged at the
moment of deflagration, to expand with a degree of force proportioned to
the temperature produced.
It is very probable that water is decomposed during the deflagration of
gun-powder, and that part of the oxygen furnished to the nascent
carbonic acid gas is produced from it. If so, a considerable quantity of
hydrogen gas must be disengaged in the instant of deflagration, which
expands, and contributes to the force of the explosion. It may readily
be conceived how greatly this circumstance must increase the effect of
powder, if we consider that a pint of hydrogen gas weighs only one
grain and two thirds; hence a very small quantity in weight must occupy
a very large space, and it must exert a prodigious expansive force in
passing from the liquid to the aeriform state of existence.
In the last place, as a portion of undecomposed water is reduced to
vapour during the deflagration of gun-powder, and as water, in the state
of gas, occupies seventeen or eighteen hundred times more space than in
its liquid state, this circumstance must likewise contribute largely to
the explosive force of the powder.
I have already made a considerable series of experiments upon the nature
of the elastic fluids disengaged during the deflagration of nitre with
charcoal and sulphur; and have made some, likewise, with the oxygenated
muriat of potash. This method of investigation leads to tollerably
accurate conclusions with respect to the constituent elements of these
salts. Some of the principal results of these experiments, and of the
consequences drawn from them respecting the analysis of nitric acid, are
reported in the collection of memoirs presented to the Academy by
foreign philosophers, vol. xi. p. 625. Since then I have procured more
convenient instruments, and I intend to repeat these experiments upon a
larger scale, by which I shall procure more accurate precision in their
results; the following, however, is the process I have hitherto
employed. I would very earnestly advise such as intend to repeat some of
these experiments, to be very much upon their guard in operating upon
any mixture which contains nitre, charcoal, and sulphur, and more
especially with those in which oxygenated muriat of potash is mixed with
these two materials.
I make use of pistol barrels, about six inches long, and of five or six
lines diameter, having the touch-hole spiked up with an iron nail
strongly driven in, and broken in the hole, and a little tin-smith's
solder run in to prevent any possible issue for the air. These are
charged with a mixture of known quantities of nitre and charcoal, or any
other mixture capable of deflagration, reduced to an impalpable powder,
and formed into a paste with a moderate quantity of water. Every portion
of the materials introduced must be rammed down with a rammer nearly of
the same caliber with the barrel, four or five lines at the muzzle must
be left empty, and about two inches of quick match are added at the end
of the charge. The only difficulty in this experiment, especially when
sulphur is contained in the mixture, is to discover the proper degree of
moistening; for, if the paste be too much wetted, it will not take fire,
and if too dry, the deflagration is apt to become too rapid, and even
dangerous.
When the experiment is not intended to be rigorously exact, we set fire
to the match, and, when it is just about to communicate with the charge,
we plunge the pistol below a large bell-glass full of water, in the
pneumato chemical apparatus. The deflagration begins, and continues in
the water, and gas is disengaged with less or more rapidity, in
proportion as the mixture is more or less dry. So long as the
deflagration continues, the muzzle of the pistol must be kept somewhat
inclined downwards, to prevent the water from getting into its barrel.
In this manner I have sometimes collected the gas produced from the
deflagration of an ounce and half, or two ounces, of nitre.
In this manner of operating it is impossible to determine the quantity
of carbonic acid gas disengaged, because a part of it is absorbed by the
water while passing through it; but, when the carbonic acid is absorbed,
the azotic gas remains; and, if it be agitated for a few minutes in
caustic alkaline solution, we obtain it pure, and can easily determine
its volume and weight. We may even, in this way, acquire a tollerably
exact knowledge of the quantity of carbonic acid by repeating the
experiment a great many times, and varying the proportions of charcoal,
till we find the exact quantity requisite to deflagrate the whole nitre
employed. Hence, by means of the weight of charcoal employed, we
determine the weight of oxygen necessary for saturation, and deduce the
quantity of oxygen contained in a given weight of nitre.
I have used another process, by which the results of this experiment are
considerably more accurate, which consists in receiving the disengaged
gasses in bell-glasses filled with mercury. The mercurial apparatus I
employ is large enough to contain jars of from twelve to fifteen pints
in capacity, which are not very readily managed when full of mercury,
and even require to be filled by a particular method. When the jar is
placed in the cistern of mercury, a glass syphon is introduced,
connected with a small air-pump, by means of which the air is exhausted,
and the mercury rises so as to fill the jar. After this, the gas of the
deflagration is made to pass into the jar in the same manner as directed
when water is employed.
I must again repeat, that this species of experiment requires to be
performed with the greatest possible precautions. I have sometimes seen,
when the disengagement of gas proceeded with too great rapidity, jars
filled with more than an hundred and fifty pounds of mercury driven off
by the force of the explosion, and broken to pieces, while the mercury
was scattered about in great quantities.
When the experiment has succeeded, and the gas is collected under the
jar, its quantity in general, and the nature and quantities of the
several species of gasses of which the mixture is composed, are
accurately ascertained by the methods already pointed out in the second
chapter of this part of my work. I have been prevented from putting the
last hand to the experiments I had begun upon deflagration, from their
connection with the objects I am at present engaged in; and I am in
hopes they will throw considerable light upon the operations belonging
to the manufacture of gun-powder.
CHAP. X.
_Of the Instruments necessary for Operating upon Bodies in very high
Temperatures._
SECT. I.
_Of Fusion._
We have already seen, that, by aqueous solution, in which the particles
of bodies are separated from each other, neither the solvent nor the
body held in solution are at all decomposed; so that, whenever the cause
of separation ceases, the particles reunite, and the saline substance
recovers precisely the same appearance and properties it possessed
before solution. Real solutions are produced by fire, or by introducing
and accumulating a great quantity of caloric between the particles of
bodies; and this species of solution in caloric is usually called
_fusion_.
This operation is commonly performed in vessels called crucibles, which
must necessarily be less fusible than the bodies they are intended to
contain. Hence, in all ages, chemists have been extremely solicitous to
procure crucibles of very refractory materials, or such as are capable
of resisting a very high degree of heat. The best are made of very pure
clay or of porcelain earth; whereas such as are made of clay mixed with
calcareous or silicious earth are very fusible. All the crucibles made
in the neighbourhood of Paris are of this kind, and consequently unfit
for most chemical experiments. The Hessian crucibles are tolerably good;
but the best are made of Limoges earth, which seems absolutely
infusible. We have, in France, a great many clays very fit for making
crucibles; such, for instance, is the kind used for making melting pots
at the glass-manufactory of St Gobin.
Crucibles are made of various forms, according to the operations they
are intended to perform. Several of the most common kinds are
represented Pl. VII. Fig. 7. 8. 9. and 10. the one represented at Fig.
9. is almost shut at its mouth.
