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A Aesaen
A
JOURNAL
OF
NATURAL PHILOSOPHY,
CHEMISTRY,
AND
ue
TH Po A RTS.
VOL. XVII
——as
Jllustrated with Cngravings.
BY WILLIAM NICHOLSON.
Roc * LONDON:
PRINTED BY W. STRATFORD, CROWN COURT, TEMPLE EAR; FOR
THE AUTHOR,
AND SOLD BY
J. STRATFORD, No. 112, Hoxsorn-Hixt.
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1807.
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TCAD ‘ ae
PREFACE.
Tue Authors of Original Papers and Communications
in the present Volume are, W.H. Wollaston, Sec. R.S.;
Mr. W. Skrimshire, Jun.; W.W.; Mr. John Tatum,
Jun.; Emeritus; R.T.; W. X.
_ Of Foreign Works, C. A. Prieur; C. L. Cadet;
M. Desormes; M. Clement; M. Proust; M. Bouillon La-
grange; Dr. Samuel L. Mitchell; M. Antony Alexis Cadet
de Vaux; M. Vauquelin; M. Antony Thillaye-Plat ;
F. F. Delaroche; M. Lamarck ; M. De Lalande; M. La-
places John Michael Haussman; M. Guyton; Dr. Hal-
dat; M. Henry; M. Darso; M. Gehlen; M. Erman;
M. Delaville; M. Dupont de Nemours; M. Planche;
M.And.deGy; M.Chaptal; M. Germon; C. H. Pfaff;
M. J. J. Champollion Figeac; M. Roswag; M. Belle-
mére ; Messrs. Von Humboldt and Gay-Lussac; M. Cotte;
M. Carnot.
_ And of British Memoirs abridged or extracted, Benjamin
Count of Rumford; Richard Phillips, Esq.; Dr. W. Rox-
burg; Mr. Charles Wilson; Mr. Robert Salmon; Mr. John
Austin; Mr. Jessop; M.G. Field; J. Curwen, Esq. M.P.;
Mr. Charles Waistell; Mr. John Trotter; Mr. James
_ Hardie; Rev. James Headrick.
The Engravings consist of 1. Camera Lucida, by W.
Hyde Wollaston, M.D. Sec. R.S.; 2. Decomposition of
Light, by C. A. Prieur; 3, 4. Apparatus of Mr. Thillaye
Platel for the Carbonization of Turf; 5. Mr. Tatum’s
Apparatus for ascertaining the Increase of ‘Temperature
by the Galvanic Action; 6. Theory of Looming, or Hori- —
zontal Refraction; 7. Mr. Salmon’s Specimens of good
and bad Pruning of Fir Trees; 8. Mr. Field’s Stove for
_ heating or drying; 9. Mr. Waistell’s Horse Hoe; 10. Mr.
Curwen’s Weed Harrow; 11. Apparatus for triturating
Quicksilver; 12. Erman’s new Classes of Galvanic Con-
ductors; 13. Mr. J. Trotter’s Curvilinear Saw; 14. Mr.
_ J. Hardie’s Bookbinder’s Cutting Press.
TABLE
TABLE OF CONTENTS
TO THIS SEVENTEENTH VOLUME.
JUNE, 1807.
Engravings of the following Objects: 1. Camera Lucida, by W. cyte Wol-
-laston, M.D. Sec. R..S, 2: Decompostion of Light.
I. Description of the Camera Lucida. By W. H. Wollaston, See. RS: Page I
VW. Description of a new Boiler constructed with a View to the saving oF Fuel.
By Benjamin Count of Rumford. © Read at a Meeting Pi tha first Glass’ of the
National Institute the 6th October, 1806. 5
UI. Notice of an Experiment on the Use of the Heat of are in Place of
that of an open Fire, in the making of Soap, By Benjamin Count of Rum-
ford. Read ata Meeting of the glee Class of the ge ia Institute, the
. 20th of October, 1806, - supa A 730
IV. On the Habitudes of Saline Bodies with Regard to Electricity. By ee Ww io
liam Skrimshire, Jun. Communicated by Mr. Cuthbertson.
Y. On the Decomposition of Light into its most simple Elements: a =e
of a Work on Colours, by C, A. Prieur, formerly Colonel in the Corps of
Engineers, and Lecturer in the National Institution. - 18,
“WI. Wooden Matches for Artillery, to be used- instead of Ro e Match, or Port-
Fires: read at the National Institute, April 1806. By C. L. Cadet. . 31
YIT. Letter from a Correspondent on the Mears of desing the Inseets which
-— infest the Houses in large Towns. - - 38
VIII. Theory of the Fabrication of Sa Acid; readin the Class of Physi-
cal and Mathematical Sciences of the French National Institute, January the
20th, 1806. By Messrs. Desormes and Clement. - - 4}
IX. Facts toward a History of Bigs and of Nickel. By Mr. Proust ; abridged
~* by Mr. Chevreuil. - * - 4
X, Facts toward a History of the Gallic Acid. By Bouillon Lagrange. 58
XI. Observations on the Soda, Magnesia, and Lime, contained in Water of
the Ocean; showing that they operate advantageously there by neutralizing
Acids, and:among others the Septic Acid, and that Sea Water may be ren-
dered fit for washing Clothes as the _ of eg By Samuel L. Mit-
chill, of New York - - 72
MIT. An Account of thé Improvement of an extensive Tract of Land. By
Richard Phillips, Esq. - e a i. 14
XH. Scientific News - - - ts as
“JULY,
CONTENTS. | %
JULY, 1807. ©
ai Supplementary Number to Vol. XVI.
Engravings of the following Objects; 1..and 2. Apparatus of M. Thillaye Platet-
or the Carbonization of Turf. 3. Mr. Tatum’s Apparatus for ascertaining
- the Increase of ‘Temperature by the Galvanic Action. '
I. Facts toward a History of Prussiates. By Mr. Proust ~ - Page 89
Il.. A Table.of the Growth of Trees in the Botanic Garden at Calcutta. By
_ Dr. Wm, Roxburgh - - - ae 110
Il. Extract from’a Dissertation on Coffee, its History, Properties, and the
Mode of obtaining from it the most pleasant, wholesome, and economicat
Beverage. By Antony Alexis Cadet de Vaux, Member of various Acade-
“mies: with its Analysis, by Charles Lewis Cadet, Apothecary in ordinary to
his Majesty the Emperor, Professor of Chemistry, &c, - 113
TV. Account of the Existence of Platina in the Silver Mines of Guadalcanal,
_ inthe Province of Estremadura. By M. Vauquelin - 128
Y. Carbonization of Turf, or Process by which all possible advantage may be
derived from Products hitherto neglected in that Operation, executed in the
Year of the Republic 11. By Antony Thillaye-Platel, House Apothecary at
. the Hotel-Dieu at Paris. > - Ae tt itm 131
VI. Method of curing Damp Walls, by the Application of a Composition newly’
invented by Mr. Charles Wilson, of Worcester Street, near Union Hall, in.
the Borough - - - - eer 141-
Vil. Experiments on the Effects produced by a High Temperature on the Ani-
» mal Economy. By F. F. Delaroche, of Geneva 142
VIII. On the Increase of Temperature produced by the Galvanic Action. By
Mr. John Tatum, Jun. = : - - 149
"Accidents in the Channel
‘
Scientific News.—On the Tempest of Feb. 18, which produced many dreadful
kg = i af oy ae
JUFLY,
a CONTENTS.
JULY, 1807.
Engravings of the following Objects: 1, Theory.of Looming or Horizontal Re-
fraction. 2. Mr. Salmon’s Specimens of good and bad Pruning of Fir Trees.
I. On Looming, or Horizontal Refraction. By a Correspondent’ =" 153!
II. Remarks on Pruning Fir Trees; with an Engraving, to explain the Advan-
tages of the Method recommended. By Mr. Robert Salmon, of Woburn,
Bedfordshire - - - = - 157
Ill. Abstract of a Memoir read at the Meeting of the fifth Class of the Institute,
September 29th, 1806, by Mr. Laplace, on the apparent Attraction and Re-
pulsion of small Bodies floating on the Surface of Liquids. -, .., 164
IV. Abstract of a Memoir on the Adhesion of Bodies to the Surface of Fluids,
read \at the Sitting of the first Class of the Institute, Nov. the 24th, 1806.
By Mr. Laplace - . rate 169
Y. Account of a Loom to be worked by Steam or Water. By Mr. John Austin,.
of Glasgow - - - - emi oe A
VI. Observations and Experiments respecting the Art of making Copies of Writ-
ten Paper by Pressure. ByR.T. . - - > Pe Me Wate aa Yo
VII. Of Violet Purple, and the different Tints that may be derived from it. By
John Michael Haussman - 182
‘Vili. On Cast Iron. By Professor Proust - - 185
1X. On Filtering Stones, and the Method of determining the specific, Gravity
of Substances with large Pores. By Mr. Guyton = - - 190
X. Report ona sculptured Head of Flint, with a Covering of Calcedony, made
to the Physical and Mathematical Class of the Institute, March 31, 1806.
By Mr. Guyton - - - arr ——e 195
XI. Experiments on Double Vision. By Dr. Haldat, Secretary to the Academy
of Nancy - - - ~ phe cs . 201
XII. Experiments on the Effects produced by a high Temperature on the Ani-
mal Economy. By F. F. Delaroche, of Geneva 215
XIII. Observations on the Two different Methods of preparing Acetic Ether.
_ By Mr. Henry, Professor in the School of Pharmacy at Paris - 219
XIV. Inquiries concerning the Oxidations of Iron. By Mr. Darso 221,
XV. Scientific News - > - - 227
AUGUST,
CONTENTS. vil
‘AUGUST, 1807.
Evgravin 8 of the following ‘Objects: +i. Mr. Field’s ‘Stove for Heating or Dry-
_ ing. oy Mr. Waistell’s Horse Hoe. 3. Mr. Curwen’s Weed Harrow.
TAs serpin: ¢ on two new Classes of Galvanic Gandacters. by Mr. eae
) “ Page 233
IL. ‘Facts eaaaid a History of Prussates By Mr. Proust - 249
Tl. ‘An Account df a Stove for Heation Rooms, or Drying different Aiticles.
ei Mr. G. Field, of Newman Street — - . - 263
W. nguities concerning the Oxidations of Iron. By Mr. Darso e _ 267
'”, , Account of Mr.Curwen’'s Drill Horse Hoe, or Weed Harrow tat 281
WI. Account of a’ Drill Horse Hoe for hehe a communicated by Mr.. Charles
© Waistell © - = 284
WII. On Capillary Action. By Mr. Laplace Sate oRgansd MD ae
Vit. Letter from Mr. Delaville, M.D. of Cherbourg, to Mr. Vauquelin,
‘Member of the Tnstitte, on the Oxidation of Metals, and particularly on that
‘-ef Lead - - - - 297
‘WX An Essay on Instinct, ise to ihe French National Institute. By Mr. Dupont
~*de Nemours 229
XK. Observations on the Sulphurous Acid. By Mr. Planche. Read to the Soci-
“ety of Pharmacy, November the 15th, 1806 "= = 303
ee Scientific News’: ‘French National Institute ~ + di race 306
ban
SUPPLEMENT
viii CONTENTS
SUPPLEMENT TO VOL. XVII.
Engravings of the following Objects: 1. Apparatus for triturating Quicksilver:
e yes 4 s New Classes of Galvanic Conductors: 3. Mr, J. Trotter's Curyili-
near Saw: 4. Mr. J. Hardie’s Bookbinder’s Cutting Press.
J. Description of a Machine for triturating ae combining Quicksilver with c other
Substances. By a Correspondent - 313
Wf. A Memoir on Two new Classes of Galvanic Conductors. By Mr. Erman
’ 316
Il. Inquiries concerning the Oxidations of Iron. By Mr. Darso 328
IV. Description of a Curvilinear Saw, pee by John Ben, Esq., of Soho
Square - > > 334
V. Actount of a Bookbinder’s Cutting Press, for which Fifteen Guineas were
/ yoted to Mr. James Hardie, of Glasgow, by the Society of Arts sic (336
VI, On Blende, and same other Articles. By Professor Proust, issn BOF
VIt. Remarks on the Structure of Mount Juray from a considerable Number of
Heights taken by the Barometer, and extended through France to the Sea.
By Mr. And, de Gy, Member of the Academy of. Cassel, &c. 341
VIII. Some Mineralogical and Geological Obseneaane, made in the Isle of
Arran. By the Rev. James Headrick - * S44
FX. Questigns respecting the Vines and: Wines of Champagne, tine Mr. “ee
_ with Answers to them | by Mr, Gernen, of Epernay { Yo
X...On the most sensible Reagents for Muriatic, Carbonic, and Sulphuric ern
and for Ammonia. By C. H. Pfaff, Professor of Chemistry at Kiel. 360
XI. Some farther Remarks on the pretended Formation of Muriatic Acid in
Water by the Influence of the Galvanic Pile. By thesame - 7362
XP. Description of the Mode of making Threshing-Floors in the Commune of
Valbonnais, in the Department of the Isere. By Mr. J. J. Champollion Fi _
Seeretary to the Society of Sciences and Arts at Grenoble, &c. 363
XII. Scientific News—French National Institute - . 365
4
A
JOURNAL
NATURAL PHILOSOPHY; CHEMISTRY
AND
THE ARTS,
JUNE, 1807.
ARTICLE I.
Description of the Camera Lucida. By W.U. Wouraston,
Sec. R.S.
Havine a short time since amused myself with attempts New instt-
to sketch various interesting views, without an adequate ment for de
knowledge of the art of drawing, my mind was naturally
employed in facilitating the means of transferring to paper
the apparent relative positions of the objects before me;
and I am in hopes that the instrument, which I contrived
for this purpose, may be acceptable even to those who
have attained to greater proficiency in the art, on ac-
count of the many advantages it possesses over the Camera
Obscura.
The principles on which it is constructed will probably Principles.
be most distinctly explained by tracing the successive steps,
by which I proceeded in its formation.
While [look directly down ata sheet of paper on-my Objects seen as
table, if I hold between my eye and the paper a piece of cee ee
plain glass, inclined from me downwards at an angle of flection from
45°, Isee by reflection the view that is before me, in the at
same direction that I see my paper through the glass. I
might then take a sketch of it; but the position of the ob-
jects: would be reversed.
To obtain a direct view, it is necessary to haye two res By asingle ree
Vor. XVII.—Jung, 1807. B flections, “ection
are inverted;
=
9
f
two refiectious
give the natural
Position,
The objects
and the paper
cannot be dis-
tinctly seen at
once,
Arrangement
of the glasses.
Another con-
struction.
Difference in
the latter in-
CAMERA LUCIDA.
flections. The transparent glass must for this purpose be
inclined to the perpendicular line of sight only the half of
45°, that it may reflect the view a second time from a piece
of mae glass placed beneath it, and inclined upwards af
an equal angle. The objects now appear as if seen through
the paper in the same place as before; but they are ditect
instead of being inverted, and they may be discerned in this
manner sufficiently well’ for determining the principal
positions.
The pencil, however, and any object, which it is to
trace, cannot both be seen distinctly in the same state of
the cye, on account of the difference of their distances,
and the efforts of successive adaption of the eye to one or
to the other, would become painful if frequently repeated.
In order to remedy this inconvenience, the paper and pen-
cil may be viewed through a convex lens of such a focus,
as to require no more effort than is necessary for secing
the distant objects distinctly. . These will then ap-
pear to correspond with the paper in distance as well as
direction, and may be drawn with facility, aa with any
desired degree of precision.
This arrangement of glasses will probably be best under.
stood from inspection of Fig. I. a 6 in the transparent glass ;
b ¢ the lower reflector; 5 da convex lens (of twelve inches
inches focus) e the position of the eye; and f ghe the
course of the rays. See Pl. I.
In some cases a different construction will be preferable.
Those eyes, which without assistance are adapted to seeing
near objects alone, will not admit the use of a convex glass ;
but will on the contrary require one that is concave to be.
placed in front, to render the distant objects distinct. The
frame for a glass of this construction is represented at é k,
(fig 3.) turning upon the same hinge at A with a convex
glass in the frame 1 m, and moving in such a manner, that
either of the glasses may be turned alone into its place, as
may be necessary to suit an eye that is long or short sighted.
Those persons, however, whose sight is nearly perfect,
may at pleasure use either of the glasses.
The instrument represented in that figure differs moreover
in other respects from the foregoing, which I have chosen
5 ie ta
CAMERA LUCIDAs 3:
to describe first, because the action of the reflectors there strumént.
employed would be more generally understood. But those apts eg
who are conversant with the science of optics will perceive
the advantage that may be derived in this instance from pris<
matic reflection; for when a ray of light has entered a Solid _
piece of glass, and falls from within upon any surface, at
an inclination of only twenty-two or twenty-three degrees,
as above supposed, the refractive power of the glass is such
as to suffer none of that light to pass out, and the surface
becomes in this case the most brilliant reflector that can be
employed.
Fig. 2. represents the section of a solid prismatic piece of Figure of the
glass, within which both the reflections requisite are effected P™!S™-
at the surfaces a 6, bc, in such a manner that the ray f g,
after being reflected firstat g, andagain ath, arrives at the
eye in a direction h e at right angles to f g.
There is another circumstance in this construction neces- Remedy for
sary to be attended to, and which remains to be explained. aicceet. of
Where the refleetion was produced by a piece of plain glass, direct light
it is obvious that any objects behind the glass (if sufficiently | ote -
illuminated) might be seen through the glass as well”
as the reflected image. But when the prismatic reflector is
employed, since no light can be transmitted directly through
it, the eye must be so placed that only a part of its pupil
may be intercepted by the edge of the prism, as at e Fig. 2.
The distant ebjects will then be seen by this portion of the
eye, while the paper and pencil are scen past the edge of
the prism by the remainder of the pupil.