Though fusion may often take place without changing the nature of the
fused body, this operation is frequently employed as a chemical means of
decomposing and recompounding bodies. In this way all the metals are
extracted from their ores; and, by this process, they are revivified,
moulded, and alloyed with each other. By this process sand and alkali
are combined to form glass, and by it likewise pastes, or coloured
stones, enamels, &c. are formed.
The action of violent fire was much more frequently employed by the
ancient chemists than it is in modern experiments. Since greater
precision has been employed in philosophical researches, the _humid_ has
been preferred to the _dry_ method of process, and fusion is seldom had
recourse to until all the other means of analysis have failed.
SECT. II.
_Of Furnaces._
These are instruments of most universal use in chemistry; and, as the
success of a great number of experiments depends upon their being well
or ill constructed, it is of great importance that a laboratory be well
provided in this respect. A furnace is a kind of hollow cylindrical
tower, sometimes widened above, Pl. XIII. Fig. 1. ABCD, which must have
at least two lateral openings; one in its upper part F, which is the
door of the fire-place, and one below, G, leading to the ash-hole.
Between these the furnace is divided by a horizontal grate, intended
for supporting the fewel, the situation of which is marked in the figure
by the line HI. Though this be the least complicated of all the chemical
furnaces, yet it is applicable to a great number of purposes. By it
lead, tin, bismuth, and, in general, every substance which does not
require a very strong fire, may be melted in crucibles; it will serve
for metallic oxydations, for evaporatory vessels, and for sand-baths, as
in Pl. III. Fig. 1. and 2. To render it proper for these purposes,
several notches, m m m m, Pl. XIII. Fig. 1. are made in its upper
edge, as otherwise any pan which might be placed over the fire would
stop the passage of the air, and prevent the fewel from burning. This
furnace can only produce a moderate degree of heat, because the quantity
of charcoal it is capable of consuming is limited by the quantity of air
which is allowed to pass through the opening G of the ash-hole. Its
power might be considerably augmented by enlarging this opening, but
then the great stream of air which is convenient for some operations
might be hurtful in others; wherefore we must have furnaces of different
forms, constructed for different purposes, in our laboratories: There
ought especially to be several of the kind now described of different
sizes.
The reverberatory furnace, Pl. XIII. Fig. 2. is perhaps more necessary.
This, like the common furnace, is composed of the ash-hole HIKL, the
fire-place KLMN, the laboratory MNOP, and the dome RRSS, with its funnel
or chimney TTVV; and to this last several additional tubes may be
adapted, according to the nature of the different experiments. The
retort A is placed in the division called the laboratory, and supported
by two bars of iron which run across the furnace, and its beak comes out
at a round hole in the side of the furnace, one half of which is cut in
the piece called the laboratory, and the other in the dome. In most of
the ready made reverberatory furnaces which are sold by the potters at
Paris, the openings both above and below are too small: These do not
allow a sufficient volume of air to pass through; hence, as the quantity
of charcoal consumed, or, what is much the same thing, the quantity of
caloric disengaged, is nearly in proportion to the quantity of air which
passes through the furnace, these furnaces do not produce a sufficient
effect in a great number of experiments. To remedy this defect, there
ought to be two openings GG to the ash-hole; one of these is shut up
when only a moderate fire is required; and both are kept open when the
strongest power of the furnace is to be exerted. The opening of the dome
SS ought likewise to be considerably larger than is usually made.
It is of great importance not to employ retorts of too large size in
proportion to the furnace, as a sufficient space ought always to be
allowed for the passage of the air between the sides of the furnace and
the vessel. The retort A in the figure is too small for the size of the
furnace, yet I find it more easy to point out the error than to correct
it. The intention of the dome is to oblige the flame and heat to
surround and strike back or reverberate upon every part of the retort,
whence the furnace gets the name of reverberatory. Without this
circumstance the retort would only be heated in its bottom, the vapours
raised from the contained substance would condense in the upper part,
and a continual cohabitation would take place without any thing passing
over into the receiver, but, by means of the dome, the retort is equally
heated in every part, and the vapours being forced out, can only
condense in the neck of the retort, or in the recipient.
To prevent the bottom of the retort from being either heated or coolled
too suddenly, it is sometimes placed in a small sand-bath of baked clay,
standing upon the cross bars of the furnace. Likewise, in many
operations, the retorts are coated over with lutes, some of which are
intended to preserve them from the too sudden influence of heat or of
cold, while others are for sustaining the glass, or forming a kind of
second retort, which supports the glass one during operations wherein
the strength of the fire might soften it. The former is made of
brick-clay with a little cow's hair beat up alongst with it, into a
paste or mortar, and spread over the glass or stone retorts. The latter
is made of pure clay and pounded stone-ware mixed together, and used in
the same manner. This dries and hardens by the fire, so as to form a
true supplementary retort capable of retaining the materials, if the
glass retort below should crack or soften. But, in experiments which are
intended for collecting gasses, this lute, being porous, is of no manner
of use.
In a great many experiments wherein very violent fire is not required,
the reverberatory furnace may be used as a melting one, by leaving out
the piece called the laboratory, and placing the dome immediately upon
the fire-place, as represented Pl. XIII. Fig. 3. The furnace represented
in Fig. 4. is very convenient for fusions; it is composed of the
fire-place and ash-hole ABD, without a door, and having a hole E, which
receives the muzzle of a pair of bellows strongly luted on, and the dome
ABGH, which ought to be rather lower than is represented in the figure.
This furnace is not capable of producing a very strong heat, but is
sufficient for ordinary operations, and may be readily moved to any part
of the laboratory where it is wanted. Though these particular furnaces
are very convenient, every laboratory must be provided with a forge
furnace, having a good pair of bellows, or, what is more necessary, a
powerful melting furnace. I shall describe the one I use, with the
principles upon which it is constructed.
The air circulates in a furnace in consequence of being heated in its
passage through the burning coals; it dilates, and, becoming lighter
than the surrounding air, is forced to rise upwards by the pressure of
the lateral columns of air, and is replaced by fresh air from all sides,
especially from below. This circulation of air even takes place when
coals are burnt in a common chaffing dish; but we can readily conceive,
that, in a furnace open on all sides, the mass of air which passes, all
other circumstances being equal, cannot be so great as when it is
obliged to pass through a furnace in the shape of a hollow tower, like
most of the chemical furnaces, and consequently, that the combustion
must be more rapid in a furnace of this latter construction. Suppose,
for instance, the furnace ABCDEF open above, and filled with burning
coals, the force with which the air passes through the coals will be in
proportion to the difference between the specific gravity of two columns
equal to AC, the one of cold air without, and the other of heated air
within the furnace. There must be some heated air above the opening AB,
and the superior levity of this ought likewise to be taken into
consideration; but, as this portion is continually coolled and carried
off by the external air, it cannot produce any great effect.