In order to avoid inconvenience that might arise from
unintentional motion of the eye, the relative quantities of
light to be received from the object, and from the paper
are regulated by a small hole in a piece of hrass, which by
moving on a center at c, fig. 3. is capable of adjustment to
every inequality of light that is likely to occur. :
Since the size of the whole instrument, from being so near The instruinent
the eye, does not require to. be large, i have on -many ac. is of small di-
counts preferred the smallest size that could be executed: “ani
with correctness, and have had. it constructed on such a
scale, that the lenses are only 2 of an inch in diameter. |
Though the original design, and principal use of this in-It may be iised
in copyifig
B2 strument 4.4 wings.
nstructions, |
It answers
every purpose
of the penta-
graph.
Method of
using the in-
strument for
this purpose.
Magnified de-
signs.
CAMERA LUCIDA.
strument is to facilitate the delineation of objects in trué
perspective, yet this is by no means the sole purpose to
which it is adapted; for the same arrangement of reflectors
may be employed with equal advantage for copying what
has been already drawn, and may thus assist a learner in
acquiring at least a correct outline of any subject.
For this purpose the drawing to be copied should be
placed as nearly as may be at the same distance before the
instrument that the paper is beneath the eye-hole, for in
that case the size will be the same, and no lens will be ne-
cessary either to the object, or to the pencil.
By a proper use of the same instrument, every purpose
of the pentagraph may also be answered, as a painting may
be reduced in any proportion required, by placing it at a
distance in due proportion greater than that of the paper
from the instrument. In this case a lens becomes requisite
for enabling the eye to see at two unequal distances with
equal distinctness, and in order that one lens may suit for
all these purposes, there is an advantage in carrying the
height of the stand according to the proportion in which
the reduction is to be effected.
The principles on which the height of the stem is adjusted
will be readily understood by those who are accustomed to |
optical considerations. For as in taking a perspective
view the rays from the paper are rendered parallel, by
placing a lens at the distance of its préncipal focus from the
paper, because the rays received from the ‘distant objects
are parallel; so also when the object seen by reflection is
at so short a distance that the rays received from it are in a
certain degree divergent, the rays from the paper should be
made to have the same degree of divergency in order that
the paper may be seen distinctly by the same eye; and for
this purpose the Iens must be placed at a distance less than
its principal focus. The stem of the instrument is ac-
cordingly marked at certain distances. to which the con-
jugate foci are in the several proportions of 2, 3, 4, &c.
to 1, so that distinet vision may be obtained in all cases, by’
placing the painting proportionally more distant.
By transposing the convex lens to the front of the in-
strument and reversing the proportional distances, the artist
might also enlarge his smaller sketches with every desirable
degree
NFW BOILER. 5
degree of correctness, and the naturalist might delineate
minute objects in any degree magnified.
Since the primary intention of this instrument is already,
in some measure, answered by the Camera Obscura, a com-
parison will naturally be made between them.
The objections to the Camera Obscura are
Ist. That it is too large to be carried about with con- Comparison
ni of the camera
‘ie egal lucida with the
The Camera lucida is as small and portable as ¢an be camera ob-
wished. a
2dly. In the former, all objects that are not situated
near the centre of view are more or less distorted.
‘In this, there is no distortion; so that every line, even
the most remote from the centre of sik alt is as strait as
those through the centre.
3dly. In -that, the field of view does not extend beyond
302 or at most 35° with distinctness.
But in the Camera Lucida as much as 70° or 80° might be
included in one view.
As it has been thought advisable to secure an eualiiaiee
sale of this instrument by patent, those who are desirous of
purchasing it are informed that Mr. Newman (No. 24 Soho
Square) has at present the disposal of it.
II.
Description of anew Boiler constructed with a View to the
saving of Fuel. By Bensamin Count or Rumrorp.
Read at a Meeting of the first Class of the National In.
stitute the 6th October, 1806*.
Gy is well known that much is gained in the saving of fuel, Boiler for
when an extensive surface is given to that part of the tiditos Saenger e
against which the flame strikes, but this advantage is often its botedns _
counterbalanced by great inconveniences. Fora boiler of oe in
the form usually employed, having the bottom very much —
extended in proportion to its capacity, must necessarily
present a great surface to the atmosphere, and the loss of
heat, occasioned by the cold air coming in contact with
* Translated by W. Caddel Esq. and revised by the count,
from whom it was received.
this
6
Boiler for
generating
steam; having
NEW BOILER.
this surface, may be more than sufficient to compensate the
advantage derived from the extended surface of the bottom.
its bottom ter- And where the boiler is employed for producing steam, as
minating in
tubes.
it is indispensably necessary that it should be of a thickness
sufficient to resist the expansive force of the steam, it is
evident, that if the diameter be augmented (with a view to
increase the surface of the bottom) a considerable expence
is incurred on account of the additional strength that must
be given to the sides.
Having been engaged in the year 1796, ina set of ex.
periments, in which I employed the steam of boiling water
as a vehicle of heat; I had a boiler made for this purpose,
‘on a new construction, which answered well, and ever
beyond my expectations; and, as this boiler might be used
with advantage in many cases, even where it is only re.
quired to heat liquids in an open boiler, this, and another
motiye, which it would be useless to mention in this place,
have lately induced me to construct one here (at Paris) and,
to present it to the Institute.
The object chiefly had in view in the construction of this
boiler, was to give it such a form, that the surface exposed
to the fire should be great in comparison with its diameter
and capacity; and this without having a great surface ex,
posed to the cold air of the atmosphere.
The body of the boiler is in the shape of adrum. It is
a vertical cylinder of copper twelve inches in diameter, and
twelve inches high, closed at top and at bottom by circular
plates.
In the centre of the upper plate there is a cylindrical
neck six inches in diameter, and three inches high, shut at
top by a plate of copper three inches in diameter and three
Jines in thickness, fastened down by screws. :
This last plate is pierced by three holes, each about five
Jines in diameter. The first, which is in the center of the
plate, receives a vertical tube, which conveys water to the
hoiler from a reservoir which is placed above. This tube,
which descends in the inside of the boiler, to within an
jnch above the circular plate which forms its bottom, has
a cock near its lower cnd, This cock is alternately opened
and
NEW BOILER. 7
and shut, by means of a floater which swims on the surface Boiler for gene-
of the water contained in the body of the boiler. - bavite
The second of the holes in the plate that closes the neck bottom termi-
of the boiler, receives the lower end of another vertical nating in tubes.
tube, which serves to convey the steam from the boiler to
the place where it is to be used.
The third hole is occupied by a safety valve.
This description shews that there is nothing new in the
construction or arrangement of the upper part of this
boiler. In its lower part there is a contrivance for in-
creasing its surface, which has been found very useful.
The flat circular bottom of the body of the boiler, which
as I said before is twelve inches in diameter, being pierced
by seven holes, each three inches in diameter, seven cy-
lindrical tubes of thin sheet copper, three inches in diameter,
and nine inches long, closed below by circular plates, are
fixed in these holes, and firmly rivetted, and then soldered
to the flat bottom of the boiler. |
On opening the communication between the boiler and
its reservoir, the water first fills the seven tubes, and then
rises to the cylindrical body of the boiler; but it can never
rise above six inches in the body of the boiler, for when it
has got to that height, the floater is lifted to the height
necessary for shutting the cock that admits the water.
When the height of the water in the boiler is diminished
a few lines by the evaporation, the floater descends a little,
the cock is again opened, and the water flows in again
from the reservoir.
As the seven tubes that descend from the flat bottom of
the body of this boiler into the fire place, are surrounded
on all sides by the flame, the liquid contained in the boiler
is heated, and made to boil in a short time, and with the
consumption of a relatively small quantity of fuel; and
when the vertical sides of the body of the boiler, and its
upper part are suitably enveloped, in order to prevent the
loss of heat by these surfaces, this apparatus may be em.
ployed with much advantage in all cases where it.is required
to boil water for procuring steam.
And as in the case where the boiler is constructed on a
great scale, the seven tubes that descend from the bottom
of
s
NEW BOILER.
Boiler for gene- of the boiler into the fire may be made of cast iron, whilst
Yating steam ;
having its
battom ter-
minating in
tubes.
the body of the boiler is composed of shect iron, or sheet
copper; it is certain that a boiler of this kind, sufficiently
Jarge for a steam engine, a dying house, or a spirit dis-
tillery, would cost much less than a boiler of the usual
form, of equal surface and power.
But in all cases where it is required ta produce a great
quantity of steam, it will be always preferable to employ ,
several boilers of a midling size, placed beside each other,
and heated each bya separate fire, instead of using one
large boiler heated by one fire.
I have shewn, in my sixth essay, on the management of
fire, and the ceconomy of fuel, that beyond a certain limit,
there is no advantage derived from augmenting the capacity
of a boiler,
It will be perceived, that the boiler which I have the
honour of presenting to this Society, is of a form fit for
being placed in a portative furnace, and it was actually in-
tended for that purpose.
Its furnace, which is made of bricks, with a circular
iron grate of six inches in diameter, is built in the inside
of a cylinder of sheet iron, seventeen inches in diameter,
and three fect high, and can be easily transported from
place to place, by two men. ;
This eylinder of sheet iron, which is divided into two
parts, in order to facilitate the construction of themasonry,
‘weighs oaly forty-six pounds. The masonry weighs about
a hundred and fifty pounds, and the boiler twenty-two
pounds,
In order to form an estimate of the advantage which the
particular form of this boiler gives it in accelerating its
heating, we may compare the extent of surface that it pre.
sents to the action of the fire, with that of the flat bottom
of a common boiler,
The diameter of the bottom of a cylindrical boiler being
twelve inches, the surface is 113.88 square inches; but
the surface of the sides of the seven tubes that descend
from the flat bottom of our boiler (which is likewise twelve
juches in diameter) is 593.76 square inches. Therefore,
the new boiler has a surface exposed to the direct action of -
the
NEW BOILER. g
the fire, moro than five times greater than that of a boiler Roiter for gene-
of equal diameter, and of the ordinary form: how much saree a
go
‘this difference must affect the celerity of heating is easy to bottom termi-
conceive. lating in tubes.
In the manner in which boilers are usually set, their
vertical ‘sides are but little struck by the flame, and on that
account, I have not taken the effect of the sides into con-
sideration in my estimate; but even taking them into ac-
count, the new boiler will always have a surface exposed
to the fire, at least twice as great as that of a common cy-
lindrical boiler of the same diameter, as oan easily be
shewn,.
The new boiler being twelve inches in diameter, and
twelve inches high, and each of its seven tubes being three
inches in diameter, and nine inches high, its surface is
1160.44 square inches, without reckoning the circular
plate that closes its top, nor its neck.
The surface of the bottom and sides of a cylindrical
boiler of twelve inches in diameter, and twelve inches
high, will be 566.68 square inches.
_As the quantity of heat that enters a boiler in a given
time, is in proportion to the extent of surface that the
boiler presents to the fire, it is evident, that other circum-
stances being the same, a boiler with tubes descending from
its bottom, will be heated at least twice as soon as a cy-
lindrical boiler of the same diameter, witha flat bottom.
In order that a cylindrical boiler with flat bottom, sur-
rounded by flame on all sides, might have the same extent
of surface exposed ta the fire as a boiler with tubes, it
would be necessary to give it a diameter greater than that
of the boiler with tubes in the proportion of the square
root of 1160.44, to the square root of 566.68, that is, of
17.171 to 12.
Therefore, in order that a cylindrical boiler with a flat
bottom, might have the same extent of surface exposed to
the fire as our boiler with tubes, of twelve inches in dia-
meter, it would be necessary to give it a diameter of
17.171 inches.
But: if the diameter of a boiler intended for producing
steam be increased, it is necessary, at the same time, to
jncrease its thickness, in order to increase its strength.
The
10
Boiler for gene-
- yating steam 35
havtng its
bottom termi-
nating in tubes,
SOAP. BOILING,
The necessary increase of thickness, and the expence
that it will occasion, can be easily calculated.
The effort that an elastic fluid exerts against the sides of
the containing vessel, is in proportion to the surface of a
longitudinal and central section of the vessel, and con-
“sequently in proportion to the square of its diameter, the
Experiment
shewing the
advantage of
form remaining the same. Hence we may conclude, that
a steam boiler of a cylindrical form with a flat bottom,
which has the same extent of surface exposed to the fire as
a boiler of twelve inches in diameter with tubes, should be
at least twice as thick as this last, in order to have an equal
degree of strength for resisting the expansive power of the
steam.
The boiler which I have the honour of presenting to the
Society, is particularly intended to serve as a steam boiler,
but it may undoubtedly be applied to other purposes.
Having shewn it to M. Auzilly, son of a considerable soap
manufacturer of Marseilles, he thought that it might be
employed with advantage in the making of soap; and from
what he told me of the process, and of the boilers em-
ployed in that art, I am persuaded that the experiment
would succeed perfectly.
But after all, it remains to be determined, whether it
would not be still more advantageous to employ steam as a
vehicle of heat in the making of soap, instead of lighting
the fire under the bottom of the vessel in which the soap is
made. _ |
The result of an experiment which we are to make, M.
Auzilly and myself, will probably throw some art upon
this question.
Ill.
Notice of an Experiment on the Use of the Heat of Steam,
in Place of that of an open Fire, in the making of Soap,
By Bexsamin Count or Rumrorp. Read at a Meet-
ing of the First Class of the National Institute, the 20th
of October, 1806. wy
I {AD the honour of announcing to this assembly, at the
last meeting but one, that M. Auzilly and myself, were to
make
SOAP BOILING. il
make an experiment on the use of steam in the making of ae
soap. This experiment we haye made, and with perfgct i
success.
I have the honour to lay before the Society, a piece of
soap of about ten cubic inches, made in my laboratory by
this new process, which required only six hours of boiling,
whereas sixty hours and more are necessary in the ordinary
method of making soap.
From all the appearances that we observed in the course
_of this experiment, and from its results, we think ourselves
authorised to conclude, that this new method of making
soap cannot fail to be advantageous in every respect, and
that it will soon be generally adopted.
We propose to repeat the experiment on a larger scale,
as soon as we shall be able to procure the necessary utensils,
and we beg the Society to appoint commissioners ta be
present during its execution.
As I intend to communicate to the Institute, upon a
future occasion, all the details of our experiment, with an
account of the apparatus we employed in it, I shall for the
present make only one observation on the probable cause
of the acceleration of the formation of soap, which we
observed. I believe that this acceleration is due, in great
measure, if not entirely, to a motion of a peculiar kind
in the mixture of oil and lye, occasioned by the sudden
condensation of the steam introduced into the liquor. It is
a sharp stroke, like that of a hammer, which made the
whole apparatus tremble.
These strokes, which succeeded rapidly in certain cir-
cumstances, and which were violent enough to be heard at
a considerable distance, must necessarily have forced the
particles of oil and alkali to approach each other, and con-
sequently to unite.
As the violence of these strokes diminished greatly as
soon as the liquid had aequired nearly the temperature of
the steam, I propose to supply this defect by a particular
arrangement of the apparatus in the experiment we are
going to make. TI shall divide the vessel into two parts,
bya horizontal diaphragm of thin sheet copper, and causing
@ slow current of cold water to pass throug gh the lower.
division ©
1g ELECTRICAL EXPERIMENTS.
division or compartment of the vessel, I shall introduce
steam into it, through a particular tube destined for that
purpose, as soon as the mixture of oil and alkali which oc-
cupies the upper division of the vessel is become too hot for
condensing the steam.
The steam which enters the water (always kept cold) that
fills the lower compartment of the vessel, will be condensed
suddenly, and the sharp strokes which result will be com-
municated through the thin diaphragm to the hot liquid con-
tained in the upper division of the vessel, and will, I ex-
pect, accelcrate the union of the oil with the alkali. I
‘shall then shut almost entirely the cock which admits steam
into the upper division of the vessel, in order to prevent an
useless consumption of steam and heat.
I shall not: fail to give an account of the results of this
yew experiment to this assembly; and I shall rejoice if by
any researches I shall be so happy as to contribute to the
iaprovement of an art which is undoubtedly of great im.
portance to society.
IV.
On the Habitudes of Saline Bodies with Regard to Electri-
city. By Mr. Wru11aM Sxrimsnire, Jun. Communi.
eated by Mr. Cutupertson,
Dear Sir,
Havine made some further progress in my electrical}
experiments, J take the liberty of sending you the results,
in order, if youthink proper, for insertion in Mr. Nichol-
son’s valuable Journal.
Wn. SKRIMSHIRE, Jun.
To Mr. Curusertson.
. - Saline Substances.
Causes of error “WHEN the spark is taken from saline substances placed
saga upon the.conductor, there is some difficulty in ascertaining,
line crystals. | whether the spark proceeds from the salt itself, or from the
conductor, through the substance, or along the surface of
the salt, A large crystal will sometimes appear to give a
very
ELECTRICAL EXPERIMENTS: 13
very brilliant spark ramified upon its surface; but if these
ramifications be minutely examined, they will be found to
proceed from the conductor, and running up the sides of
the crystal converge to a point under the knob of the dis-
charger.
_ Whenever it is doubtful whether a crystal affords a spark Remedies, &c.
or not, I place a second crystal.upon the first, and then ap-
ply the discharger to the uppermost, when in. general,
merely a hissing stream of electric light, or at most, a small
hissing spark is perceived. Again, if the crystal be thin,
it will appear to give as good a spark as any metal, and in
truth the spark really proceeds from the conductor, and
passing through the salt renders it transparent, or rather
semi-transparent. A thin cake of agglutinated crystals al.
lows the spark to pass through its interstices with the same
appearance. It is necessary here to remark, with respect
to passing the shock through saline substances, that if the
salt be crystallized in large lumps like alum or borax, it is
shivered in pieces by the shock; and the same happens when
the lump consists of a congeries of regular crystals; but if
the shock (meaning the shock which I constantly employ in
these experiments, and which is never more than that from
a quart phial) be passed through a single crystal, no such
effect occurs, for the crystal remains perfectly whole, and is
generally rendered luminous throughout, should the salt
prove phosphoric by the electric light.