But, if we add to this furnace a large hollow tube GHAB of the same
diameter, which preserves the air which has been heated by the burning
coals from being coolled and dispersed by the surrounding air, the
difference of specific gravity which causes the circulation will then be
between two columns equal to GC. Hence, if GC be three times the length
of AC, the circulation will have treble force. This is upon the
supposition that the air in GHCD is as much heated as what is contained
in ABCD, which is not strictly the case, because the heat must decrease
between AB and GH; but, as the air in GHAB is much warmer than the
external air, it follows, that the addition of the tube must increase
the rapidity of the stream of air, that a larger quantity must pass
through the coals, and consequently that a greater degree of combustion
must take place.
We must not, however, conclude from these principles, that the length of
this tube ought to be indefinitely prolonged; for, since the heat of the
air gradually diminishes in passing from AB to GH, even from the contact
of the sides of the tube, if the tube were prolonged to a certain
degree, we would at last come to a point where the specific gravity of
the included air would be equal to the air without; and, in this case,
as the cool air would no longer tend to rise upwards, it would become a
gravitating mass, resisting the ascension of the air below. Besides, as
this air, which has served for combustion, is necessarily mixed with
carbonic acid gas, which is considerably heavier than common air, if the
tube were made long enough, the air might at last approach so near to
the temperature of the external air as even to gravitate downwards;
hence we must conclude, that the length of the tube added to a furnace
must have some limit beyond which it weakens, instead of strengthening
the force of the fire.
From these reflections it follows, that the first foot of tube added to
a furnace produces more effect than the sixth, and the sixth more than
the tenth; but we have no data to ascertain at what height we ought to
stop. This limit of useful addition is so much the farther in proportion
as the materials of the tube are weaker conductors of heat, because the
air will thereby be so much less coolled; hence baked earth is much to
be preferred to plate iron. It would be even of consequence to make the
tube double, and to fill the interval with rammed charcoal, which is one
of the worst conductors of heat known; by this the refrigeration of the
air will be retarded, and the rapidity of the stream of air consequently
increased; and, by this means, the tube may be made so much the longer.
As the fire-place is the hottest part of a furnace, and the part where
the air is most dilated in its passage, this part ought to be made with
a considerable widening or belly. This is the more necessary, as it is
intended to contain the charcoal and crucible, as well as for the
passage of the air which supports, or rather produces the combustion;
hence we only allow the interstices between the coals for the passage of
the air.
From these principles my melting furnace is constructed, which I believe
is at least equal in power to any hitherto made, though I by no means
pretend that it possesses the greatest possible intensity that can be
produced in chemical furnaces. The augmentation of the volume of air
produced during its passage through a melting furnace not being hitherto
ascertained from experiment, we are still unacquainted with the
proportions which should exist between the inferior and superior
apertures, and the absolute size of which these openings should be made
is still less understood; hence data are wanting by which to proceed
upon principle, and we can only accomplish the end in view by repeated
trials.
This furnace, which, according to the above stated rules, is in form of
an eliptical spheroid, is represented Pl. XIII. Fig. 6. ABCD; it is cut
off at the two ends by two plains, which pass, perpendicular to the
axis, through the foci of the elipse. From this shape it is capable of
containing a considerable quantity of charcoal, while it leaves
sufficient space in the intervals for the passage of the air. That no
obstacle may oppose the free access of external air, it is perfectly
open below, after the model of Mr Macquer's melting furnace, and stands
upon an iron tripod. The grate is made of flat bars set on edge, and
with considerable interstices. To the upper part is added a chimney, or
tube, of baked earth, ABFG, about eighteen feet long, and almost half
the diameter of the furnace. Though this furnace produces a greater heat
than any hitherto employed by chemists, it is still susceptible of being
considerably increased in power by the means already mentioned, the
principal of which is to render the tube as bad a conductor of heat as
possible, by making it double, and filling the interval with rammed
charcoal.
When it is required to know if lead contains any mixture of gold or
silver, it is heated in a strong fire in capsules of calcined bones,
which are called cuppels. The lead is oxydated, becomes vitrified, and
sinks into the substance of the cuppel, while the gold or silver, being
incapable of oxydation, remain pure. As lead will not oxydate without
free access of air, this operation cannot be performed in a crucible
placed in the middle of the burning coals of a furnace, because the
internal air, being mostly already reduced by the combustion into azotic
and carbonic acid gas, is no longer fit for the oxydation of metals. It
was therefore necessary to contrive a particular apparatus, in which the
metal should be at the same time exposed to the influence of violent
heat, and defended from contact with air rendered incombustible by its
passage through burning coals. The furnace intended for answering this
double purpose is called the cuppelling or essay furnace. It is usually
made of a square form, as represented Pl. XIII. Fig. 8. and 10. having
an ash-hole AABB, a fire-place BBCC, a laboratory CCDD, and a dome DDEE.
The muffle or small oven of baked earth GH, Fig. 9. being placed in the
laboratory of the furnace upon cross bars of iron, is adjusted to the
opening GG, and luted with clay softened in water. The cuppels are
placed in this oven or muffle, and charcoal is conveyed into the furnace
through the openings of the dome and fire-place. The external air enters
through the openings of the ash-hole for supporting the combustion, and
escapes by the superior opening or chimney at EE; and air is admitted
through the door of the muffle GG for oxydating the contained metal.
Very little reflection is sufficient to discover the erroneous
principles upon which this furnace is constructed. When the opening GG
is shut, the oxydation is produced slowly, and with difficulty, for want
of air to carry it on; and, when this hole is open, the stream of cold
air which is then admitted fixes the metal, and obstructs the process.
These inconveniencies may be easily remedied, by constructing the muffle
and furnace in such a manner that a stream of fresh external air should
always play upon the surface of the metal, and this air should be made
to pass through a pipe of clay kept continually red hot by the fire of
the furnace. By this means the inside of the muffle will never be
coolled, and processes will be finished in a few minutes, which at
present require a considerable space of time.
Mr Sage remedies these inconveniencies in a different manner; he places
the cuppel containing lead, alloyed with gold or silver, amongst the
charcoal of an ordinary furnace, and covered by a small porcelain
muffle; when the whole is sufficiently heated, he directs the blast of a
common pair of hand-bellows upon the surface of the metal, and completes
the cuppellation in this way with great ease and exactness.
SECT. III.
_Of increasing the Action of Fire, by using Oxygen Gas instead of
Atmospheric Air._
By means of large burning glasses, such as those of Tchirnausen and Mr
de Trudaine, a degree of heat is obtained somewhat greater than has
hitherto been produced in chemical furnaces, or even in the ovens of
furnaces used for baking hard porcelain. But these instruments are
extremely expensive, and do not even produce heat sufficient to melt
crude platina; so that their advantages are by no means sufficient to
compensate for the difficulty of procuring, and even of using them.