Alkalies and their Compounds.
Sub-carbonate of potash. Ist. Pearl ash gives a dense Alkali and ale
‘purple stream of electric light, instead of a spark, and is Kaline salts.
_ extremely phosphoric by the shock, its light continuing some
minutes. 2nd. Salt of tartar is very luminous, and its par-
ticles are easily scattered by the shock, when the points of
the dischargers are in contact with it.
Super-carbonate of potash in small crystals is luminous,
and scattered about, if the rods touchit; in larger crystalp
it is also luminous, but they are not fractured by passing
the shock through them.*
* I am inclined to suspect that the shock does not pass through,
but over the surface of a single crystal, ifit be a small crystal.
Sulphate.
14
Alkali and al-
saline salts.
ELECTRICAL EXPERIMENTS.
Sulphate of potash affords a small spark, and is luminous?
by the shock.
Nitrate of potash, commonly called nitre or salt-petrey
affords a spark which is beautifully flame-coloured on its.
surface; it is also luminous, but its light is of short dus
ration.
Muriate of potash is much more phosphorescent thar
nitre, and its light is of longer continuance.
Hyper-oxymuriate of potash is lumious, but does not ex«
plode when the shock is passed through it.
Acidulous oxalate of potash is luminous by the electric
shock.
’ Acidulous tartrite of potash. Red and white argol, and
purified crystallized cream of tartar afford similar results,
except that cream of tartar is rather more luminous than
the others. They do not give a spark; but a cake of cons
glomerated crystals allows a spark to pass through it, ren«
dering it almost transparent.
Neutral tartrite of potash, or soluble tartar of the apo-
theearies, is rendered luminous by the explosion. _
Tartrite of potash and soda, or Rochelle salt of the apo.
thecaries, affords a beautiful spark, flame coloured, and
ramified upon the surface, when a single crystal is made use
of; but when one crystal is placed upon another, and the
discharger applied to the uppermost, only a purple hissing
stream or a very slight spark can be taken fromit. It is
luminous when the shock is passed above its surface.
' Acetite of potash gives a purple spark, flame coloured
and ramified on its surface, even when one crystal is placed
upon another. It is rendered luminous merely by taking
the spark from the conductor near it; and by exposure to
the sheck it is beautifully phosphorescent, shining with a
green light, and is even superior in brilliancy to the sulphu-
ret-of lime, though its light is of shorter duration than in
that ‘preparation. This salt is extremely deliquescent, in.
which state, and even when quite dissolved, it is still ren.
dered luminous by exposure to the light of the explosion.
Soda. Sub-carbonate of soda affords a hissing purple
spark, flame coloured on its surface. It is phosphorescent
by the shock, 3
Sulphate
: A»
ELECTRICAL EXPERIMENTS. 1s
Sulphate of soda gives a purple spark, and is luminous Alkali and al
. ; kaline salts.
by the shock.
Nitrate of soda is not at all luminous, even -when the
points of the discharging rods are in contact with it, during
the explosion.
Muriate of soda. Several native specimens of different
colours were tried, and gave only a small stream of electric
light, almost without any sound. They were all luminous
by the shock, as was also common culinary salt. ,
Phosphate of soda affords only a purple hissing stream,
but is Inminous by the shock, though in a less degree than
the sub-carbonate.
Sub-borate of soda. ist. Tincal gives a purple hissing
spark, apparently proceeding froma red point upon its sur-
face. Itis but slightly luminous by the shock. 2nd. Fast
Indian borax gives nospark, but the clectric fluid glides si -
Jently over every part of its surface from the conductor to
the knob of the discharger. Its phosphorescency by the
shock is superior to tincal, but not equal to the refined bo-
rax of theshops. 3rd. Refined borax affords a hissing pur-
ple spark, sometimes flame coloured upon its surface; but
when a large piece is placed on the conductor itallows only
a purple stream to be drawn from it. It is luminous when
Athe explosion is made adoze it, but when the shock is passed
throughit, the phosphoric appearance is very brilliant and
has a greenish tint, the light is of short continuance, and
the salt is shattered to picces.
Ammonia. Aqua ammoniz of the shops is not luminous.
Carbonate of ammonia affords a dense purple spark, ra-
diated on its surface. It is yery luminous with a white light,
when the shock is taken above it; but it possesses a delicate
blue or rather purple tint, when the rods rest upon its sure
face, and itis shattered into luminous pieces when the shock
is passed through it.
Sulphate of ammonia cives a purple hissing stream and is ‘
luminous by the shock.
Nitrate of ammonia is not at all luminous when properly
prepared and crystallized ; butit is slightly phosphoric when
prepared with the common aqua fortis of the shops, and
not carefully crystallized.
; Muriate
16
Acids.
Metallic salts.
ELECTRICAL EXPERIMENTS:
Muriate 6f ammonia affords a purple spark, and is lumis
nous by the explosion. 2a?
Succinate of ammonia is luthinovs when the shock is passed
above it, and is readily dispersed in luminous particles when
the rods are placed in contact with it.
Acids.
Sulphuric, nitric, muriatic, phosphoric and acetous acids
are not luminous. —
Nitric acid affords only a hissing stream instead of a spark.
It is extremely phosphorescent with the explosion made
above it, shining with a greenish light; and when the shock
is passed through a lump of crystals it is fractured into nu-
merous phosphoric pieces. It is rendered luminous merely:
by taking sparks from the conductor in its vicihity.
Boracic acid is next in phosphorescency to the citric.
Benzoic acid is almost equaliy luminous with the boracic.
Tartaric acid affords a hissing stream instead of a spark.
It is luminous by the shock, but not quite so phosphoric as
“the benzoic acid.
Oxalic acid is also luminous by the explosion, but less so
than any of the crystallizable acids here mentioned.
Arsenious acid gives no spark, but allows the fluid to pass
freely over its surface from the conductor to a considerable
distance, giving the sensation of a shock when held in the
hand; but when placed upon the conductor and the knob
of the discharger rests upon its surface, the spark procecds
from the conductor to the discharger, through the substance
of the acid, rendering it semi-transparent. It is very phos«
phorescent with a white light, when the explosion is made
above its surface; hut when the points of the rods rest upom
it, the light is yellow tinged with green.
Metallic Salts.
Nitrate of silver, commonly called lunar eaustic, does
not give a spark, neither is it luminous by the electric light.
Sulphate of mercury, called turpeth mineral, and white
crystallized nitrate of mercury are not luminous.
Howard’s fulminating mercury is not phosphorescent by
passing the shock above it; but when a grain or two of this
: salt
ELECTRICAL EXPERIMENTS. fe We
eA
salt are placed in the track of -the discharge between the Metallic salts.
points of the rods it explodes witha slight shock, The ex.
plesion is accompanied with a dark red or crimson coloured
flame and slight detonation, it is a very pleasing experi
ment, and when exploded upon a plate of glass the mercury
is revived, and silvers the plate like amirror, but it is easily
effaced. Wher exploded upon card, a coloured stain is proe
- duced, which is indelible.
-Muriate of mercury, called calomel, is not luminous.
Oxymuriate of mercury, or corrosive sublimate of mere
cury, affords only a purple stream on its fracture, but the
_smooth convex surface which has formerly been attached to
the vessel it was sublimed in gives a fine purple spark, of a
beautiful bright green colour onitssurface. It is very phos-
_phorescent. by passing the shock above it. Great caution is
required in making experiments with this substance, as elec.
tricity detaches from jt, and throws into the atmosphere,
innumerable minute and invisible particles of this caustic
Poisonous salt, which produce inflammation of the men-
brane lining the nose, and a very disagreeable sensation in
the mouth and fauces, attended with a slight salivation.—
‘Similar effects occur during the explosion of the fulminating
mercury, if frequently repeated.
Sulphate, nitrate, and phosphate of copper are 2 not lu.
minous, neither do they give any spark.
Acetite of copper, verdigris of the shops, gives a spark
ramified upon jts surfacc, but is not luminous “A the electric
explosion. .
Carbonate or-rust of iron gives a spark, butis not lu.
minous.
Sulphate, gallate, and prussiate of iron are not luminous,
Carbonate and acetite of lead give no spark, nor are they
juminous.
Muriate of lead is slightly luminous by the explosion.
Sulphate of zinc affords a small purple stream instead of
a spark. It is not luminous when the explosion is made
above its surface, but merely in the track of the fluid when
? “the rods rest upon it, at some distance from each other.
Carbonate of zinc or calamine. Several native specimens
Vor. XVIT.—June, 1807. ® . ef
-
18
Compounds
containing
salts.
DECOMPOSITION OF LIGHT.
of this substance covering crystals of a calcareous spar, as
well as the levigated calamine of the shops, were phospho.
' pescent.
Muriate of antimony is not luminous.
Phosphate of lime and antimony, or James’s powder of
the apothecaries is very phosphorescent, its light continu-
ing for some minutes.
Tartrite of potash and antimony, or emetic tartar of the
apothecaries, is luminous, but not comparable with James’s
powder.
,
Miscellaneous Sabstances.
Soaps. —Common hard white and brown soaps afford very
good sparks, which are sometimes flame-coloured on the
surface; but they are not luminous even in the track of the
fluid upon their surfaces. Neither is the common soft soap
at all luminous. ia r
- Sulphuret of potash gives a purple hissing stream, and is
not luminous, in which it oy differs from ie sulphuret
of lime. se
Common fulminating powder is not luminous, neither
does it explode with the shock which I employ in these ex-
periments,
Gun powder is not rendered luminous by the electric
light, nor dees explode with a small shock.
In my first letter correct—Vol. XV. p. 281, 1. 7 from
bottom, after surface, insert and lastly along its surface.—
P. 282, 1. 3. from bottom, for sulphate rv. sulphuret.
V.
On the Decomposition of Light into it3 most simple Elements ;
a Fragment of a Work on Colours: by C. A. Prieur,
formerly Colonel in the Corps of Engineers, and Lec-
purer tn the National Institution.*
White light de- \ V TITS light is decomposed by refraction into an infi.
composed into
different co-
lours,
nite number of parts or rays. They have a different co-
* * Abridged fromthe Annales de Chimie for Sept. 1806, p. 2297.
lour
DECOMPOSITION. OF LIGHT. aio
‘lowr at every point in the length of the spectrum, » and: this
colour cannot be varied by a new refraction, if the simpli,
fication of the spectrum be at the degree to which Newton
carried.it. Though in the spectrum thus simplified the lines whichare really
of demarcation between the colours are by no means yery “stints
perceptible; it is impossible to ascribe the gradations of
their tints to one and the same law. Numerous ebserva-
tions establish the existence of several distinct species of
colours; and their division into seven classes, as given by
Newton, agrees with a great number of phenomena. Yet but not always
some substances, by-their peculiar refractive power, derange pelea at
the spaces of the colours in the spectrum; so that, for ex- though always
ample, .the green rays are in some instances brought nearer ie Che SER Of
the red, in others nearer the violet. This proves, that the
- dispersion of the rays does not depend absolutely on their
own nature. These are the principal observations it aps
peared to me necessary to make, in order to shew the pre-
sent state ef our knowledge; and I shall now proceed. to
examine the action of coloured bodies upon light.
I have formerly shewn, that all kjnds of transparent bo-~ The yellow and
dics, of different colours, which I have observed, transmit blue rays disap~-
ultimately only on the red, or green, or violet rays. The sileaa
progressive absorption never finishes by any other colours,
and I long sought in vain for a substance, in which the final
absorption should be of the yellow or blue rays.
Such a result could not fail to excite my attention. I re- okt ee ae
marked, that, under certain cireumstances, the colours @X- green and violet
hibited ‘i refraction were almost wholly these three, red, Rea betien 579
green, and violet: that sometimes yellow appeared to arise 7, Sian ene
from a mixture of red and green, and blue from a mixture compounded of
of green and violet; which my dial,* as well as the placing theers
of certain coloured glasses on each other, indicated as pos-
‘sible. JI perceived too, that the tints of the seven orders
of colours might be imitated by the three primitive colours
alone which I have mentioned.+ This was _sufficient to
suggest
* his dial is sionply a circle exhibiting the seven primitive co-
ours .conformably to the ideas of Newton. See Optics, Book I.
Prob. 2. ‘The author has explained the principles ot the construc-
tion of this dial, and its leading properties, in his work.
4 This proposition of three primitive colours is yery different from
C2 that
This hy pothe-
‘sis not iticon-
sistent with
known pheno-
Weffa.
; DECOMPOSITION OF ‘TiaHT.
bugge@st to me the idea, that perhaps these three kinds of
Yays were all that really existed; a proposition that required
to be examined with care proportioned to its importance.
Accordingly I inquired into the probabilities that might be
brought to support it, and compared it with all the pheno-
‘ehh of colour that occurred to me, and lastly I verified it
‘by direct experiments. .
The details of these I’shall reserve for the last Epcos: ae.
ginning with an account of the others.
I have already mentioned, that the snp posta. of three
colours was not inconsistent with the formation of all the
tints of the spectrum. Neither is it in contradiction with
_ the unchangeablentss of éach tint by a second refraction:
for if a red ray of a certain degree, for example, be found
in the Spectrum at the same place as a green of a certain
degree, their combination will give a yellow of a particular
tint; and as these two rays have the same refrangibility, @
similar refractive power cannot again separate them. Ac-
_cordingly, to have a spectrum in all points similar to that
Explains the
contiguity and
distinction of
the 7 colours.
‘which really occurs, nothing more is necessary than to con.
ceive it composed of three spectrums partly overlaying each
other; one formed of red rays, differently refrangible, and
of different tints; a second, trenching a little upon the first,
and having only green rays, but a similar gradation of tints
corresponding to, their refrangibility; and lastly a third,
exhibiting an analogous series of violet-rays, and in like
manner trenching upon the green. -On this hypothesis,
there will be no disruption of the whole image, whatever
extent be given to it by refraction: besides, it’accounts for
seven colours separated by lines of demarcation, which RO
‘one yet has explained.
To comprehend this, let us look at: Fig. Le PL which
is constructed in the following manner: A right. line is di.
vided into seven parts, proportioned to the spaces of the
seven colours in the spectrum, and marked by the initials
‘of those colours. Qn each of the points of division I have
“that formerly adopted ; for the red, yellow and blue, have bihseto
been so considered; while here they are the red, green, and violet,
the exclusive existence of whichis proved by ie nba of white
light in several rays, as will be seen farther on, »* * ~~
so aha
DECOMPQRITION OF GRE. 2)
erécted an ordinate, and aoveaud he the arbitrary in-
clined line ad, then 6 g cutting the former in e, and “lastly
e h cutting the preceding in f. I suppose, that the modi-
fications of the red rays, on which their different refrangi-
bility depends, are represented by the ordinates correspond.
ing to the line ad: these quantities express nothing relative
either to the velocity of the rays, or the magnitude of their
particles; perhaps they may have a relation to their density,
or to any other quality whatever that constitutes their dif,
ference. In Newton’s system of seven classes of primitite
colours, there are likewise red rays difforently refrangible ;
this therefore is nota difficulty peculiar to the state of things
I am examining. In like manner the ordinates of the line
g g will be the modifications of the green; and those of the
line kh ec the modifications of the violet. Hence itis evident,
that the first division of colours from @ to b will be red
alone; that it will be followed by a mixture or combination
of green and red from toc, in which the quantity of the
latter will predominate, and give orange; after which an-
other mixture of red and green will proceed from ¢ to d, in
which the green will predominate more and more, forming
yellow; then from d to e will be green alone; frome to f the
mixture of green and violet that produces blue; from f tog
ths mixture producing indigo; and lastly from g toh pure
violet.
But another very striking properiy of the spectrum, Accounts for
which has not hitherto been explained, is the greater bright- ee
ness of the yellow compared with the rest. This proceeds
evidently in my figure from being the sum of the light of the
redand of the green. In the blue too there is an augmen. Blue next in
-tation of light by the union of the green and violet; but ble light,
the effect is much less than in the preceding instance, both :
from the nature of those colours, and their extent, though
there is some trace of it in the spectrum when properly dis.
played.
By this figure, however, IF do nat pretend to exhibit any
thing more than what may possibly happen. For this rea-
son I have limited the ordinates of each colour by a right
‘line merely ; for as the law of their progression is notknown
so that it is impossible to give the precise curve, l have
adopted the simplest line as sufficient for my purpose.
The
22
a
Properties of
the spectrum
delineated on a
circle.
Solution of the
problem.
é
DECOMPOSITION OF LIGHT.
_ The striking agreenrent of my hypothesis with the pez
culiarities of the spectrum excited me the more to apply it
to the dial of colours. This coloured figure has such’sins
gular properties, that the mind cannot easily bend itself to
them. Hlow indeed can it conceive the existence of an infi-
nite number of luminous rays, all different yet equally sim-
ple? How is it, that taken in pairs from the extremities of
every diameter of the dial, that is from any two opposite
points, they shall always form the same white? For in-
stance, a certain red ray with a green gives white; afi
orange with a blue, the same; a violet with a yellow, still
the same. What a strange cimniteed@! Hlow again are the
seven distinct orders of the spectrum consistent with that
insensible gradation of the tints of the dial recommended
by Newton, and in fact necessary? Yet all these are so
completely supported by experiment, that their reality carts
tiot be questioned.
Thus I had a problem to solve, the complicated data of
which seemed at first not to promise asimple solution; yet,
after, various attempts, L attained my object, as will be seen.
_ First I considered, that both the nature and quantity of
the red, green, and violet rays, which I suppose to be the
sole elements of white light, are absolutely unknown. But.