Concave mirrors produce somewhat more effect than burning glasses of the
same diameter, as is proved by the experiments of Messrs Macquer and
Beaume with the speculum of the Abbe Bouriot; but, as the direction of
the reflected rays is necessarily from below upwards, the substance to
be operated upon must be placed in the air without any support, which
renders most chemical experiments impossible to be performed with this
instrument.
For these reasons, I first endeavoured to employ oxygen gas for
combustion, by filling large bladders with it, and making it pass
through a tube capable of being shut by a stop-cock; and in this way I
succeeded in causing it to support the combustion of lighted charcoal.
The intensity of the heat produced, even in my first attempt, was so
great as readily to melt a small quantity of crude platina. To the
success of this attempt is owing the idea of the gazometer, described p.
308. _et seq._ which I substituted instead of the bladders; and, as we
can give the oxygen gas any necessary degree of pressure, we can with
this instrument keep up a continued stream, and give it even a very
considerable force.
The only apparatus necessary for experiments of this kind consists of a
small table ABCD, Pl. XII. Fig. 15, with a hole F, through which passes
a tube of copper or silver, ending in a very small opening at G, and
capable of being opened or shut by the stop-cock H. This tube is
continued below the table at l m n o, and is connected with the
interior cavity of the gazometer. When we mean to operate, a hole of a
few lines deep must be made with a chizel in a piece of charcoal, into
which the substance to be treated is laid; the charcoal is set on fire
by means of a candle and blow-pipe, after which it is exposed to a
rapid stream of oxygen gas from the extremity G of the tube FG.
This manner of operating can only be used with such bodies as can be
placed, without inconvenience, in contact with charcoal, such as metals,
simple earths, &c. But, for bodies whose elements have affinity to
charcoal, and which are consequently decomposed by that substance, such
as sulphats, phosphats, and most of the neutral salts, metallic glasses,
enamels, &c. we must use a lamp, and make the stream of oxygen gas pass
through its flame. For this purpose, we use the elbowed blow-pipe ST,
instead of the bent one FG, employed with charcoal. The heat produced in
this second manner is by no means so intense as in the former way, and
is very difficultly made to melt platina. In this manner of operating
with the lamp, the substances are placed in cuppels of calcined bones,
or little cups of porcelain, or even in metallic dishes. If these last
are sufficiently large, they do not melt, because, metals being good
conductors of heat, the caloric spreads rapidly through the whole mass,
so that none of its parts are very much heated.
In the Memoirs of the Academy for 1782, p. 476. and for 1783, p. 573.
the series of experiments I have made with this apparatus may be seen at
large. The following are some of the principal results.
1. Rock cristal, or pure silicious earth, is infusible, but becomes
capable of being softened or fused when mixed with other substances.
2. Lime, magnesia, and barytes, are infusible, either when alone, or
when combined together; but, especially lime, they assist the fusion of
every other body.
3. Argill, or pure base of alum, is completely fusible _per se_ into a
very hard opake vitreous substance, which scratches glass like the
precious stones.
4. All the compound earths and stones are readily fused into a brownish
glass.
5. All the saline substances, even fixed alkali, are volatilized in a
few seconds.
6. Gold, silver, and probably platina, are slowly volatilized without
any particular phenomenon.
7. All other metallic substances, except mercury, become oxydated,
though placed upon charcoal, and burn with different coloured flames,
and at last dissipate altogether.
8. The metallic oxyds likewise all burn with flames. This seems to form
a distinctive character for these substances, and even leads me to
believe, as was suspected by Bergman, that barytes is a metallic oxyd,
though we have not hitherto been able to obtain the metal in its pure or
reguline state.
9. Some of the precious stones, as rubies, are capable of being softened
and soldered together, without injuring their colour, or even
diminishing their weights. The hyacinth, tho' almost equally fixed with
the ruby, loses its colour very readily. The Saxon and Brasilian topaz,
and the Brasilian ruby, lose their colour very quickly, and lose about a
fifth of their weight, leaving a white earth, resembling white quartz,
or unglazed china. The emerald, chrysolite, and garnet, are almost
instantly melted into an opake and coloured glass.
10. The diamond presents a property peculiar to itself; it burns in the
same manner with combustible bodies, and is entirely dissipated.
There is yet another manner of employing oxygen gas for considerably
increasing the force of fire, by using it to blow a furnace. Mr Achard
first conceived this idea; but the process he employed, by which he
thought to dephlogisticate, as it is called, atmospheric air, or to
deprive it of azotic gas, is absolutely unsatisfactory. I propose to
construct a very simple furnace, for this purpose, of very refractory
earth, similar to the one represented Pl. XIII. Fig. 4. but smaller in
all its dimensions. It is to have two openings, as at E, through one of
which the nozle of a pair of bellows is to pass, by which the heat is to
be raised as high as possible with common air; after which, the stream
of common air from the bellows being suddenly stopt, oxygen gas is to be
admitted by a tube, at the other opening, communicating with a gazometer
having the pressure of four or five inches of water. I can in this
manner unite the oxygen gas from several gazometers, so as to make eight
or nine cubical feet of gas pass through the furnace; and in this way I
expect to produce a heat greatly more intense than any hitherto known.
The upper orifice of the furnace must be carefully made of considerable
dimensions, that the caloric produced may have free issue, lest the too
sudden expansion of that highly elastic fluid should produce a dangerous
explosion.
FINIS.
APPENDIX.
No. I.
TABLE _for Converting Lines, or Twelfth Parts of an Inch, and Fractions
of Lines, into Decimal Fractions of the Inch._
Twelfth Parts Decimal Decimal
of a Line. Fractions. Lines. Fractions.
1 0.00694 1 0.08333
2 0.01389 2 0.16667
3 0.02083 3 0.25000
4 0.02778 4 0.33333
5 0.03472 5 0.41667
6 0.04167 6 0.50000
7 0.04861 7 0.58333
8 0.05556 8 0.66667
9 0.06250 9 0.75000
10 0.06944 10 0.83333
11 0.07639 11 0.91667
12 0.08333 12 1.00000
No. II.
TABLE _for Converting the Observed Heighths of Water in the Jars of the
Pneumato-Chemical Apparatus, expressed in Inches and Decimals, into
Corresponding Heighths of Mercury._
Water. Mercury. Water. Mercury.
.1 .00737 4. .29480
.2 .01474 5. .36851
.3 .02201 6. .44221
.4 .02948 7. .51591
.5 .03685 8. .58961
.6 .04422 9. .66332
.7 .05159 10. .73702
.8 .05896 11. .81072
.9 .06633 12. .88442
1. .07370 13. .96812
2. .14740 14. 1.04182
3. .22010 15. 1.11525
No. III.