I could likewise conceive them transformed into coloured
matters of such intensity, or condensation, that the mix.
ture: of an equal quanay of each sbould produce exactly |
white,
_ In the second place I drew Fig. 2. This consists of three
curves nearly circalar and alike, herb aba round the dial in
the following manner. I first des scribed three equal circles,
having their centres in the radii drawn throngh the divisions
of 60, 180, and 300 degrees; and the circumferences of
which were targents to the dial at tlie divisions of 250, 360:
and 120 degrees respectively I then sirodified each circum-
ference by this law, that, on prolonging the diameters of
the dial in every possible direction, the sum of the prolon-
gations of every diameter to the new curve should be a con-
stant quantity. It is easy to understand this second con-
struction, by which it will appear, that the resulting « curve
differs in fact little from the éircular circ ‘amference, ’
si Vs a
- DECOMPOSITION OF LIGHT. 23
Thirdly, I conceived, that all the prolongations of the
radii of the dial to the red curve represented each a pro-
portional quantity of my red matter mentioned in the para-
graph before the preceding ; so that this dial is surrounded
by a red crescent to a certain point, whence it decreases ac-
cording to a given law. We must likewise admit a green
envelop, analogous to the preceding, and limited by the
curve of that colour; and lastly a violet envelop, within
the third curve.
This supposed, if for each point of the dial we makea
mixture of colours corresponding to that point, we shall
have a series of tints inimperceptible gradation from one to
the other; which in tone, place, and every other respect,
will be extremely analogous to the colours of the dial, that
I had previously traced conformably to the ideas of Newton,
and are such, that the union of two diametrically opposite
to each other, will every where form a white identically the
same.
This is a result which I offer as a farther probability
greatly in favour of my hypothesis of three colours.
It is true, the dial constructed by the first method differs A little diffe -
a little from that by the last, as in this the purest red is ie
somewhat nearer the plaee of the orange, and the violet colours.
nearer that of the indigo. But, beside that this difference
is little in itself, it is supported by experience; for the re-
jation of colours in,general, and the progress of their ab-
sorption, appear to give some preference to the latter
method.
Still I must repeat, that the observations I have here
made are only to shew the possibility of the thing; the
qliestion can be decided only by the direct examination of
-the rays of light on the spectrum in its simplest state, and
this remains for me to give.
As few have the means of procuring this very simple Not easy to ob-
spectrum, and there is some difficulty in applying them, I ese gamle
shall enter into this subject somewhat atlarge. This con-simplicity; and
ceive to be the more necessary, as few appear to have re- Ra
peated experiments of this kind since Newton, atleast with
due precision. Treatises on optics indeed do not mention
this repetition formally, many philosophers having attempt-
ed
a DECOMPOSITION OF LIGHT.
éd it without success, and. others having. persuaded theme
sélves a little too hastily, that they had completely succeeds
-ed; as Abbe: Nollet, for instance, whose name has, beer
> quoted as an authority~
‘Tshould not myself have had-the means rs ssh wished,
but from the politeness and enlightened assistance of Mr.
Trémery; . Fortunately his study was provided with: every
thing necessary ; but I shall first briefly describe the nature
of the experiment, and the coriditions ear sraits requis
site. : mii
Nature of the The business. was to repeat the axperialaath in which
arker Newton obtained a well defined solar spectrum, the breadth
of which, by concentrating the pencil of light, was reduced
to #55 or zy of its length; and which consequently exhi-
bited the homogeneal rays incomparably more distinct from
éach other than in the common spectrum. Opt. Book Is:
Part 1. Exp. 11. ;
Conditions re- © LE have already hinted above, that the success. depends,
sel its Ist. in operating on a pencil of light that is very small be-
fore it reaches the prism ; @dly. im producing by the prism
a considerable dispersion of the coloured rays; and 3dly;
in receiving their dissected image on. a plane itis distant
from the point of the angle of dispersion...
Obstacles to it... But these three conditions are not of thetsites stiffs
cient. It is almost impracticable to attain the desired ob-
ject by their concurrence, when the rays arrive at‘first in
parallel directions; still more if they arrive diverging, as
they do. when a pencil of light is admitted through a simple
hole.in the window shutter of a dark room; in which case
the sensible diameter of the sun’s disk must occasion.a: di,
vergence of the pencil. There is only one circumstance fas
vourable therefore, that in which the rays may be rendered
convergent, without infringing the preceding conditians.
Newton’s me- _ The only method of doing this did not escape the sagacity
Pe. of Newton. . He effected it by placing at a considerable
converging the «, : : ‘
pencil by a lens distance from the shutter, and hut_a little before the prisin,
oe. rule con- alens of a long focus, which by its position regulated the
‘ distance of the plane on which the spectrum was to be res
ceived. In this way, and by the assistance of some other
pies precautions, he resolved this grand problem in optics, +
tia The
DECOMPOSITION OF LIGHT: . B&B
' The following is the mantier in which we geniaeai and
its results,
It is not easy to procure a single lens, that shall “He ca Difficulty of -
pable of giving a focus of ten or eleven feet in the position petting ages?
in -which. Newton employed it; for several glasses of little ~~
curvature, that were lent me as fit for the purpose, were
altogether incapable of effecting it. Ithen imagined, that . .
{i might succeed by placing near the shutter an object glass Resource of the
of short focus, to make the pencil very divergent beyond —
it; and placing at the same time ata sufficient distance,
an excellent lens of Mr. Tremery’s of five feet focus.
The effect answered our wishes, and in consequence we His apparatus
arranged our apparatus as follows: 1, on the outside of Weapon
_ the windows, a plaue metallic speculum, to reflect the solar
image: 2, an object glass of 87 centimetres (33 inches)
focus, distant from the speculum about 24 centimetres
(9, 36 inches): 3, a diaphragm, pierced with a hole six
millimetres in diameter (2.36 lines,) and at the distance of
11 centimetres (4.°3 inches) from the object glass, to in-
troduce the pencil of light into the room: 4, a lens of 162
centimetres (5 feet, 3 inches focus, placed 32 centimetres
(1 foot) from the object glass: 5, at 11 centimetres (4, 3
inches) from the lens a prism of very clear flint glass, with
angles ef 60°, covered with black paper on cach side, ex.
cept at the place left for the transmission of the rays; this
prism being continued so-as to be moveable in different
directions, as occasion might require: 6, a board covered
with white cloth, at the distance of 422 centimetres (13
feet, 8 inches) froin the lens. All these were placed, kept,
‘or brought into the proper directions, suited to their several
purposes, and to the course of the sun. The place too was
so contrived, as to be rendered pretty dark at pleasure.
Having taken every possible care in arranging our appa~-
ratus, we were able to obtain every day, when it was fine. <9 7°"
weather, a very simple spectrum for several hours; ei
which was quite sufficient for our various experiments, at
some of which Messrs. Berthollet, the father and son,: Mr.
song and other gentlemen were present.
» The: spectrum was very distinctly bounded by two rede, very distinet
sikinear and perfegtly parallel sides, J4s length was a iittle spectrum 9}
P inches long
more
26 DECOMPOSITION OF LIGHTs
Breadth 1-25th. more 'than 24 centimetres. (9. 36 inches) Its breadth was
xy of its length, when the aperture in the diaphragm was
6 millimetres. (2. 34 lines) Sometimes this was reduced onc
half, and the contraction of the spectrum was proportional,
the breadth then not being more than ~,; and lastly, by
diminishing the aperture, it was reduced to z'y of the length.
Colqurs bright © As to the strength of: the colours, they were, vivid and
and vivid, bright as might be expected. ‘The impression on the eye
tance it appear- W2S such; on account of the narrowness of the image, tha
ed triangular, ata few decimetres ( two thirds of a foot) from the cloth
the red forming die f dishaicedien sehity di ; f sae ds
the point. e spectrum appeared as two straight lines, forming a
smali angle, the apex of which was at the red extremity,
and the base at the violet. On going nearer it appeared a
single line. It was thesame, if the spectrum were examined
from a distance throughaglass. This doubling or radiating
of the image depends on the conformation of the eye, and
is connected with some other phenomena, of- which I may
hereafter give an account.
‘The line of dee Lhedistinction of the colours, and their separation into
marcation seven classes, was likewise one of the objects of our en-
betweenthe -_, : Pa Sos
colours not @uiry. Though the existence of this, distinction was per-
very precise. ceived, it must be confessed, that it was not easy to trace
all their divisions. I made some attempts. to effect it, the
narrative of which I shall pass over for the presents merely
observing, that Newton did not make his division on a
More so in the spectrum thus narrowed, but on.one much larger, obtained
am Fan the usual way without a lens. Opt. I, part 2, prob. I.
hie seh Lastly I shall observe, that the green colour in our spec-
shortened ; trum did not extend quite to the middle of its length, whence
the blueand it followed, that the shades between the green and red
violet lengthen- were a little shortened, and those of the blue and. violet
ed, “41 o ’ rca pp q r p ny
proportionally clongated. These effects were owing no
from the nature @oubt to the nature of the flint glass, of which our prism
of the glass. was made. We had no-opportunity of procuring common
glass free from streaks. | Having tried a hollow: prism,
formed of glasses), joined together, and. filled with water;
the faces of the glasses occasioned duplications of the spec-
trum, which rendered it confused; so that we returned to
our English flint glass; which, while perfectly: void. of
celour, combined homogeneity of substance,. and accuracy
of
DECOMPOSITION OF LIGHT: 9
of structire, with the fincst polish; in te it was to pat
appearance free from defect. 9° > “i
‘It now remains: for'me to speak of: the ie dhlubti ex~' Experiments.
periments on the analysis ‘iy ieee capi which -[shad: ssi
planned. . 9} s
. The reader may recollect, that I iis suspected the blue Hypothesis,
to be merely’ the result ofa coinbinatiers of green-and violet er Ree Ae
rays; and that in like manner the yellow’ proceeded only‘green and
from a mixture of green and red.» I reasoned then in this Marra ae
manner: on the supposition that in’ reality there existed:movgreen and red.
simple rays of blue, if we prevent the arrival of rays ro Consequences.
that part of the spectrum, either by a substance that-sufiers
only the green rays to pass, or by one that allows a passage
to the violet only, we shall find beyond:these substances
only green or violet ;. otherwise, supposing the bluc rays tor
be simple, they will traverse neither. of the’ substances 1
have mentioned, as we shall find beyond them nothing but’
black. We may reason ia a similar way with respect ‘Yo -
the yellow, which must be subjected to the trial ofa red
substance and a green. (pe
‘Thus we must be furnished with three substances Siaked Requisites for
in the requisite manner. For the violet f employed an oe tor
ammoniacal solution of copper, in a phial with plane
parallel surfaces: for the green a solution of muriat of
‘copper, in asimilar phial: and for the red, either wine of
a good colour, or a tincture of cochineal. All these must
be sufficiently concentrated, or they ‘will transmit other
rays, beside those we have in view. This concentration
has the inconvenience of rendering the colour obscure, it is
true, and this is some obstacle to their use; but it is the
only way in which nature permits us to oljéatn sre
colours, and we must be content with it. anh
Coloured glasses might be substituted for the red ant .
green liquors; but with respect’ to the violet I coer: not
procure any, on which | could depend. :
Every thing being thus prepared, I made my <iamee
in concert with Mr. Tremery and Mr. Drappier.
We had a screen, which we could place at’ will before 4 pparatus.
the cloth opposite the place of the spectrum. In this. screen
was a small cwrcular hole 2 ar millimetres (1.17 er 1156
linc)
28 DECOMPOSITION’ OF LIGHT:
linc) im dianteter, by. means of which we could allow a
smail coloured pencil to fall on the cloth, while all the rest
was dark. We could easily ascertain, that this little pencil,
taken successively from the different colours, was simplified
as much as possible by refraction; for the circular spot,
examined some distance with a prism, was not at all irregular.
- We then passed through the small hole a pencil of very
decided blue; and in this respect our latitude of choice was
great, since in our spectrum the blue had an extent of were
Blue light than 54 millimetres. (2 inches) The blue spot being well
a a formed on the cloth, the green phial was placed before the
hrough a grecn
medium was hole; when the light of the spot was immediately much
ee em, weakened, andits colour changed to green. On substituting
was violet. the violet phial in the place of the green, the spot became
violet. This experimeut was repeated several times, that
we might convince ‘ourselves of the fact, and succeeded
uniformly.
Yollowchangea ‘The trial with the yellow succeeded in like manner; it
to red and was changed successively to red and green, according to the
Breer substance opposed to the rays. :
Experiment Another day these experiments were repeated with some
varied by little alterations. When the small round image fell upon
Hpi es the cloth, we went behind to leok at it; and found that it
behind the passed through, appearing om the back of the cloth, which
sie hac acs was muslin well stiffened with starch. In this way we could
stance put make our experiments more conveniently, as we had only to
before the eye. o over our eve with a colored substance, and Took at the
Blue light, as little spot through it. When the spot was formed by blue
before. lizht, it appeared’ green, or violet, according to the sub-
stance interposed. Through a red: substance no light was,
secn: a proof, that the preceding efiect did not arise from
white light mixed with blue. If it were viewed through an
orange glass, the property of which is to absorb only the
blue and violet rays, the spot appeared green; a proof
that it was formed in reality by green and violet rays.
Yellow, the Finally the yellow spot exhibited similar appearances ;
same altogether invisible through a violet substance, it shewed
o itself green or red through substances of these colours.
Arguments for. Such are the results, that confirm my opinion of the
poe ayia elementary parts of light. Now let these he combined with
green, and . , ' the
yioiet.
53h
TT
>
‘sorts of rays. Ina smallmass, the body will first'a absorb |
BECOMPOSITION OF LIGHT, 29
the effects of absorption, which ultimately leaves only red,
green, or violet rays; with the simple and natnral explana-
tion of the principal appearances of. the Spectrum, by
means of three kinds of rays; with the happy ranner in
which these three kinds are applicable to the properties. of
the dial of colours, and remove its complication ; and I
think the whole will support my ‘proposition. {fit do not
hence appear to the natural philosopher as a fact established
beyond all question, at least he cannot refuse to consider it
as already grounded on strong probabilities, and sufficiently
interesting to merit 2 thorough investigation, which my °°
occupations have prevented me from pursuing any farther,
Recapitulation.
Thus our system of colours appears to, me. ednced to Red and green
‘these few data: three sorts of luminous ‘rays, of a parti- , ee he
green and
cular and unknown nature; red, green, and violet. Com- violet, blue.
‘bined by twos, the red and green produce yellow; ‘the pi arog
‘green and violet, blue; the violet and red, purple: the different pre--.
three together produce white; and lastly, the intermediate Pots.
‘shades are according to ihe LnsAbitonal quantities of their .
elements. ae
Bodies exercise a general action on all the rays of light, Light Peer
‘aad a particular. one relative to their peculiar nature. if >Y. refraction.
the white pencil fall obliquely on the surface of a trans.
parent body, the rays, as they penetrate it, deviate from
their original direction, some more,: others less, according
to their nature. Here we have a true analysis of white
fight, in which ‘its three simple elements may be found
‘Separate, ‘as well as combined, in different proportions,
It is thus that refraction exhibits’a series of tints, which
‘differ, in different bodies, both with respect to their general
‘deflection, measured by its mean quantity, in the relative
dispersion of the rays, ‘and in the particular position of
each’ colour.
Tf the affinity of ‘the*body for the rays of light, be aed, Bodies coloured
as to absorb some into its own substance, it will be coloued from absorbirig
particular rays,
and will exert a preferable or stronger action on Certain
these’ rays, to'which it has a preferable aflinity ; and, if its
action
30 DEC@MPCSITION OF LIGHT.
action on the two simple kinds do not give a marked pre.
-ponderance to one of them, it will be a mixed combination,
Absorb others that will first disappear. The mass of the body being
3n SUCCESSION, as . : 4 .
till byincreasing 8radually increased, the destruction of the rays will go
their thickness ‘hy new mixtures, still progressively ; the kind least acted
they transmit ¢ ! ° ; é
none; upon will remain the. last, and it will necessarily be one
of these three, red, green, or violet; after which no more.
light will be transmitted. Such are the phenomena of
absorption, and its different gradations. i
I shall give here one of the last results of my experi-
ments, which might have created some confusion, had it
been mixed with the preceding considerations, yet tends to
confirm their principles.
White pro- I had an inclination to try, whether the light from a
Bane ieee given part of the single spectrum, combined with that of
points ofthe another part chosen for the purpose, would produce
spectrum. white.
To carry this into execution, I placed before the image
of the spectram, received on the cloth a screen, by which
one portion was concealed, and another left open. ‘Fhis
screen, however, was perforated by a sinall hole, through
which passed a ray of coloured light belonging to that part
of the spectrum which was concealed. Lastly, this little
coloured ray was received on a metallic speculum, placed
between the screen and the cloth, and inclined so as to
throw it on a given paint of that part of the spectrum,
which arrived freely on the cloth. Thus the colour arising
from the mixture of two rays of light was observed.
I varied the trial of this apparatus on different points,
the corresponding tints of which were diametrically op-
Clearest white posite on the dial of colours. In several instances I did
teas ep °* not obtain a white free from all tint of colour, because, a
remity of the
red, and boun- Certain proportion in the quantity as well as quality of the
Tene elements is necessary: but having carried the little image
almost to the limit of the green and blue, it gave a decided
and bright white, when thrown on the extremity of the
‘ red. ie
This very remarkable fact adds fresh support to my
proposition respecting the compound state of the colour ip
certain parts of. the spectrum, sim plified tg the utmost,
For,
‘MATCHES FOR ARTILLERY. 3)
For, if the combination of the three colours. have mena
tioned be necessary to produce white, as every thing tends
to persuade us, we must admit the existence of violet in
the greenish blue with which the experiment was made.
‘N. B. It may be necessary to add, in explanation of
Fig. 2. Plate Il. that the colours of; the three circles are
distinguished by dotted lines; the red by round and long
points alternately; the green by one long-point and two
round; the violet by one long and three round.
VI.
Wooden Matches for Artillery to be used instead of Rope
Match, or Port-Fires: read at.the National Institute,
.. April 1806. Ly C. L. Caver*. r
For several centuries rope match only was used for firing Rope or com-
; 3 hop
Ari P 4
great guns, mortars, howitzers, and other pieces of ar- ™0" match.
tillery. ‘This match, as is well known, is a rope of supple
hemp, of a midling size, boiled for two hours in a bath of
‘saltpetre, ashes, quicklime, and horse-dung. This rope,
when. dried, barns slowly to the end, in the manner of
‘touchwood, and communicates its fire like red-hot coal.
For use it is twisted round a staff called a port-matcb, and
left to ‘project near five inches beyond its.end, this length
burning an hour.
This match has several inconveniences. It requires con- The incon. ,
stant attendance, since it must be unrolled from the staff Yeo
every hour, or oftener; a tolerably heavy rain puts it out;
it gives the artilleryman no light by night; and the oid
‘beyond the staff is not always steady, so that the gunner is
‘slow in firing his piece. In thése accounts its use is now
‘confined to garrisons, except for carrying fire in the field,
“where for other purposes port-fires are employed.
These port-fires are paper tubes, filled with a mixture Port-fres,
of sulphur, saltpetre, and a very little neat-powder. This
composition, the greater part of which is saltpetre, burns —
And melts with great activity, giving a vivid and bright
* Annales de Chimie, Sep. 1806, p. 314. -
flame,
32
Their advan-
tages.
Defects.
Particularly
dangerous at
sea.
Wood impreg-
nated with
nitrate of cop-
per, proposed
by ‘Borda and
Proust.
All wood not
equally good
for the purpose.
Nitrate of pot-
ash will not do.
Different woods
boiled with
nitrates of cop-
per and lead. ~
MATCHES \FQR ANTILLERY.
flame, which quickly sets fire to the priming. In this
respect they are far preferable to match, since they give
light to the gunner, their fire is more vivid, and they are
more easily guided; but these advantages are counter-
balanced by dangers and defects. The saltpetre in these
port-fires is never entirely burnt, but -part runs out of the
tube. When the materials are not well powdered, they
are subject to spit, or throw out pieces of burning salt-
petre to the distance of three or four fect, which may oc-
casion serious accidents, particularly on board ships. f
myself had my hair set on fire, and a hole burnt through
both my coats, by a spark of this kind. In ships they are
obliged to be kept in the middle of a tub of water on this
account. ah
’ These were the only means employed ta fire pieces of
artillery, when one of my correspondents at Madrid ac,
quainted me, that Messrs. Borda and Proust had proposed
to the Spanish government, to substitute instead of the
cannon match, wooden rods impregnated with nitrate of
copper. He added, that these rods burnt like touchwoad,
forming a pointed red coal; and that the trials with them
succeeded perfectly, though they had not been adopted.
I informed his excellency, the minister at war, of this new
method; and he requested me to make the necessary ex-
periments for ascertaining its utility, directing Mr. Les.
pagnol, a captain in the artillery, to assist me jn the
inquiry.
My first idea was, that ail kinds of wood could not be
equally fit for the purpose; and that the difference of their
porosity would occasion a difference in their combustibility.
Before I tricd the metallic nitrats, T took common salt.
petre, and boiled several kinds of wood in a strong solu;
tion of it, which they imbibed in different proportions.
This attempt did not succed; the only woed that burnt
quickly was the common cane, used for dusting clothes,
or rotang; but its coal had no substance, the least
blow breaking it off, and extinguishing it. I then got
a joiner to make me some square rods, half a yard long,
of oak, elm, ash, elder, birch, poplar, lime, and fir.
I took two parcels of these, and bailed one in a solution
of
MATCHES. FOR. ARTILLERY. ‘$3
of nitrate of copper, the other in a solution of nitrate
of lead. In each, the oak, elm, ash, and elder, were Oak, ash, elm,
not saturated, and burnt in the usual manner: the others and elder, do
afforded me very good matches. But before Iventer at Birch, poplar,
Jarge on their properties, I shall observe, that.1 conceive i andi, |
the nitrate of copper should be. rejected,.because it is too Nitrate of cop-
dear, it quickly corrodes the boilers, and its vapour is OR eae
noxious. Accordingly I confined myself to the nitrate of
lead ; and I found after several trials, that-it apnprest the
purpose completely.
The wood that did best was that af the lime, birch, or Lime, birch,
poplar. To compare their properties, I weighed some doa ee
both before and after boiling ; i ascertained how much their
weight was increased, and how long they continued burn.
ing; and J calculated how much of each a pound of nitrate
of lead would saturate. The following table gives the
proportions.
Name of the|Weight of a yard] Weight after. Gained in weight. Their proper-
wood betore the expe- : ties compared,
riment. iy
Grains. Grains. Grains.
Birch 888 1416 528 :
~» Poplar 516 936 420 Ah
Lime 888 1728 | 840
' Name of thejLength saturated by a!Time each con-
wood. pound of nitrate of|. tinued burn-
lead. ing.
Yards. Ft. Inches. Hours.
Birch 7S Ed 3
Poplar ES Oe 2
Lime 104. 2 9 3
From this comparative trial it follows, that the lime tree.
affords the best wood for matches for artillery; and with it
I made the experiments desired by the minister, in presence
of Mr. Lespagnol.
‘There are circumstances in which the service of the Light, some-
artillery requires light. _ Rods impregnated merely With er ee a
nitrate of lead, produce a coal sufficient to discharge a
cannon, but no light is afforded by them I conceived » Subsequent im-
that, if they were impregnated with oil of turpentine, they Presnation ibe
oil of turpen-
Vor. XVII. —JUNE, 1807; D might tine produced
this.
$A
Two other ad-
vantages in
this.
‘The author’s
theory.
Lead easily
reduced.
Its acetate con-
verts rope into
a match.
Light woods
absorb most
salt.
WATCHES FOR ARTILLERY.
might yicld flame, without detriment to the action of the
nitrate; and my hopes were realised, for rods thus pre-
pared furnished both light and fire at pleasure. In this
addition I found two other advantages: one, that of render-
ing the wooden match impervious to water; the other, that
of facilitating the reduction of the lead, part of which I
was apprehensive might be carried off in vapour, and in-
jure the health of those who respired it.
The theory of the process I adopted is simple ; and it is
easy to explain, why metallic nitrates succeed better than
nitrate of potash. However dry the wood may be, it al-
ways retains a little of its water of vegetation or of com-
position, which is an obstacle te its proper combustion.
By boiling the rods in a solution of nitrate of lead or of
copper, which on account of its specific gravity requires a
high temperature; this fluid dilates, softens, and penetrates
the fibres of the wood, and expels their water of vegeta-
tion, which is replaced by that of crystallization. The
nitrate then comes into immediate contact with the carbon
of the wood, whence the rapidity of its combustion.
The nitrate of potash does not answer so well, because, re-
taining much water of crystallization, its solution does not
acquire so high a temperature: and, supposing it able to
penetrate the wood as intimately, it carries into it too
much water, for its combustion to be progressive and.con-
tinual, A proof of this: reasoning may be found in the
composition of the two salts: nitrate of lead contains -75
of its base, that of potash but °49..
The rapid combustion of the wooden match is owing
also to the facility, with which the salts of lead are re-
duced, when in contact with burning charcoal. If a
hempen rope be boiled in a solution of acetate of lead, and
afterward dried, it may be used as a match. It burns
slowly like touchwood, and has a very bright coal. The
oxide of lead, as the metal is reduced, gives out its oxigen
to the carbon, and accelerates the combustion *.
On comparing the specific gravity of wood with its satu-
* We have a familiar instance of this in the popular experiment
of burning a red wafer in the flame of acandle. Ed.
ration
4
‘MATCHES FOR ARTILLERY. 35
ration by salts, we find, that the lighter the wood, the more
saline matter it absorbs into its pores, or the interstices of
_its fibres. Hence it appears to me we may infer, that it
contains less carbon than a heavier wood in a given bulk ;
and that its combustion will evolve less caloric, since the
caloric emitted is in the ratio of the quantity of oxigen
combined with the combustible. It seems to me, that we This absorp-
might class different kinds of wood, as to their combusti- reign
bility, by their absorption of salts; and thus find which bility.
would be most advantageous to burn for domestic purposes,
whether we would have a rapid combustion, or a stronger
and more continued heat. These rcsearches will form the
subject of a particular work, which I purpose on sve our
forest trees.
The wooden matches, compared with ainda have the Comparison be
tween the
follewing advantages. 9
The port-fire lasts but three or four minutes. and port-fires.
_A match a yard long will burn three hours.
The port-fire is liable to break in the boxes.
The match is strong, and easily carried about.
The port-fire throws out dangerous sparks:
The match confines its fire to itself.
The ‘port-fire costs from three pence to four pence half-
penny : ;
The match costs but three half-pence or two-pence.
The last consideration is of great importance, since, Great saving.
from calculations made in the war-office, what would cost |
the state in the one case a thousand pounds,-in the other
would not come to more than seventy-five*.
As it was necessary to ascertain, whether these new The wood
matches would resist the rain, I had several burnt during efitied
long and heavy rains, and they were not extinguished till by rain.
_ they were totally consumed; their combustion being a little
retarded only. |
As the fabrication of these matches requires some care Precautions ne-
and precaution, I shall conclude this paper with a minute 7 ad
_ description of the process, agreeably to the request of
* According to the estimates just before given, the saving would
be much greater than this on the lowest calculation. T.
Da his
Shape of the
match and
choice of the
wood.
Round inferior
te square.
The wood must
be thoroughly
ary,
Boilers.
Fumaces,
First boiler.
Second Boiler.
MATCHES FOR ARTILLERY.
his excellency the minister at war, for the instruction of the
artificers employed in our arsenals.
Method of preparing the combustible wooden Matches for
Artillery.— Shape of the Matches and Choice of Wood.
The matches should be parallelipedons, half a yard long,
and half an inch square. The best wood for them is that
of the lime tree, or birch; but for want of these, poplar
or fir may be used. Any white and soft wood might be
taken, if necessary; but those above-mentioned are to be
preferred.
The shape might be supposed. of no consequence: yet
experience proves, that round matches do not furnish so
good a fire as the square. The angles of the latter keep
the coal in the centre burning vividly, and the match al- _
ways terminates in a burning cone two inches long.
Drying the Wood.
Before the matches are saturated with nitrate of lead,
the wood must be perfectly dry. For this purpose the
wood should. have been cut and stored at least a twelve-
month ; and the matches, after they are shaped, be exposed
for half a day to the heat of a stove at 30° (by what ther-
mometer is not mentioned; probably 90°, or perhaps
100° Fh.) For want of a stove they may be put into a
baker’s oven, when the bread is drawn.
Furnaces and Boilers.
The fabrication of the matches requires two furnaces and
two boilers. The shape of the boilers should be that of 2
fish-kettle, narrow, and three quarters of a yard long.
Their size should be proportional to the quantity to be
made at a time. The furnaces should be constructed so
that the heat may act uniformly on every part of the bottom
of the boiler. The first boiler must. be of copper, well
tinned, and provided with a plate of the same metal, to
press down the matches, and keep them immersed in the
boiling solution. The second boiler maybe either of
copper or of cast iron, placed on a sand bath, and having
ne
|
:
;
7
MATCHES FOR ARTILLERY. 37
no direct communication with the fire. It should have a
lid fitted to it very closely; and handles to lift it wp when
necessary.
‘ Preparation of the Nitrate of Lead.
To make this salt, nitric acid, or aqua fortis, must be Mb tee
saturated with red oxide of lead, or with litharge: but as Jeaa,
it is necessary that the salt should be neutral, and have no
excess. either of acitl or of base, some precautions in this
operation are necessary. If the acid be too much concen-
trated,. the salt will unite in a mass, crystallize confusedly,
and contain a great deal of uncombined oxide. If too
little oxide be used, the salt will be acidulous, and soon
destroy the boilers. To obtain the mean term, 500 parts Augie of
of litharge should be put into a vessel of glass or earthen ' MBTeUSMS:
ware, and on this should be poured 416 parts of nitric
acid at 40°, (specific gravity we believe, 1.386) diluted
with 128 parts of water; heat the mixture till the oxide is
dissolved, filter, and evaporate to dryness. These pro-
portions ought to produce 640 parts of nitrate of lead.
Bath of Nitrate of Lead.
"The nitrate of Jead is ver y soluble in water, and the Jeast Liquor for the
possible quantity of liquid should be employed, that the ae
bath, fully loaded, may acguire a temperature far beyond
' that of boiling water, and thus insinuate itself easily into
the pores of the dilated wood. Accordingly, for every
pound of nitrate, only a wine quart of water should be
putinto the boiler, ov thereabout: but as different kinds
of wood do not saturate themselves equally with the salt,
their proportions must be studied. Experiment has shown “ls page a
that to absorb a pound of nitrate of lead, requires near ferent woods.
eleven yards of lime wood, 174 of birch, and near 22 of
poplar. The lime Winstone. when. guna, is the most
combustible.
_ To render the saturation of the wood complete, six Time of boil-
hours boiling are necessary, and hot water must be added, '"&
when the bath sinks so low as to let the salt fall to the
bottom.
Second drying. of the Matches.
Wi hen the matches are taken cut of the boiler, they must Second drying.
2 be .
—
38°
Boiling in oil
of turpentine.
{ntroduction.
Domestic in-
sects infest
dwellings in
DESTROYING INSECTS.
be carried to the stove, and made thoroughly dry, before:
they are put into the following bath.
Turpentine Bath.
Into the second boiler is to be put as much oil of tur-
pentine, as will cover the matches to the depth of about an
inch; and this is to be heated gently, till it begins to boil.
But the moment it grows white and rises, the boiler must
be covered, and quickly lifted off the sand bath, lest the
oil should take fire. This boiling should be repeated two
or three times, which will take about half an hour: the
bath then is to be left to cool; the matches are to be taken
out and wiped; and lastly they are to be dried in the stove,
when they will be ready for use.
This paper was approved by the Institute, at its mceting
on the 5th of May, on the report of Messrs. Carnot,
Deyeux, and Guyton de Morveau.
Vil.
Letter from a Correspondent on the Means of destroying
the Insects which infest the Houses in large Towns.
To Mr. NICHOLSON,
SIR,
As you do not think it beneath the dignity of your Journal
to descend to the disgusting, although often necesary
business of considering the best method of destroying bugs
and fleas, the following observations, suggested by your
correspondent A in the last number of your Journal, are at.
your service, if you think they are worth insertion. I
shall be very glad if they contribute to relieve your corre-
spendent or any other of your readers from one of the
** miseries of human life.”
I am, Sir,
Yours,
St. Mary-le-bone, May 6th, 1807.
Bugs are often intolerable pests in houses in large towns ;
more especially in inns, hotels, lodging-houses, &c. which
2 are.
DESTROYING INSECTS.” 89°
are exposed to continual importation of them upon clothes, instances
packages, &c. When once they get into a house, although where care and.
cleanliness are
the numbers may be kept under by cleanliness, frequently not sufficient
taking down the bedsteads, and’ washing them with various ™™¢diss.
kinds of poisonous washes; it is generally found that they
cannot be eradicated. Their eggs or knits, or at least
some of them resist the action of the poison, and after a
time fresh swarms are produced, who Jive and multiply,
especially in hot weather, in the apparently poisoned wood.
“Soon too they get into the wainscoat, skirting boards, or
lath and plaster walls of the room, from whence they send
forth fresh colonies as the former are destroyed.
Six years ago last September I took my present dwelling Account of a
house. The walls were repaired and white-washed. The aos mice
bedsteads, one excepted, were all new, and that one was
perfectly clean. Precautions were taken to prevent bugs
being introduced in any old boxes, &c. of the servant.
Karly in the spring all the bedsteads were, to my vexation
and surprize, overrun with bugs—one in particular must
have afforded habitation to several thousands.
They were all taken down and washed in soap and water, ve gear coe
the ends were dipped in boiling water and then in a hot de- medies.
coction of the cucumis colocynthin of Linncen, or bitter
apple as it is commonly called. In about six weeks it was
necessary to take them down again, They were now
washed in essential oil of turpentine, which kills this insect
almost instantly; but appears to have no effect on its nit,
and wholly evaporates ina few days. Therefore the joints
were well brushed with a strong solution of oxymuriate of
quicksilver, with which I hoped to render the wood
poisonous and uninhabitable to them, But I soon found
my hopes were vain.
About this time I Jearned from a neighbour, that during
the time of a gentleman who~had lived in the house above
twenty years, it had become overrun with this insect to a
degree that appeared incredible? and that, until his death,
he would not suffer his bedstead to be touched. The insects
were sometimes seen crawling even upon the walls of his
drawing room. After his decease millions were found
upon his bed and chamber furniture.
I need
40
Remedies
against the in-
sects which
infest our
houses.
DESTROYING INSECTS.-
I need hardly say that this intelligence and my expence
made me wish myself out of the house. But as I could not.
conveniently put my wish in execution, it was necessary to
try to get rid of my co-tenants.
The bedsteads were taken down every three or four
weeks during the summer and washed with decoction of
hellibore, solution of arsenic, and various other poisonous
washes. Generally some living bugs were found in them.
Early the next spring they were again taken down, and
we had the mortification to find fresh colonies had taken
possession, and were beginning to breed in the joints. .
The skirting boards of the bed rooms were now removed,
and in such rooms as were papered, all the loose paper was
removed, and the rooms were well fumigated with oxymu- -
riatic gas; after which the walls that were papered, were
covered with paint; for fresh papering walls infested with
this insect favors their increase.
The joints of the bedsteads were painted over with three
coats of oxyde of lead mixed with linseed oil and a little
rosin, so as to form a thick coat over the wood.
From this time, excepting a few stragglers who had got
into the joint and died there; the bedstead continued quite
free from the insect for two years, when a few were found
in some parts where the paint had been abraded. The
joints have since been painted over with a coat of thin paint
once in two years. <A precaution which I have used be-
. cause the walls are not free from them. During very warm
weather one or two are sometimes found upon the furniture ;
but such as get into the joints die.