TABLE _for Converting the Ounce Measures used by Dr Priestly into French
and English Cubical Inches._
Ounce French cubical English cubical
measures. inches. inches.
1 1.567 1.898
2 3.134 3.796
3 4.701 5.694
4 6.268 7.592
5 7.835 9.490
6 9.402 11.388
7 10.969 13.286
8 12.536 15.184
9 14.103 17.082
10 15.670 18.980
20 31.340 37.960
30 47.010 56.940
40 62.680 75.920
50 78.350 94.900
60 94.020 113.880
70 109.690 132.860
80 125.360 151.840
90 141.030 170.820
100 156.700 189.800
1000 1567.000 1898.000
No. IV. ADDITIONAL.
TABLE _for Reducing the Degrees of Reaumeur's Thermometer into its
corresponding Degrees of Fahrenheit's Scale._
R. F. R. F. R. F. R. F.
0 = 32 21 = 79.25 41 = 124.25 61 = 169.25
1 = 34.25 22 = 81.5 42 = 126.5 62 = 171.5
2 = 36.5 23 = 83.75 43 = 128.75 63 = 173.75
3 = 38.75 24 = 86 44 = 131 64 = 176.
4 = 41 25 = 88.25 45 = 133.25 65 = 178.25
5 = 43.25 26 = 90.5 46 = 135.5 66 = 180.5
6 = 45.5 27 = 92.75 47 = 137.75 67 = 182.75
7 = 47.75 28 = 95 48 = 140 68 = 185
8 = 50 29 = 97.25 49 = 142.25 69 = 187.25
9 = 52.25 30 = 99.5 50 = 144.5 70 = 189.5
10 = 54.5 31 = 101.75 51 = 146.75 71 = 191.75
11 = 56.75 32 = 104 52 = 149 72 = 194.
12 = 59 33 = 106.25 53 = 151.25 73 = 196.25
13 = 61.25 34 = 108.5 54 = 153.5 74 = 198.5
14 = 63.5 35 = 110.75 55 = 155.75 75 = 200.75
15 = 65.75 36 = 113 56 = 158 76 = 203
16 = 68 37 = 115.25 57 = 160.25 77 = 205.25
17 = 70.25 38 = 117.5 58 = 162.5 78 = 207.5
18 = 72.5 39 = 119.75 59 = 164.75 79 = 209.75
19 = 74.75 40 = 122 60 = 167 80 = 212
20 = 77
_Note_--Any degree, either higher or lower, than what is contained in
the above Table, may be at any time converted, by remembering that one
degree of Reaumeur's scale is equal to 2.25 deg. of Fahrenheit; or it
may be done without the Table by the following formula, R x 9 / 4 + 32 = F;
that is, multiply the degree of Reaumeur by 9, divide the product by 4,
to the quotient add 32, and the sum is the degree of Fahrenheit.--E.
No. V. ADDITIONAL.
RULES _for converting French Weights and Measures into correspondent
English Denominations[62]._
Sec. 1. _Weights._
The Paris pound, poids de mark of Charlemagne, contains 9216 Paris
grains; it is divided into 16 ounces, each ounce into 8 gros, and each
gros into 72 grains. It is equal to 7561 English Troy grains.
The English Troy pound of 12 ounces contains 5760 English Troy grains,
and is equal to 7021 Paris grains.
The English averdupois pound of 16 ounces contains 7000 English Troy
grains, and is equal to 8538 Paris grains.
To reduce Paris grs. to English Troy }
grs. divide by } 1.2189
To reduce English Troy grs. to Paris }
grs. multiply by }
To reduce Paris ounces to English }
Troy, divide by }
To reduce English Troy ounces to } 1.015734
Paris, multiply by }
Or the conversion may be made by means of the following Tables.
I. _To reduce French to English Troy Weight._
The Paris pound = 7561 }
The ounce = 472.5625 } English.
The gros = 59.0703 } Troy.
The grain = .8194 } Grains.
II. _To Reduce English Troy to Paris Weight._
The English Troy pound } = 7021. }
of 12 ounces } }
The Troy ounce = 585.0830 }
The dram of 60 grs. = 73.1353 } Paris
The penny weight, or } = 29.2540 } grains.
denier, of 24 grs. } }
The scruple, of 20 grs. = 24.3784 }
III. _To Reduce English Averdupois to Paris Weight._
The averdupois pound of } }
16 ounces, or 7000 } = 8538. } Paris
Troy grains. } } grains.
The ounce = 533.6250 }
Sec. 2. _Long and Cubical Measures._
To reduce Paris feet or inches into }
English, multiply by } 1.065977
English feet or inches into Paris, }
divide by }
To reduce Paris cubic feet or inches }
to English, multiply by }
English cubic feet or inches to Paris, } 1.211278
divide by }
Or by means of the following tables:
IV. _To Reduce Paris Long Measure to English._
The Paris royal foot of } }
12 inches } = 12.7977 } English
The inch = 1.0659 }
The line, or 1/12 of an inch = .0888 } inches.
The 1/12 of a line = .0074 }
V. _To Reduce English Long Measure to French._
The English foot = 11.2596 }
The inch = .9383 }
The 1/8 of an inch = .1173 } Paris inches.
The 1/10 = .0938 }
The line, or 1/12 = .0782 }
VI. _To Reduce French Cube Measure to English._
The Paris } English { }
cube foot = 1.211278 } cubical { 2093.088384 }
The cubic } feet, { } inches.
inch = .000700 } or { 1.211278 }
VII. _To Reduce English Cube Measure to French._
The English cube foot, }
or 1728 cubical inches } = 1427.4864 } French
The cubical inch = .8260 } cubical
The cube tenth = .0008 } inches.
Sec. 3. _Measure of Capacity._
The Paris pint contains 58.145[63] English cubical inches, and the
English wine pint contains 28.85 cubical inches; or, the Paris pint
contains 2.01508 English pints, and the English pint contains .49617
Paris pints; hence,
To reduce the Paris pint to the English, }
multiply by } 2.01508.
To reduce the English pint to the }
Paris, divide by }
No. VI.
TABLE _of the Weights of the different Gasses, at 28 French inches, or
29.84 English inches barometrical pressure, and at 10 deg. (54.5 deg.) of
temperature, expressed in English measure and English Troy weight._
Names of the Gasses. Weight of a Weight of a
cubical inch. cubical foot.
(A) qrs. oz. dr. qrs.
Atmospheric air .32112 1 1 15
Azotic gas .30064 1 0 39.5
Oxygen gas .34211 1 1 51
Hydrogen gas .02394 0 0 41.26
Carbonic acid gas .44108 1 4 41
(B)
Nitrous gas .37000 1 2 39
Ammoniacal gas .18515 0 5 19.73
Sulphurous acid gas .71580 2 4 38
[Note A: These five were ascertained by Mr Lavoisier himself.--E.]
[Note B: The last three are inserted by Mr Lavoisier upon the authority
of Mr Kirwan.--E.]
No. VII.
_Tables_ _of the Specific Gravities of different bodies._
Sec. 1. _Metallic Substances._
GOLD.
Pure gold of 24 carats melted but not hammered 19.2581
The same hammered 19.3617
Gold of the Parisian standard, 22 carats fine, not hammered(A) 17.4863
The same hammered 17.5894
Gold of the standard of French coin, 21-22/32 carats fine,
not hammered 17.4022
The same coined 17.6474
Gold of the French trinket standard, 20 carats fine,
not hammered 15.7090
The same hammered 15.7746
[Note A: The same with Sterling.]
SILVER.
Pure or virgin silver, 24 deniers, not hammered 10.4743
The same hammered 10.5107
Silver of the Paris standard, 11 deniers 10 grains fine,
not hammered(B) 10.1752
The same hammered 10.3765
Silver, standard of French coin, 10 deniers 21 grains
fine, not hammered 10.0476
The same coined 10.4077
[Note B: This is 10 grs. finer than Sterling.]
PLATINA.
Crude platina in grains 15.6017
The same, after being treated with muriatic acid 16.7521
Purified platina, not hammered 19.5000
The same hammered 20.3366
The same drawn into wire 21.0417
The same passed through rollers 22.0690
COPPER AND BRASS.
Copper, not hammered 7.7880
The same wire drawn 8.8785
Brass, not hammered 8.3958
The same wire drawn 8.5441
IRON AND STEEL.
Cast iron 7.2070
Bar iron, either screwed or not 7.7880
Steel neither tempered nor screwed 7.8331
Steel screwed but not tempered 7.8404
Steel tempered and screwed 7.8180
Steel tempered and not screwed 7.8163
TIN.
Pure tin from Cornwall melted and not screwed 7.2914
The same screwed 7.2994
Malacca tin, not screwed 7.2963
The same screwed 7.3065
Molten lead 11.3523
Molten zinc 7.1908
Molten bismuth 9.8227
Molten cobalt 7.8119
Molten arsenic 5.7633
Molten nickel 7.8070
Molten antimony 6.7021
Crude antimony 4.0643
Glass of antimony 4.9464
Molybdena 4.7385
Tungstein 6.0665
Mercury 13.5681
Sec. 2. _Precious Stones._
White Oriental diamond 3.5212
Rose-coloured Oriental ditto 3.5310
Oriental ruby 4.2833
Spinell ditto 3.7600
Ballas ditto 3.6458
Brasillian ditto 3.5311
Oriental topas 4.0106
Ditto Pistachio ditto 4.0615
Brasillian ditto 3.5365
Saxon topas 3.5640
Ditto white ditto 3.5535
Oriental saphir 3.9941
Ditto white ditto 3.9911
Saphir of Puy 4.0769
Ditto of Brasil 3.1307
Girasol 4.0000
Ceylon jargon 4.4161
Hyacinth 3.6873
Vermillion 4.2299
Bohemian garnet 4.1888
Dodecahedral ditto 4.0627
Syrian ditto 4.0000
Volcanic ditto, with 24 sides 2.4684
Peruvian emerald 2.7755
Crysolite of the jewellers 2.7821
Ditto of Brasil 2.6923
Beryl, or Oriental aqua marine 3.5489
Occidental aqua marine 2.7227
Sec. 3. _Silicious Stones._
Pure rock cristal of Madagascar 2.6530
Ditto of Brasil 2.6526
Ditto of Europe, or gelatinous 2.6548
Cristallized quartz 2.6546
Amorphous ditto 2.6471
Oriental agate 2.5901
Agate onyx 2.6375
Transparent calcedony 2.6640
Carnelian 2.6137
Sardonyx 2.6025
Prase 2.5805
Onyx pebble 2.6644
Pebble of Rennes 2.6538
White jade 2.9502
Green jade 2.9660
Red jasper 2.6612
Brown ditto 2.6911
Yellow ditto 2.7101
Violet ditto 2.7111
Gray ditto 2.7640
Jasponyx 2.8160
Black prismatic hexahedral schorl 3.3852
Black spary ditto 3.3852
Black amorphous schorl, called antique basaltes 2.9225
Paving stone 2.4158
Grind stone 2.1429
Cutler's stone 2.1113
Fountainbleau stone 2.5616
Scyth stone of Auvergne 2.5638
Ditto of Lorrain 2.5298
Mill stone 2.4835
White flint 2.5941
Blackish ditto 2.5817
Sec. 4. _Various Stones, &c._
Opake green Italian serpentine, or gabro of the Florentines 2.4295
Coarse Briancon chalk 2.7274
Spanish chalk 2.7902
Foliated lapis ollaris of Dauphiny 2.7687
Ditto ditto from Sweden 2.8531
Muscovy talc 2.7917
Black mica 2.9004
Common schistus or slate 2.6718
New slate 2.8535
White rasor hone 2.8763
Black and white hone 3.1311
Rhombic or Iceland cristal 2.7151
Pyramidal calcareous spar 2.7141
Oriental or white antique alabaster 2.7302
Green Campan marble 2.7417
Red Campan marble 2.7242
White Carara marble 2.7168
White Parian marble 2.8376
Various kinds of calcareous stones } from 1.3864
used in France for building. } to 2.3902
Heavy spar 4.4300
White fluor 3.1555
Red ditto 3.1911
Green ditto 3.1817
Blue ditto 3.1688
Violet ditto 3.1757
Red scintilant zeolite from Edelfors 2.4868
White scintilant zeolite 2.0739
Cristallized zeolite 2.0833
Black pitch stone 2.0499
Yellow pitch stone 2.0860
Red ditto 2.6695
Blackish ditto 2.3191
Red porphyry 2.7651
Ditto of Dauphiny 2.7033
Green serpentine 2.8960
Black ditto of Dauphiny, called variolite 2.9339
Green ditto from Dauphiny 2.9883
Ophites 2.9722
Granitello 3.0626
Red Egyptian granite 2.6541
Beautiful red granite 2.7609
Granite of Girardmas 2.7163
Pumice stone .9145
Lapis obsidianus 2.3480
Pierre de Volvic 2.3205
Touch stone 2.4153
Basaltes from Giants Causeway 2.8642
Ditto prismatic from Auvergne 2.4153
Glass gall 2.8548
Bottle glass 2.7325
Green glass 2.6423
White glass 2.8922
St Gobin cristal 2.4882
Flint glass 3.3293
Borax glass 2.6070
Seves porcelain 2.1457
Limoges ditto 2.3410
China ditto 2.3847
Native sulphur 2.0332
Melted sulphur 1.9907
Hard peat 1.3290
Ambergrease .9263
Yellow transparent amber 1.0780
Sec. 5. _Liquids._
Distilled water 1.0000
Rain water 1.0000