Another bedstead, the joints of which happened to be
painted with Spanish brown; Hues were found in the
following year. |
Iwish this method may be found ae successful.
The joints should be made casy and free from splinters, alse
all cracks and useless holes should be immediately filled up.
If the insect has got into the walls the beds should atong
six or seyen inches from them.
On the subject ef fleas J have no experience. Where
from particylar local situations cleanliness alone is insufficient
to keep them away, the blankets ma ay be dipped, and the
. floor,
FABRICATION OF SULPHURIC’ ACID. | 4)
fic or washed in a decoction of the cucumis colocynthin, which
Iam told is poisonous to them. Your correspondent, if he
pleases, may rub his body with it—it is perfectly safe; or
he may put into his bed a bunch of fresh rue or savin, or
perhaps of any other strong smelling herb.
VI.
Theory of the Fabrication of Sulphuric Acid; read in the
Class of Physical and Mathematical Sciences of the French
National Institute, January the 20th, 1806, by Messrs.
Desormes and CLement.*
Durrrrent opinions are entertained respecting the Nitrate sup-
utility of nitrate of potash in the usual mode of fabricating apd ect OR
sulphuric acid. Some believe, that the high temperature perature,
produced by its deflagration determines the formation of
sulphuric acid; others imagine, that the nitrate affords. the afford oxigen,
quantity of oxigen necessary to complete the combustion, ‘i
which the atmospheric air has commenced: others again
suppose, that water may be decomposed in the process, &c.
We. shall here attempt only the refutation of the first and
second of these hypotheses, which apy pear at first sight the
most probable. )
_ The first cannot be maintained, because, at the same time Temperature
as nitrate of potash is addcd to the sulphur, clay and water elke a
are frequently mixed with it, each of which has the effect and water are
of diminishing ‘the temperature; one by ren dering the-com~,., P*<sen'-
bustion more slow ; the other by constantly absorbing a
large quantity of the caloric evolved, to acquire the state
of vapour. Besides, it is known, that sulphur burnt by
itself, at.a temperature of 1000° of the centigrade thegmo-
meter for instance (1832° F'.) affords no trace of sulphu-
Fic acid. . .
_The other hypothesis, -which docs not appear. so remote Oxigen of the
from the truth, is notwithstanding equally erroneous. pairs faa litle
admits, that the oxigen exiricated from the nitrate. of pot-sulphurous acid
ash js sufficient for the conversion of all the sulphureaus i’? ss!Phunc.
- @ An. de Chim. Vol. LIX. p. 329, Sept. 1806.
$i ik acid
42
Shewn by the
proportions of
their principles.
YABRICATION OF SULPHURIC ACID.
acid gas produced into sulphuric acid; but the contrary to
this is easily proved. The quantities of the elements that
concur in this operation, or result from it, are not known
with precision ; yet those we shall assume may be considered
‘as sufficiently near the truth to refute the second hypothesis.
Nitrate of potash contains about 0.30 of nitric acid;
which acid, according to Davy, contains 0.70 of oxigen.
In this nitrate therefore there are 0.70 — 0.30 =0.21 of
oxigen. Insulphurous acid there are about 0.59 of sul-
phur, and 0.41 of oxigen; and in sulphuric ‘acid 0,52 of
sulphur, and 0.48 of oxigen. Now if we employ a very -
large receiver, or long continuance in a small one into which
the air can enter, all the sulphur burnt with 4 of its weight
of nitrate of potash will be converted into sulphuric acid.
Thus, if we operate with 90 parts of sulphur and 10 of
nitrate of potash, we shall have = 152 of sulphu-
rous acid, which will produces =173 of sulphuric
acid, and consequently require 173—152=21 of oxigen.
But the 10 parts of nitrate of potash, employed in this
operation, could not give more than 2.1 of oxigen, or a
tenth of the quantity necessary to saturate the acid. Some
manufacturers carry the proportion of nitrate of potash to
the sulphur as far as 0.2; but in this case, which is the most
favourable to the hypothesis we controvert, the nitrate is
but 22 of what would suffice according to the proportions
admitted. The nitre therefore does not serve to produce
sulphuric acid, as has been supposed. If its oxigen be not
sufficient to convert the sulphurous acid into sulphuric, still
fess can it suffice to saturate the sulphur with oxigen, with-
out the assistance of the atmospheric air; and it is remark.
able, that the acid contained in the sulphate of potash, the
residuum of the combustion, contains more oxigen than the
nitrate could furnish.
If any doubt of the solidity of this reasoning remain,
on account of the uncertainty of the proportions of the
substances operating, they will soon be dissipated, when
the perspicuousness of the new theory is contrasted with
these vague opinions.
When
FABRICATION OF SULPHURIC ACID. AS
When we attentively observe the burning of the ordinary In the ordinary
mixture of sulphur, nitrate of potash, and wet clay, we Bee aoe.
perceive, that the nitric acid is not completely decomposed,
and that a great deal of nitrous acid gas passes into the leaden
chamber with the sulphurous acid. Its colour renders it
very visible, and it is a fact that cannot be questioned.
This observation affords a key to the true theory ; and in This the key te
following up its consequences we find the production of sul- scabies si
phuric acid clearly explained.
Weare certain, that the combustion extricates a mixture Recital of the-
of nitrous acid gas, and sulphurous acid, with water in va- ects.
pour, and nitrogen gas from the atmospheric air. We may
suppose too, that a portion of oxigen has escaped the ac-
tion of the sulphur. This supposition, which has nothing
in it that is not extremely probable, is the only thing on
which any doubt can be entertained. Now, from an ex- Nitric oxide
periment made purposely to ascertain this, the sulphurous eke yee
acid gas and nitrous acid gas cannot exist in contact, with- into sulphuric,.
out the latter being decomposed, and converting the former
into sulphuric acid; this then will take place, when such a
mixture of the two gases takes place in the leaden chamber.
Being then at a distance from the place of the combustion,
this mixture finds a lower temperature, which occasions the
condensation of part of the vapour; the rain thus formed
carries with it the sulphuric acid produced, and affords a
vacuum to the different substances that remain; these pre-
cipitate themselves into it in eddies, and present to each
other a thousand points of contact that favour the action of
their affinities,
After the first production of sulphuric acid, there remain The nitrous ox»
nitrous oxide gas, sulphurous acid, atmospheric air deprived “a iasoeaan
of part of its oxigen. The nitrous oxide necessarily con-from the air,
verts itself into nitrous acid, which will be again decom- es peat ad
posed to the profit of a second portion of sulphurous acid ; yields its oxi-
and this will go on till all the nitrous acid or atmospheric ene eg
oxigen, or both, are exhausted.
The first productions of sulphuric acid must be the most The sulphuric
; as acid produced
copious and rapid, because the condensation of the aqueous most copiously
vapour produces a great commotion in the mixture. of thet first,
different gases; and because too the abundance of the ox-
igen
Ad PABRICATION OF SUIPHURIC€ ACID.
igen and sulphurous acid render the contact more probable,
while, as they become less in quantity, the nitrogen, which
continues the same, renders their approximation more’ dif.
ficult.
Residuum, vi- After the whole of the sulphurous acid is converted into
trogen, nitrate sulphuric, the substances that remain are a great deal of ni.
St nur trogen, nitrous oxide, or nitrous acid gas, if there were at
oxigen. first more oxigen than the sulphurous acid required ; and per-
haps an excess of oxigen more than sufficient to saturate the
sulphurous and nitrous acids.
Quantity of ox- | What is of importance to be observed is the bade of the
ile of nitrogen nitric acid, the quantity of which cannot have varied, and
ae which ought to be as much after the production of all the —
sulphuric acid as at its extrication from the nitrate of potash.
This quantity of nitrous oxide, or nitrous acid, is probably
a little less than the nitrate could have produced, because in
the combustion the temperature may have been raised too
high, and then the complete decomposition of a small por-
tion of nitric acid takes place. We say a small portion,
because experience has shewn the advantage of keeping the
temperature very low by a suitable quantity of moisture. |
The nitric acid Thus the nitric acid is only the instrument of the com-
fey inter- plete oxigenation of the sulphur ; it is its base, the nitrous
acid, that takes oxigen from the atmospheric air, to present
it to the sulphuric acid in a state suitable to it.
Water indirect- We see that water is not directly necessary to the pro-
ly necessary. duction of sulphuric acid; its combination with what. is
formed merely effects the extrication of the nitrous acids
that must have combined with it. This gas, thus set free,
proceeds afresh to seek oxigen from the atmospheric air con- —
tained in the receiver, to unite it again with the sulphurous
acid. ‘The aqueous vapour has at the same time the double
advantage of producing a great commotion in the remaining
gases, and of. producing this evolution of nitrous acid gas ;
accordingly its utility has been perceived, and a quantity is
introduced, by the exhalations from the hearth, beside that
arising from the humidity of the mixture.
Thus setting out from the existence of nitrous acid and
sulphurous acid gases, we have followed the metamorphoses
these two bodies undergo, taking for our -ground-work
facts
FABRICATION OF SULPHURIC ACID. Ad
facts well ascertained; and have admitted only one. single
supposition, that of the existence of a portion of oxigen
still free after the passage of the air over the sulphur. If
this supposition should appear doubtfal, atleast it will cease
to be so, when we have shewn by experiment, that, ad-
mitting it, every thing takes place as we had conjectured,
By mixing in a transparent vessel the different. substances The whole pro-
q . , . cess may be
we have considered as essential to the operation, we can see <0 43 acre
whether the succession of combinations be such as we had vessel.
conceived. And it may be verified by putting into a glass
body sulphurous acid gas, atmospheric air, and nitrous ox
ide gas in small quantity, for instance 4, the weight of the
sulphureous acid; for we see the oxide grow red, and dif-
fuse itself throughout the whole space; then clouds of white
fumes roll across the vessel, and deposit themselves in shi-
ning stellated crystals against its sides. ‘These dense whirls
of sulphuric are succeeded by an appearance of clearness ;
and, if at this instant a little water be admitted, the crystals
of acid dissolve with great heat; the nitrous oxide gas, again
becoming free, changes afresh to a red vapour; and the
same phenomena re-commence, till all the atmospheric oxi-
gen is consumed, or all the sulphurous acid burnt.
The remaining gases are precisely those we mentioned in
our conjectures; for the colour of the nitrous acid appears
with almost all its first intensity; and after the operation is
completed, there is no more sme!l of sulphurous acid, but
a great deal of nitrogen, and of oily sulphurous acid on the
sides of the glass.
If in this combustion of the sulphurous acid there were Too much
too much contact between the gases and the water added, ¥@'ct would “se
either by great agitation of a little, or by the presence of a ray pein
large quantity, the operation would be very slow and in-
complete, because liquid nitric acid would be formed, which -
retaining its state, would have very little action on the gas
to be organized. *
* Tt-sometimes happens, that the decomposition of the nitrous The experi-
acid gas is carried so far as to the state of an oxidule of nitrogen ; Ment does ae
this too appears to arise from too great action of the water on this EN otis |
gas. Messrs. Berthollet and Guyton have ascribed to this the mis-
earriage of the experiment, when the contact of water is too great.
oe This
46 FABRICATION OF SULPHURIC ACID.
This experiment, the only one of the kind, leaves no
doubt respecting the theory of the fabrication of sulphuric
acid, which we have here offered, and which is only a sim-
The discovery ple exhibition of the facts. If the chain of ideas to be
pe Sig adopted, in order to arrive at the process actually pursued,
chance. and the few analogies this operation has to all that we know,
be considered, it will appear very fortunate, that chance
alone, in some sort led to the discovery; and that we were
then put in possession, without knowing it, of the only
process perhaps capable of furnishing sulphuric acid by the
combustion of sulphur in the air.
Advantages to ‘This theory, affording us the means of improving our
be expected knowledge of the proportion of the elements of sulphurous
from this : - A :
theory. and sulphuric acid, gives us some hope of discovering the
same mode of action in other chemical operations, perhaps
ill understood ; it likewise permits us to add some improve-
ments to the present mode from just principles; as the ex-
tent and form of the leaden chambers, and the management
of the fire, must be necessarily influenced by this hypothesis ;
but its first benefit will be a saving of almost the whole of
the nitrate of potash.
P.S. In the meeting of the Ist. of September, 1806,
the Physical and Mathematical Class of the National Insti-
tute ordered this paper to be printed in the collection of those
of learned contributors.
SS agnnStsunasnseneneerseneese ee
IX.
Facts toward a History of Cobalt and of Nickel, by Mr.
Proust; abridged by Mr. Curvreutt.*
Action of acids Subprur IC, muriatic, and nitric acids, oxide cobalt ia
en cobalt. the same manner. With the first and second hidrogen is
evolyed.
Sulphates.
Two sulphates. Of these there are two, one simple, the other a triple salt,
with the addition of potash or ammonia.
#@ Annales de Chimie, Vol. LX. p. 260, December, 1806.
1. The
HISTORY OF COBALT AND NI€KEL. AT
1. The simple sulphate has a taste slightly pungent, anda mele sul-
little bitter, with something metallic. Its crystals, which phate.
are of no great bulk, are sections of irregular octaedra
heaped together, of a gooseberry red colour, and unalter-
able in the air. By distillation they lose 42 per cent. of
water, and are rendered rose-coloured and opake. In this
state they can endure a red heat without being decomposed,
except in the points that touch the retort.
2. When sulphate of potash is mixed with the preceding Triplesulphate-
sulphate, we ebtain more bulky crystals, which are rhom-
boidal cubes. This triple salt is less soluble than the sim-
ple sulphate, and loses only 26 per cent. of water by dis-
tillation.
Carbonate.
Carbonate of potash produces 40 or 42 hundredth parts Carbonate.
of carbonate of cobalt with the simple sulphate. An ex.
cess of alkali dissolves a great part of the precipitate. Boil-
ing, or cold water, decomposes this solution.
Oxide at a Minimum.
A hundred parts of the carbonate, after the separation Greenish grey
of the water and carbonic acid, leave 60 or 62 of greenish egy
grey oxide. To have it very pure, the retort must be as
full as possible, and heated gradually. Without these pre-
cautions it will be mixed with oxide at a maximum, which
yields oxigen gas with muriatic acid, while that which is
pure does not yield an atom.
The grey oxide dissolves with heat in nitric acid, without Heated in the
yielding nitrous gas. Heated in contact with air it imme- oo
diately becomes black; an oxide of which part is carried and insoluble.
to the maximum is elisity detected by the application of a
_ weak acid, which dissolves only the oxide at a minimum.
Ammonia produces the same separation, as Thenard. ob-
‘served.
Oxide by Precipitation.
1. A few drops of nitrate of cobalt dropped into bodling Nitrate preci-
water alkalized with potash give a blue precipitate, which Pi'ted by pot
ash and con-
_ ultimately becomes of a rose colour, if the boiling be con- verted intoa
fioued. In this case a hidrat is formed. at by boil-
2. AF
4S : HISTORY OF COBALT AND NICKEL.
Without heat 2. If cold alkalized water be employed, the blue preci:
the precipitate nitate 4s formed likewise; but, instead of constituting a
aS green. sj 2 z vy
hidrat, it pdsses-to green, without the contact of air . being
capable of obscuring its tint, which it retains after it is dried.
Changed to2 3. If this green precipitate; when fresh made, be boiled
grey by boiling. in water alkalized with potash, it becomes of a reddish grey,
and changes no further. .
” Action of acids Very weak acids, as vinegar for instance, tony dissolve
on the preci- the first precipitate. Applied to the other two, they sepa-
a tc rate from it black oxide. Lastly, the blue oxide pert no
gas with muriatic acid, but the green does.
Green oxidea Hence we must conclude, that the blue oxide oxigenizes
compound of jfself at the expence of the air contained in cold liquors,
the blueand eee : A
Back. and that the green oxide is a mixture of blue oxide and black
oxide. Mr. Proust however thinks, that something more
than simple mixture takes place; for blue and black would
not produce that grass green colour, which distinguishes it
from every other oxide. A true combination alone could
form a colour different from that of the mixture of its com-
ponent parts, and prevetit the action of the air from raising
to a. maximum the portion of blue oxide, which makes 2
part. of the grecn pretipitate. To oxide this precipitate
completely, it must be dried with the assistance of ney as
Thenard shewed. 3
The reddish grey precipitate of the third experiment is 2
mixture of hidrat and black oxide.
Maximum ox. °- Lhe oxide at a minimum only is capable of combining
a only solu- with acids. ‘The green oxide'is never obtained from any so-
; lution, and cannot become the base of any saline combina~
tion.
Ammonia and Oude of Cobalt.
Dissolves with If the grey oxide be enclosed with ammonia in a well
etbeulty in’ stopped phial, it ts to ita slight 1 hich
ainménix, stopped phial, it imparts to ita slight rose colour, whic
ee docs not become deeper, however long ‘itmay! be kept. This
oxide is consequently very difficult! ly soluble in ammonia.—
readily inits But if the phial beleft open, the ammonia becomes coloured
re very quickly, because it attracts carbonic acid from the air.
This solution may~be effected in a'very little time, by plac.
ing the phial in a large jar containing a carbonate.
If
HISTORY OF COBALT AND NICKEL. 49
If the ammonia be merely saturated with carbonic avid, This a solution
the liquid will be a solution of oxide of cobalt in carbonat ie
‘ef ammonia: but if we continue to pass corbonic acid into
this solution, we obtain a solution of carbonat of cobalt in or of carbonat.
‘carbonat of ammonia. This solution, kept in a full bottle
corked, de}. osits crystals of metallic carbonate; it likewise
lets fall a part on the addition of water; but an excess of -
ammonia redissolves this precipitate.
This solution may be made very quickly, by throwing car- Made ae
bonat of cobalt into carbonat of ammonia.