Filtered water of the Seine 1.00015
Arcueil water 1.00046
Avray water 1.00043
Sea water 1.0263
Water of the Dead Sea 1.2403
Burgundy wine .9915
Bourdeaux ditto .9939
Malmsey Madeira 1.0382
Red beer 1.0338
White ditto 1.0231
Cyder 1.0181
Highly rectified alkohol .8293
Common spirits of wine .8371
Alkohol 15 pts. water 1 part. .8527
14 2 .8674
13 3 .8815
12 4 .8947
11 5 .9075
10 6 .9199
9 7 .9317
8 8 .9427
7 9 .9519
6 10 .9594
5 11 .9674
4 12 .9733
3 13 .9791
2 14 .9852
1 15 .9919
Sulphuric ether .7394
Nitric ether .9088
Muriatic ether .7298
Acetic ether .8664
Sulphuric acid 1.8409
Nitric ditto 1.2715
Muriatic ditto 1.1940
Red acetous ditto 1.0251
White acetous ditto 1.0135
Distilled ditto ditto 1.0095
Acetic ditto 1.0626
Formic ditto .9942
Solution of caustic ammoniac, or volatil alkali fluor .8970
Essential or volatile oil of turpentine .8697
Liquid turpentine .9910
Volatile oil of lavender .8938
Volatile oil of cloves 1.0363
Volatile oil of cinnamon 1.0439
Oil of olives .9153
Oil of sweet almonds .9170
Lintseed oil .9403
Oil of poppy seed .9288
Oil of beech mast .9176
Whale oil .9233
Womans milk 1.0203
Mares milk 1.0346
Ass milk 1.0355
Goats milk 1.0341
Ewe milk 1.0409
Cows milk 1.0324
Cow whey 1.0193
Human urine 1.0106
Sec. 6. _Resins and Gums_
Common yellow or white rosin 1.0727
Arcanson 1.0857
Galipot(A) 1.0819
Baras(A) 1.0441
Sandarac 1.0920
Mastic 1.0742
Storax 1.1098
Opake copal 1.1398
Transparent ditto 1.0452
Madagascar ditto 1.0600
Chinese ditto 1.0628
Elemi 1.0182
Oriental anime 1.0284
Occidental ditto 1.0426
Labdanum 1.1862
Ditto _in tortis_ 2.4933
Resin of guaiac 1.2289
Ditto of jallap 1.2185
Dragons blood 1.2045
Gum lac 1.1390
Tacamahaca 1.0463
Benzoin 1.0924
Alouchi(B) 1.0604
Caragna(C) 1.1244
Elastic gum .9335
Camphor .9887
Gum ammoniac 1.2071
Sagapenum 1.2008
Ivy gum(D) 1.2948
Gamboge 1.2216
Euphorbium 1.1244
Olibanum 1.1732
Myrrh 1.3600
Bdellium 1.3717
Aleppo Scamony 1.2354
Smyrna ditto 1.2743
Galbanum 1.2120
Assafoetida 1.3275
Sarcocolla 1.2684
Opoponax 1.6226
Cherry tree gum 1.4817
Gum Arabic 1.4523
Tragacanth 1.3161
Basora gum 1.4346
Acajou gum(E) 1.4456
Monbain gum(F) 1.4206
Inspissated juice of liquorice 1.7228
---- Acacia 1.5153
---- Areca 1.4573
Terra Japonica 1.3980
Hepatic aloes 1.3586
Socotrine aloes 1.3795
Inspissated juice of St John's wort 1.5263
Opium 1.3366
Indigo .7690
Arnotto .5956
Yellow wax .9648
White ditto .9686
Ouarouchi ditto(G) .8970
Cacao butter .8916
Spermaceti .9433
Beef fat .9232
Veal fat .9342
Mutton fat .9235
Tallow .9419
Hoggs fat .9368
Lard .9478
Butter .9423
[Note A: Resinous juices extracted in France from the Pine. _Vide
Bomare's Dict._]
[Note B: Odoriferous gum from the tree which produces the Cortex
Winteranus. _Bomare._]
[Note C: Resin of the tree called in Mexico Caragna, or Tree of Madness.
_Ibid._]
[Note D: Extracted in Persia and the warm countries from Hedera
terrestris.--_Bomare._]
[Note E: From a Brasilian tree of this name.--_Ibid._]
[Note F: From a tree of this name.--_Ibid._]
[Note G: The produce of the Tallow Tree of Guayana. _Vide Bomare's
Dict._]
Sec. 7. _Woods._
Heart of oak 60 years old 1.1700
Cork .2400
Elm trunk .6710
Ash ditto .8450
Beech .8520
Alder .8000
Maple .7550
Walnut .6710
Willow .5850
Linden .6040
Male fir .5500
Female ditto .4980
Poplar .3830
White Spanish ditto .5294
Apple tree .7930
Pear tree .6610
Quince tree .7050
Medlar .9440
Plumb tree .7850
Olive wood .9270
Cherry tree .7150
Filbert tree .6000
French box .9120
Dutch ditto 1.3280
Dutch yew .7880
Spanish ditto .8070
Spanish cypress .6440
American cedar .5608
Pomgranate tree 1.3540
Spanish mulberry tree .8970
Lignum vitae 1.3330
Orange tree .7050
_Note_--The numbers in the above Table, if the Decimal point be carried
three figures farther to the right hand, nearly express the absolute
weight of an English cube foot of each substance in averdupois ounces.
See No. VIII. of the Appendix.--E.
No. VIII. ADDITIONAL.
RULES _for Calculating the Absolute Gravity in English Troy Weight of a
Cubic Foot and Inch, English Measure, of any Substance whose Specific
Gravity is known[64]._
In 1696, Mr Everard, balance-maker to the Exchequer, weighed before the
Commissioners of the House of Commons 2145.6 cubical inches, by the
Exchequer standard foot, of distilled water, at the temperature of 55 deg.
of Fahrenheit, and found it to weigh 1131 oz. 14 dts. Troy, of the
Exchequer standard. The beam turned with 6 grs. when loaded with 30
pounds in each scale. Hence, supposing the pound averdupois to weigh
7000 grs. Troy, a cubic foot of water weighs 62-1/2 pounds averdupois,
or 1000 ounces averdupois, wanting 106 grains Troy. And hence, if the
specific gravity of water be called 1000, the proportional specific
gravities of all other bodies will nearly express the number of
averdupois ounces in a cubic foot. Or more accurately, supposing the
specific gravity of water expressed by 1. and of all other bodies in
proportional numbers, as the cubic foot of water weighs, at the above
temperature, exactly 437489.4 grains Troy, and the cubic inch of water
253.175 grains, the absolute weight of a cubical foot or inch of any
body in Troy grains may be found by multiplying their specific gravity
by either of the above numbers respectively.
By Everard's experiment, and the proportions of the English and French
foot, as established by the Royal Society and French Academy of
Sciences, the following numbers are ascertained.
Paris grains in a Paris cube foot of water = 645511
English grains in a Paris cube foot of water = 529922
Paris grains in an English cube foot of water = 533247
English grains in an English cube foot of water = 437489.4
English grains in an English cube inch of water = 253.175
By an experiment of Picard with the measure and
weight of the Chatelet, the Paris cube foot of
water contains of Paris grains = 641326
By one of Du Hamel, made with great care = 641376
By Homberg = 641666
These show some uncertainty in measures or in weights; but the above
computation from Everard's experiment may be relied on, because the
comparison of the foot of England with that of France was made by the
joint labours of the Royal Society of London and the French Academy of
Sciences: It agrees likewise very nearly with the weight assigned by Mr
Lavoisier, 70 Paris pounds to the cubical foot of water.
No. IX.
TABLES _for Converting Ounces, Drams, and Grains, Troy, into Decimals of
the Troy Pound of 12 Ounces, and for Converting Decimals of the Pound
Troy into Ounces, &c._
I. _For Grains._
Grains = Pound.
1 .0001736
2 .0003472
3 .0005208
4 .0006944
5 .0008681
6 .0010417
7 .0012153
8 .0013889
9 .0015625
10 .0017361
20 .0034722
30 .0052083
40 .0069444
50 .0086806
60 .0104167
70 .0121528
80 .0138889
90 .0156250
100 .0173611
200 .0374222
300 .0520833
400 .0694444
500 .0868055
600 .1041666
700 .1215277
800 .1388888
900 .1562499
1000 .1736110
2000 .3472220
3000 .5208330
4000 .6944440
5000 .8680550
6000 1.0418660
7000 1.2152770
8000 1.3888880
9000 1.5624990
II. _For Drams._
Drams = Pound.
1 .0104167
2 .0208333
3 .0312500
4 .0416667
5 .0520833
6 .0625000
7 .0729167
8 .0833333
III. _For Ounces._
Ounces = Pounds.
1 .0833333
2 .1666667
3 .2500000
4 .3333333
5 .4166667
6 .5000000
7 .5833333
8 .6666667
9 .7500000
10 .8333333
11 .9166667
12 1.0000000
IV. _Decimals of the Pound into Ounces, &c._
_Tenth parts._
lib. = oz. dr. gr.
0.1 1 1 36
0.2 2 3 12
0.3 3 4 48
0.4 4 6 24
0.5 6 0 0
0.6 7 1 36
0.7 8 3 12
0.8 9 4 48
0.9 10 6 24
_Hundredth parts._
0.01 0 0 57.6
0.02 0 1 55.2
0.03 0 2 52.8
0.04 0 3 50.4
0.05 0 4 48.0
0.06 0 5 45.6
0.07 0 6 43.2
0.08 0 7 40.8
0.09 0 3 38.4
_Thousandths._
0.001 0 0 5.76
0.002 0 0 11.52
0.003 0 0 17.28
0.004 0 0 23.04
0.005 0 0 28.80
lib. = grs.
0.006 34.56
0.007 40.32
0.008 46.08
0.009 51.84
_Ten thousandth parts._
0.0001 0.576
0.0002 1.152
0.0003 1.728
0.0004 2.304
0.0005 2.880
0.0006 3.456
0.0007 4.032
0.0008 4.608
0.0009 5.184
_Hundred thousandth parts._
0.00001 0.052
0.00002 0.115
0.00003 0.173
0.00004 0.230
0.00005 0.288
0.00006 0.346
0.00007 0.403
0.00008 0.461
0.00009 0.518
No. X.
TABLE _of the English Cubical Inches and Decimals corresponding to a
determinate Troy Weight of Distilled Water at the Temperature of 55 deg.,
calculated from Everard's experiment._
_For Grains._
Grs. Cubical inches.
1 = .0039
2 .0078
3 .0118
4 .0157
5 .0197
6 .0236
7 .0275
8 .0315
9 .0354
10 .0394
20 .0788
30 .1182
40 .1577
50 .1971
_For Drams._
Drams. Cubical inches.
1 = .2365
2 .4731
3 .7094
4 .9463
5 1.1829
6 1.4195
7 1.6561
_For Ounces._
Oz. Cubical inches.
1 = 1.8927
2 3.7855
3 5.6782
4 7.5710
5 9.4631
6 11.3565
7 13.2493
8 15.1420
9 17.0748
10 18.9276
11 20.8204
_For Pounds._
Libs. Cubical inches.
1 = 22.7131
2 45.4263
3 68.1394
4 90.8525
5 113.5657
6 136.2788
7 158.9919
8 181.7051
9 204.4183
10 227.1314
50 1135.6574
100 2271.3148
1000 22713.1488
FOOTNOTES:
[62] For the materials of this Article the Translator is indebted to
Professor Robertson.
[63] It is said, _Belidor Archit. Hydrog._ to contain 31 oz. 64 grs.
of water, which makes it 58.075 English inches; but, as there is
considerable uncertainty in the determinations of the weight of the
French cubical measure of water, owing to the uncertainty of the
standards made use of, it is better to abide by Mr Everard's measure,
which was with the Exchequer standards, and by the proportions of the
English and French foot, as established by the French Academy and Royal
Society.
[64] The whole of this and the following article was communicated to the
Translator by Professor Robinson.--E.
_THE PLATES_
[Illustration: _Plate I_]
[Illustration: _Plate I (continued)_]
[Illustration: _Plate II_]
[Illustration: _Plate II (continued)_]
[Illustration: _Plate III_]
[Illustration: _Plate III (continued)_]
[Illustration: _Plate IV_]
[Illustration: _Plate IV (continued)_]
[Illustration: _Plate V_]
[Illustration: _Plate V (continued)_]
[Illustration: _Plate VI_]
[Illustration: _Plate VI (continued)_]
[Illustration: _Plate VII_]
[Illustration: _Plate VII (continued)_]
[Illustration: _Plate VIII_]
[Illustration: _Plate VIII (continued)_]
[Illustration: _Plate IX_]
[Illustration: _Plate IX (continued)_]
[Illustration: _Plate X_]
[Illustration: _Plate X (continued)_]
[Illustration: _Plate XI_]
[Illustration: _Plate XI (continued)_]
[Illustration: _Plate XII_]
[Illustration: _Plate XII (continued)_]
[Illustration: _Plate XII (continued)_]
[Illustration: _Plate XII (continued)_]
[Illustration: _Plate XII (continued)_]
[Illustration: _Plate XIII_]
[Illustration: _Plate XIII (continued)_]
THE END.
End of Project Gutenberg's Elements of Chemistry,, by Antoine Lavoisier