If pure ammonia be poured on carbonat of cobalt with Ammonia with
excess of acid, what occurs is very different. The carbonat Bie ay of
of ‘cobalt separates into two parts; one gives out its acid to
the ammonia, and becomes a hidrat, which falls to the bot-
tom of the vessel; while the portion not decomposed dis-
; solves i in the carbonat of ammonia.
Thus we have two kinds of ammoniacal solutions of co-
balt ; ; and there isa third, which Taffaret observed, but
which has been hitherto little noticed. This is obtained by
putting well washed hidrat, or blue oxide, into a phial full and with hidvat,
of ammonia, and closely stopped. A solution will take place ™ blue omaite.
in the course of four and twenty hours. This is red, like
the preceding; but differs from them: in this, that, if it
be poured in a very slender stream into boiling water, blue
oxide will immediately be precipitated; if into cold water,
green oxide will be obtained. If ammonia dissolve hidrat of
cobalt, or blue oxide frésh made, more readily than the gray
oxide, it is because they are in a state of extreme division.
Distillation of ammoniacal solutions.
When carbonated solution of cobalt are distilled, carbonaté The carbonated
of ammonia passes over, and at length the liquor lets fall an ee is
oxide, which is at first of a dirty green, but which afterwards cobait more
becomes black.’ This is a mixture of the gray and black °*#e4-
Oxides.
‘How is this superokidation effected ? The author sie
the facts, but does not endeayour to ee them, when
oo are wanting.
fy en. XVIL<June, 1807. E Bidege “ornne ee
50 ISTORY OF COBALT AND NICKEL,
“rf? 1, - . antawt
aka >! 3 - Hidrat of Cobalt.
Hidvat of | Crystals of sulphat or nitrat of cobalt, thrown into a bottle
sala filled with a solution of potash, and immediately corked v up,
are decomposed. A blue precipitate is fornaed, which changes
to a violet,and zfterwards to a rose colour, becoming a
hidrat.
decomposedby Ifthe hidrat of cobalt be boiled with potash, this dissolves
ae: some oxide, and acquires a fine blue colour. This solution
i is decomposed by the addition of water. By exposure to the
air the oxide becomes black, and falls down.
AL Ca EA Hidrat fresh made dissolves without heat in carbonat of
in its carbonat. notashy and tinges it red. The oxide does not dissolve if
Characters of - The hidrat of cobalt is. of a rosy feuillemorte colour.
the hidrat. Acids dissolve it with heat, and without effervescence.
The hidrat is not decomposed by boiling either in pure or
in alkalized water. Heat expels from it 20 or 21 of water,
sabid aud reduces it to very pure gray oxide. a
ose It dees not keep well under water; when it is exposed te
the contact of air, it grows black. Dry hidrat keeps better,
but it attacts carbonic acid. .
Dissolves in _ When crystals of sulphat of cobalt are thrown into a phial
msi a Ae full of ammonia, which is immediately closed, they yield a
siilphat. blue precipitate, which does not become rose coloured, as in
potash. Mr, Proust affirms, that the hidrat is formed, but
that as fast as it is produced it dissolves in the ammonia; se
that it is the hidrat that colours the solution, and not the
‘simple oxide.
i € Estimation of the quantity of oxigen in the oxide at a minimum,
Gray.oxide yor eas fesmtc oi parts of gray oxide, reduced with the requisite
seheeae _ pregautions in a closed crucible, afforded 83.°5 of metallic
omigen. ; grains, One hundred parts of the metal therefore appear. te
absorb nineteen of oxiggmto become oxide at a minimum.
LY )
Oxide at a maximum.
Black oxide 20 , Tf a nitric solution of cobalt’ be distilled, black incrustations
por cent, , ’ will
HISTORY OF COBALT AND. NICKEL, §]
will be deposited on the sides of the retort, nitrous gas will
be evolved, and the residuum obtained will be black oxide.
The quantity will be in the proportion of 125 or 126 parts to
. 00 of the metalin thesolution. Hence we may infer, that the
maximum of the oxidation of cobalt is between 2g or 26 of
oxigen to a hundred parts of the metal,
This oxide is not soluble either in the nitric or sulphuric Insoluble in
acid, without losing that portion of oxigen, which converts pa ae
it to the state of a maximum.
With muriatic acid it gives out oxigen gas.
It is insoluble both in d4mmonia and in potash. and in alkalies,
The black oxide, heated for half an hour at the bottom of a Heat converts
retort, returns to the state of gray oxide by parting with oxi- *tosray oxides
gen ; and it is then capable of giving a blue tint to vitrifiable
substances. :
Messrs. Proust and Thalaker have met with the black Native.
oxide at Pavias, a day’s journey from Valentia. - It is found
likewise in those ores of cobalt which are termed irtreats, or
- black ores.
The corbonat and hidrat of cobalt aré changed into black From carbe-
oxide by oxigenized muriatic acid. aac
The nitrous and sulphurous acids dissolve the black oxide, Soluble in ni-
trous and sul-
forming with it nitrat and sulphat at a minimum. ghiueois ‘acids:
Muriat of Cobalt.
~The gray oxide fetta with heat in mutiatic atid of 15°, Blue, or an- :
The solution, whether hot or cold, is of a deep bltie : it cry- pote apa
stallizes easily, and the crystals are blue: this is the anhidrous
muriat. -As soon as it has absorbed moisture, it becomes red.
Muriatic acid of 15° yields much gas with the black oxide.
This solution is green as long as it retains any: gas; but as
soon as it has lost it, it becomes blue. The biue traces of
muriat of cobalt dried on paper areanhidrous muriatic. When Greén imuriat
they are green, it is because the salt still contains muriat of nome he
niekel, “which gives a yellow tinge, and thus forms green with
the blue.
Its distillation.
nl bed to redness in a luted retort, it is decomposed.oniy in Heated, what
eu E.3 the touches the
glass is decenr
52
MYSTORY OF COBALT AND NICKEL.
posed, the rest the parts that touch the glass. The products then are
sublimes,
Arsenit, how
prepared.
Its characters.
“@ rzeniat.
tts characters.
Native.
inuriatic acid gas mingled with oxigenized acid. The glass
becomes tinged with blue. The muriat that is not decomposed
sublimes, after having melted, in flowers of a gridelin colour.
These flowers have acquired a kind of condensation, which
renders them insoluble in water for twelve hours at least :
but at length they afford a solution of ordinary muriat. :
Arsenit and Arseniat,
The Arsenit of cobalt is prepared by pouring a very dilute
solution of cobalt into a solution of arsenit of potash. A rosy
precipitate is formed, which retains this colour after desicca-
tion.
Character of the Arsenit. ‘i
1. Heated in a tube closed at one end it is decomposed ; the
oxide of arsenic sublimes; and the glass is tinged blue. |
2. The nitric acid dissolves it, and nitrous gas is evoled.
3. Its solution in muriatic acid is decomposed by my
retted hidrogen, which precipitates orpiment. a
4. Caustic potash, assisted by heat, separates the blue
exide.
Arseniat.
This is obtained by employing arseniat of potash, instead
ef arsenit. The precipitate is rose-coloured like the arsenit..
Its Characters.
r. Heated in a tube it yields no sublimate, and becomes
violet-coloured, without tinging the glass.
2. Nitric acid dissolves it without giving out nitrous gas. —
. Its muriatic solution does not become turbid by the ad-
dition of sulphuretted hidrogen in less than two hours after
they are mixed.
4. Caustic.potash Sepatates blue oxide and combines with
the acid.
‘Lhe rosy eMirrnsaehati found or minerals containing cobalt
consist
BYSTORY OF, COBALT. AND NICKEL. 33,
consist of arseniat. Mr. Proust found arseniat only in the
interior parts of some fragments. .
Hidrosutphuretted oxide, Sulphuret of Cobalt.
The gray oxide, the hidrat, and the carbonat, take sulphu- Hidrosulphe-
retted hidrogen from water,and become hidrosutphuretted "et
oxide. This is not soluble in ammonia. By distillation it .
gives out water and sulphurous acid, and the residuum is a and dean
sulphuret. | ' mei
The oxides heated with sulphur are caneeeea into sul,
phurets.
One hundred parts of cobalt absorb. forty of sulphur ;
though Mr. Proust has some doubts respecting this pror
portion. wy
Facts toward a history of Nickel,
; Nitrat of Nicket.
A hundred parts of the metal dissolved in nitric acid, and Nitrat of
distilled till they are completely decomposed, leave 125 or ™ckel-
126 of greenish gray oxide ata minimum. Nitric acid can,
not convert this oxide to the maximum state.
To ascertain the purity of the oxide of nickel, it must be Test of its
dissolved in muriatic acid, and exposed to the action of heat. P&™#*Y-
If it contain a little oxide of cobalt, oxigenized muriatic
acid gas’ will be Set if it be pure, more will be given
out.
The gray oxide dissolves in all the acids. and affords. the
same solutions as the metal itself.
Nitrat at @ Minimun,
Pat nitrat of nickel be distilled with the same precautions as yrinimum
nitrat of copper, we obtain, as with the latter, a nitrat. with “aaa eal
excess of base, which is insoluble in water. Of this nitrat 142 17.6, acid 12.
parts are afforded by 100 of nickel ; so that, if we substract
‘the 25 parts of oxigen, which the metal has absorbed, we have
AM parts, of acid combined with the oxide,
AERTS Nitrate
54. HISTORY OF COBALT AND NICKEL.
Nitrat at a maximum.
Maximum, 100 parts of dry nitrat of nickel yielded by distillation 20 of
nickel 20, oxi- pd ta 8 : :
gen 5, acid 55, Water and 25 of oxide; consequently contained -55 of acid,
water 20, These proportions are not exact, as the last portion of water
were acidulous.
Muriat of Nickel.
Muriat. ‘This is a very deliquescent, apple-green, granulous erystal-
lization.
Its traces on paper, when dry, are yellow.
Contains 35. This muriat loses 55 of water. What remains is a véllong
wage anhidrous muriat, changing green again in the air, by absorbing
water.
Aphidrops If the anhidrous muriat be laeal on the fire ina afaes
muriat.
retort, and the heat strongly urged, it does not melt; the parts
that touch the glass are decomposed 5, muriatic and oxigenized .
muriatic acid are evolved; and the undecomposed salt sub-
limes in the form of flowers like mother-of-pearl, of a golden
yellow colour. These flowers absorb moisture, and become
green in the course of a couple of days. The muriatic acid
dissolves them with difficulty.
ih aha 100 parts.of muriat of nickel, decomposed by carbonat of
riatic acid 11-5, potash, produced 61 or 62 of carbonat, which infers 33 or 34
of oxide.
Sulphat of Nickel.
Two sulphats. This is either simple, or combined with potash. The first
crystallizes in hexaedral pressure, terminated by ancirregular
pyramid: the second, in rhomboids,
Simple sulphat. The simple sulphat loses 46 of water; and the anhidrous
re iduum becomes green again by absorbing moisture, kept at
a strong red heat for an hour in a luted retort it is reduced in
part to the state of sulphat with excess of base. The wos
takes up that which has lost none of its acid. ex
100 parts of this sulphat afforded 64 of a light green cars:
honat.
Triple sul- The triple salt with potash loses 24 of water. The resi-
phat. duuny
;
;
;
;
‘OMISTORY OF COBALT AND “NICKEL© BD .
duum comports itself like’that of the simple sulphat.. 100
parts of this salt afford but 27 or 28 per cent. of carbonat. =
Both, these sulphats of nickel are transparent, of a ‘fine
emerald green, and unalterable in the air. Mr. Proust is of
opinion that the sulphat of potash unites with that of nickel: in
a constant proportion.
Ext raction of Nickel in the large way.
Suppose we have an abundant solution of. the. ore; first Method of ob-:
calcined, and afterward vitriolized with the residuums of ether. a peas
The. business.,is, to separate the nickel, from iron, copper,
arsenic, bismuth, and cobalt. . The: iron is;at amaximum of ss ~~
oxidation, and in this state has little affinity with acids. It Iren precipi-"
may be precipitated then in the state of arseniat, by means. of “*€¢ by potash.
potash gradually. added. Ammonia, ‘or a prussiat, will after-
wwrad: indicate, whether it be entirely thrown down... | ~
» Anto the filtered solution let a stream of sulphurated hidrogen Copper, bis- «
muth, and
be passed the copper, bis muth, and all the arsenic, will. be...) ce sia,
precipitated in the state of sulphuret. i phuretted .
hidrogen.
When the sulphuretted hidrogen no longer occasions any guiphat of
precipitate, the liquor is to be evaporated for crystallization. backel from that
The triple sulphat of nickel and potash, being less soluble than bcs ithe do- ol
shat,of cobalt, crystallizes first. » By repeating the crystalliza-
tions the two salts are separated:; but the last portions of the
salt of nickel will be contaminated with some sulphat of cobalt, and ablution,
.from which they may be freed by washing in cold water. ~ wine
All these erystallizations require a basis of fine silver, if we insilver vessels.
would have the operations go on smoothly. '
‘A salt of nickel is known to be pure, when the moan fi ate® Test of its
“dissolved in ammonia, quits this solvent, without our finding Peer:
any cobalt at the end. ,
» When we precipitate a sulphat of nickel, we must not be ‘Sufficient pot-
_ too sparing of potash, otherwise we shall be.in danger of pre- used,
. cipitating sulphat with excess of base, which would affect the
ei rity of the precipitate,
s
Chrbiatias “A Nickel.
oP hundred parts, heated in a retort, five 54 or 55 of green- ae of
. ICK@le
ish
Hidrat.
In this state in
ajl its salts.
Oxide at a
maximum.
Black.
- Oxigen expe)-
led by ammo-
nia.
HYSTORY OF COBALT AND NICKEL.
‘ish gray oxide at a minimum. When heated in contact with
the air, the oxide is black.
The minimum oxide is converted into carbonat by Hei woerig
to the air.
Hidrat of Nickel.
All the salts of nickel, thrown into a boiling solution of
potash, are converted into a green hidrat. Boiling does not
alter its colour. Potash does not dissolve either the hidrat or
oxide of nickel.
The hidrat is reduced to gray oxide by heating.
In the saline combinations the oxide is in the state of hi-
drat. Alkalis precipitate it in this state,
Maximum oxide of Nickel.
The carbonat and hidrat are both oxided to a maximum by
the action of oxigenized muriatic acid. The gray oxide is
more difficult to oxide,
The dry oxide of nickel at a maximum is black. When
solid its fracture is vitreous,
This oxide kept in ammonia gives out bubbles, returns to
the state of gray oxide, and dissolves in the alkali.
With muriatie acid at 15° it yields a considerable’ quantity
of oxigenized acid. The solution is greenish yellow, and crys
Oxides re-
duced.
Sulphuret. °
Arsenit.
tals form in it by cooling,
The oxides of nickel are reduced like that of cobalt, The
metal is obtained pretty easily in a button, in which it differs ;
from cobalt, this affording only large grains,
This metal appears to have taken up a surcharge of sulphur
of 46 per ceit.; but Mr. Proust entertains some doubt of the
accuracy of this proportion.
Arsenit and Arseniat.
These are made like those of cobalt, and are of a fine apple-
green colour.
The arsenit, heated-in a tube, loses its colour en 4 its water;
gives out white oxide, and changes to an olive green. To abs
stractallthe arsenic the contact of charcoal is requisite.
Heated
HISTORY OF COBALT AND NICKEL, _ 5T
Heated under charcoal in a spoon of platina, the arsenic is
quickly dissipated, and oxide at a minimum remains.
The arseniat, heated in a tube, loses its colour with its Arseniat.
water; becomes transparent and of a hyacinth red ; but if the
heat be carried to redness it turns of a pale yellow, and remains
unalterable. nn ;
In the spoon the arseniat turns. white, and grows red hot
without melting, or emitting the least atsenical fume. ‘To
decompose itan obscure flame is required,
Recapitulation.
/
From the preceding facts, and others which he hasgiven in vost metals
different memoirs, Mr. Proust concludes, that cobalt, nickel, have but two
and most of the well known metals, have but two very decided ae
deerees of oxidation. He dees not mean to say, thata metal
can absorb oxigen in too proportions only : he only asserts, that at least that are
it is too soon to admit all-the oxides which have been mention- Yet known,
ed by chemists, and of which neither the quantity of oxigen,
nor the combinations they are capable of forming with acids,
can be considered as determined ; and that colour is not a
character sufficient to constitute a distinction. | lz
There are but too metals, that have hitherto afforded bhin¥ The anly ex-
more than two oxides. © These are tin and lead. However; the ins aha tin and
quantity ofoxigenin that oxide of tin, which constitutes the base
of mosaic gold, is not yet known; or that of the oxide of nitrat
of lead ‘made by boiling with plates‘of this’ metal. : at nebixe
> Ft seems, that the different oxides of the same metal can mu- Oxides of the.
tually dissolve cach other, and form true combinations, © 'Thus Same metal
the green oxide of cobalt is a com bination of the blue and sig aie acid
oxides, ©
Is not minimum a combination of the brown oxide of lead Minimum per-
and oxide at 9 per cent. ina similar manner? Hane Satie
Finally, all the magnetic ores of iron, and magnetic sands are Magnetic i iron
mixtures or combinations of this order. If this were not the es pice’
case what would prevent the minimum oxide from being raised to
a maximum of oxidation? “The oxide of a gun-barrel that has
been used for decomposing water is likewise ix a similar jes,
it is composed of two oxides.
XI.
t.
58
Histary of the
gallic acid.
Scheele first
extracted it.
Deyeux sub-
limed it.
Some facts by
*Bartholdi
unmnotic2d.
”
.
HISTORY OF THE GALLIC ACID,
At,
Facts toward a History of the Gallic Acid. By Bovit1o0x
LAGRANGE.”
I HAVE had the honour of submitting to the class the result
of my experiments on tannin; I now ae before it some. facts
respecting the gallic acid, which I had announeed as forming
the second part of my memoir.
Of all the vegetable acids, the gallic may be considered as
most interesting, and accordingly it hasbeen a. subject of inquiry
to many chemists. Macquer, Monnet, Lewis, Cartheuser, and
Gioanetti, pointed out the manner, in which solutions of iron
are acted upon by substances called astringent. The acade-
micians of Dijon were the first, who observed the presence of an
acid in those subtances; and in 1772 they shewed, that the
distilled products of nutgalls blackened the solution of sulphat
of iron, and that an infusion of them reddened the tincture of
bitmus. These particulars afforded only a general proof of the
acid nature of the principle contained in galls; offering: no
means of extiacting this acid, and obtaining it separate, for
which we are indebted to Scheele. His process was published
in 1780. A few years after, in 1795, Mr. Deyeux discovered
that this acid might be obtained by sublimation. | Messrs,
Berthollet and Proust afterward added much by their researches
to our knowledge of the properties of this acid; so that it’
might be considered among the best known of all that the vege~
table kingdom produces.
Several fotciga chemists too, within these few years, have
given processes for extracting and purifying this acid: but none
of them, except Richter’s, can come in competition with
Scheele’s. Among the many experiments, that. have-been
made on this subject, there is one, which I have neither seen
refuted nor quoted in the papers published on the gallic acid.»
In a letter from Mr, G. C. Bartholdi to Mr. Bertholict,
dated 1792, there are some facts, that might have claimed tho.
gitention of chemists, ._ enw
* Annales de Chimie, Vol. LX, p. 196, Nov. 1806,
HISTORY OF THE GALLIC activ. 59
b
Mr. Bartholdi first points out a process: for obtaining pure Oxiding sub-
gallic acid: he afterward treats this acid with metallic oxides; per aaa
and he says he has demonstrated, that all substances, which by slightly
Yield oxigen to the gallic acid, give it a brown colour; and Ch@ties it.
that, in this process, it is the acid itself, which, being charred,
forms by a slight combustion the colouring matter,
To show this, he boiled red oxide of mercury for half an Boiled with
hour in a solution of gallic acid, which assumed a blackish hue. a
Jn the residuum he found fluid mercury, mixed with a coally was produced,
powder : he afterward saturated the liqour with carbonate of cetera ~
potash and soda, and the salts thus produced afforded no blue iron,
precipitate with sulphat ofiron.
He obtained the same result with oxide of manganese, Oxide of man-
Other experiments convinced Mr. Bartholdi, that substances, 8"ese the
by which oxigen js abstracted from gallic acid, renders its Dies ;
genizing
colour lighter. I rendered, he says, a solution of gallic acid S¥bstanees
as limpid as uistilled water, by boiling it for some time with per eae gale
very pure and well powdered charcoal, ef which I took double
the weight of the acid: it retained its limpidity as long as I
excluded the influence of the atmospheric air from it, and it
precipitated iron black.
Mr. Bartholdi presumes, that we may thus effect the de- Its astrin-
struction ofits astringent property. ee ae
On this I shall not for the present make any observations , :
as it is necessary to be acquainted with the following experi-
ments, to judge them explicitly,
Extraction of the Gallic Acid.
There are seyeral processes for extracting the acid front Modes of ex- _
alls, tracting the
es gallic acid,
Scheele’s process.
' On one part of gall. nuts bruised and passed through a coarse gcheele's.
gieve, pour six parts of cold water. Let them macerate in a
glass jar four days, shaking them frequently: then filter, and
expose the liquor to the open air in the same jar, covered only
with blotting-paper. In a month’s time the liquor will be
govered with a thick pellicle of mould, without any precipitate
bejng
60
to
Barthcld?’s.
.
Deycux,
Ry¥cher's
HISTORY OF THE GALLIC ‘ACIB, .
being formed; and it will have lost its astringent taste, but be
acid. Qn leaving the liquor at rest five weeks longer, a preci+
pitate will be formed two fingers thick, and a mumous pellicle
ahove it. The liquor is now ¢o he filtered again, and left anew
exposed to the air. Atthe expiration of some months, the
greater part of the liquor will be evaporated : all the precipis
tates are to be added together, and cold water is to be poured
on them; when the liquor has stood to settle, what is clear is
to be decanted off: as much hot water as is necessary for the
solution is poured on; and by evaporating with a gentle heat
yellow crystals will be obtained. 3
Mr. Bartholdi’s process.
A tincture of galls in alcohol is to be evaporated ; the resi-
duum is to be dissolved in distilled water; and sulphuric acid
is to be added to the solution, till the mixture is decidely acid
to the taste. In the course of a few hours the éxtractive mat-
ter will fall down, and the supernatant fluid, freed from sulphu-
ric acid _by barytes, will yield, according to the author, pure
gallic acid. 6
This process by no means gives this result. It is in gencral
very difficult to seize the moment when all the sulphuric acid
is removed by the barytes, since it combines with the gallic
acid likewise: and after the liquor is ev aporated nothing
remains but an acerb matter, containing a great deal of tannin,
and insusecptible of crystallization.
Process of Mr. Deyeux.
This chemist discovered, that, by heating bruised nutgalis
slowly, and cautiously, in a glass retort, a pretty considerable
quantity of lamellated, shining, and silvery crystals was sub-
limed.
.
Mr, Richter's, process.
Nutgalls reduced to a fine powder are to be macerated in
cold water, shaking the mixture frequently. After some ime
the liquor is to be st®ained off through a cloth: the residuums
1s tobe macerated in afresh portion of water, and after it has
been
HISTORY GF THE “GALLIC ACID: 6}
ech subjected to the press, the two liquors are to be mixed,
and evaporated by a very gentle hcat. Thus we obtain a dark
brown substance, very brittle, which being reduced to a fine
powder, and digested in very pure alcohol, tinges.it of a very
faint straw colour. A second infusion extracts scarcely any ro
colour, and leaves a brown residuum, which is tannin: nearly:
pure. The two alcoholic tinctures are then to be mixed, and
distilled in a small retort, till seven-eighths have passed over.
The remaining liquor on cooling becomes nearly solid: water,
is poured on this, and by gently heating a limpid solution is ( eittiae
ebtained with very little colour. 5
Tf this solution be evaporated, very small and very adie
prismatic crystals are-obtained. The mother-water affords yet,
more, but they are commonly a little coloured: these however,
may be rendered very white by washing them with water. By, .
this process a pound of galls affords half an ounce of crystals.
They are extremely light.
The processes of Scheele, Deyeux, and Richter, have afford. Gallic acid
ed advantageous results ; but they differ with respect. to the nee
purity of the acid. ‘The acid produced by the first, as Ber- contains tan-
thollet. observes, retains a great deal of tannin; that by the”... ;
second is perfectly white; that by the third likewise contains >
tannin.
By Richter’s proccss the acid, after Seine purified, is "of a In, Richtei’s!,45
pale straw colour. I attempted in vain to bring it to the state pen
of purity mentioned by the author. I found, that if the evapo- tions in alcohol
: Pa ‘decomposes the
ration, desication, and subsequent solution in alcohol were con- aoig.
tinued, a certain quantity of acid was decomposed every time ;-
@ that the alcoholic tincture, instead of being more transpa-
rent, became brown, There is a certain point therefore, where
we must stop, if we would preserve the whale of the acid and
its propertics.
Mv. Berthollet tried different modes of purifying Schecle’s Berthottet pt-
acid. That which succeeded best with him was treating the ben ee
acid with oxide of tin recently precipitated from its solution in
an acid.
This experiment I repeated. The following -is the method Thig repeated -
I pursued, and the phenomena I observed. by ple: suthots;
After having separated the oxide of mutiat of tin by an
a: alkaline
62 HISTORY OF THE GABLIC actD.
alkaline base, I washed it well with boiling, water, and then
boiled it for some time in a fresh quantity of water. I then
treated it with gallic acid, and evaporated to the consi-tence of
thick honey. I then added distilled water: and.the liquor,
without pro- after being filtered, was colourless, limpid, without taste, and
= without smell. On evaporating to dryness nothing remained.
This difference from the result obtained by Mr. Berthollet
Jed me to suspect, that I had fallen into some error. T there-
foxe repeated the experiment with all the attention possible.
Further trial. I dissolved 61 grammes of gallic acid, confusedly crystallized
and very brown-in 500 grammes of boiling water. Part of this
solution ] set by as a standard of comparison; the rest I boiled
with 61 grammes of oxide of fin well washed, and still wet.
When about half the liquor was wasted, I made it up to its
original weight with fresh water, compared it with the standard,
and found it had lost a great deal efits colour. The difference
of acidity was scarcely perceptible. It still precipitated glue :
but the precipitate was yellow and floculent, while that of the
solution not purified was brown, heavy, more copious, and even
united ina mass. It appears, that the acid was not yet decom-
Did not sue- posed: but I could not obtain crystals equally white and pure
weed. with those afforded by sublimation, as Mr. Berthollet did.
More oxide - Desirous of knowing whether a fresh quantity of oxide of tin
pee aa would deprive the acid of tannin entirely, I added to the liquor
30 grammes of oxide of tin, and evaporated till about 100
srammes of liquor only remained, It passed through the filter
clear and colourless, and precipitated neither sulphat of iron .
nor glue. {I could not ob‘ain any gallic acid by evaporation.
This experiment proves, that itis very difficult to free gallie
acid completely from tannin ; and that by repeating the action
Proust found of oxide of tin the acid is decomposed. Thus no doubt, Mr.
the same, Proust procecded ; for this chemist observed, in his memoir
printed in the Annales de Chime, vol. 42., that the oxide of tin
he employed to purify the gallic acid afforded him as a product
only a colourless insipid liquor, without taste, and not having
the slightest effect on solutions of iron or tincture of litmus.
Bartholdi’sex- As to the means proposed by Mr. Bartholdi, I do not
ada, imagine they can be employed. Yet, as the author neglected
to examine the products of-bis operations, I thought it neeessary
te
‘ ? :
HISTORYOR THE GALLIC ACID: 63
‘to repeat his experjments, and determine the nature ef the results
that might arise from them, With thisview I poureda solution With red oxide
of gallic: acid or red oxide of mercury; which immediately % TC's
became brown, and gradually changed to black. Thesolution
tooacquired a deep brown tint. In this state it was still acid,:
gave a blue colour to a solution of sulphat of iron, and precipi-
tated glue; butit contained no mercury. |
I boiled this liquor on a fresh quantity of oxide; when it
became clear, colourless, and no longer contained either tannin
or gallic acid.
Pari of the oxide of mercury was reduced: the rest was mix-
ed with concrete phosphoric acid [so the original], but nothing
was sublimed from it by the action of lead.
If charcoal previously purified be employed instead of red With charcoal,
éxide of mercury, the solution of gallic acid loses almost entirely
its taste and colour; the liquor becomes green, and’ no longer
precipitates glue; but it still gives a violet blue tint to solution
of sulphat of iron. Boiled with a fresh quantity of chafcoal,
the liquid becomes colourless, and no longer produces, any
change in the solution of glue or of sulphat of iron, After it is
evaporated to dryness, a brown matter remains in the capsule,
which precipitates acctat of lead of a dirty gray,.and nitrat of
mercury and muriat of tin yellow ; sq that we may consider it
as extractive matter,
These experiments prove, that there exists no process for Only tobe
purifying Scheele’s gallic acid but sublimation; unless the pio- etree
portion of oxide of tin employed by Mr. Berthollet, which
he does not mention, has a great influence on the result, Yet
the mode of purifying the gallic acid by-sublimation cannot be
adopted, if we wish it to retain all its properties. The different but this alters
characters exhibited by the two acids will afford proofs of this Bie, Sadie ‘A
assertion.
ge Bgl 901 of the crystallized and sublimed Gallic Acids.
Scheele’s crystallized acid imparts to water a slight lergon co- Solution of the
lour: this solution grows deeper coloured by the action of the bc
air: it reddens tincture of litmus: limewater procuces in it a
blue colour, which changes to that of peach blossoms ifthe lime-
: : ue o, .: with hme
water be in excess, and on adding a few drops of nitric acid toy ate,
afose colour. The same phenomena take place with water ofbarytes,
ef barytes. This
64 WISTORY OF THE GALLIC ACID.
alkalies, _ ‘This solution takes a colour more or less green with carbonat-
of soda, but isnot changed by carbonat ofammonia, Caustic
potash changes it to a deep brown; and ammonia to a reddish
brown.
aitphat of iron, With green ae of iron it is a violet blue, which is constant,
ey of mer as an excess does not alter it. With nitrat of mercury it gives
acetat oflead, a yellow precipitate; with acetat of lead, and muriat of tin, a
muniat of tin, whitc.
oxigenized mu-,_ The solution of this acid is not altered in appearance by ox-
caguetoepnin igenized muriatic acid.
and glue. . With glue-it gives a copious precipitate.
Richter’sacid. | ‘The same experiments were made with the acid obtained by,
‘Richter’s process, and the results were similar, except that the
. precipitate thrown down by glue was very abundant.
Solution of sub- Sublimed acid of Deyeux. The solution of this acid by hot
hinedaeidy ater cmits an aromatic odour, and a slight oily pellicle i is per-
ceptible on its surface.
This solution becomes brown by exposure to the air. It
with lime- faintly reddens tincture of litmus: limewater gives it a colour
arc: of wine lees, which an excess of it converts to a fawn colour.,
With barytes we obtain the latter tint, and the liquor is imme+
' diately covered with an oily pellicle.
catbonated - Carbonat of ammonia produces no change In the acid ine:
— that of soda gives it a fawn colour.
pure alkalies, . Caustic potash browns it considerably: with ammonia the
. ciated is lighter. ;
sulphat of iron, Ifa few drops of a solatiorof sulphat ” iron be dropped
into this acid liquor, a blue colour is produced, which soon
changes to a violet blue. Frequently however, instead of a blue
tis? colour, we have a deep green. ‘This no doubi depends on some
; peculiar circumstances: and I conceive it may be, attributed
to the degree of oxidation of the iron; for with muriat of iron
at a maximum we have constantly a green colour. This effect
is less striking with other acids: the infusion of galls, made
, + without-lead, always retains its pure blue colour.
With nitrat of mercury the precipitate is blackish: ist
nitrat of mer- acctat of leadis fawn coloured, and very light.
a acetat of ‘The sulpkats of zinc and copper, and mutiat of tin, produce
other metallic no change.
re Oxigen-
!
HISTORY OF THE GALLIC ACID, 65
Oxigenized t muriatic acid browns the solution of gallic acid, and oxigenized
and an excess deprives it of colour. [ ORL
*On- comparing the difference of the effects of these acids, it
will be easy to appreciate. them.
The sublimed acid has less acidity: it is decomposed by the bi emer d
air: ithasnoaction on barytes, carbonat of ammonia, or muriat with the one
of tin. The precipitate obtained with nitrat of murcury is black- *#llized.
ish, instead of yellow: that with acetat of lead is slight and
fawn coloured, instead of copious and white.
Oxigenized muriatic acid browns atransparent and colourless
solution of the sublimed acid, while it does not alter the colour
of-a solution of the crystallized.
~ Lastly the sublimed acid does not constantly produce the same
colour with sulphat of iron, and does not precipitate glue.
If it be easy to point out the characters that distingu'sh these Bot Bey to ace
. two acids, it Is difficult to explain whence their difference arises. differences,
Mr. Berthollet has justly observed, that Scheele’s acid, when
not purified, contains a great deal of tannin; and that, when
purified by oxide of tin, it does not percipitate glue.
“As to that of Mr. Richter, I havealready pointed out its ana-
logy to Scheelés: yet both these acids appear to me to differ Sublimed acid
from that obtained by sublimation. The latter contains a small vate a, ee
quantity of volatile oil, which is combined with it; and which
by the action of caloric assumes a character approaching to that
of oils rendered resinous. ‘This property may be ascertained by
dissolving the sublimed acid either in alcohol, or in ether; for if
the liquid be evaporated by rubbing it on the skin, we shall ex-
perience an effect similar to that promaned: by a resin dissolved in
alcohol.
‘It is not without difficulty, as may be supposed, that we can
attain a complete knowledge of the nature of the gallic acid. What is the
Does this acid exist in galls already formed? May we consider S#lic acid?
it as a peculiar acid ; or rather is it merely the result of the com-
bination of a vegetable acid with tannin, extractive matter, and
other substances existing in galls? These are questions, that yet
remains to be solved. I have attempted by a series of experi- .
ments to add some facts to those that are known; and if they do
not yet lead toa complete solution I conceive some new results
- will befoundin them, which serve to explain the ‘nature and be Sieh
— of the gallic acid.
Vox, XVII.—Juwne, 1807. F Exanis
66 HISTORY OF THE GALLIC ACID:
Examination of the Action of Caloric and of Water on Nutgails:
Action of Caloric,
Action ofeal- Mr. Deyeux having examined ina particular manner all the
oie products of the distillation of galls on a naked fire, I shall con-
sider only the acid liquor obtained from them.
Properties of The process was conducted in the manner indicated by that
a ae chemist. The fluid in the receiver was aromatic, a little milky,
very acid, did not precipitate glue, and gave a violet blue with
sulphat of iron, which changed to a dirty green. Lime and
barytes produced a peach-blossom colour. Nitrat of mercury
threw down a blackish precipitate; acetat of lead, and muriat of
tin, a white.
Saturated with Having saturated the acid liquor with potash, I obtained by
potash, ; f : Caley iti
gave signs of Vaporationa brown empyreumatic matter, whichon the addition
acetic acid. of sulphuric acid emitted a pungent smell resembling that of
acetic acid.
Action of Water on Nutgalls.
Gall macerated Galls finely powdered being shaken in cold water for four
in: WBteE, minutes, the liquor, when filtered, was of a golden yellow
colour. One part was distilled in a retort on a sand heat:
the other was saturated with carbonat of soda.
Distilled gave . The produce of the distillation was a clear, colourless, and
occ. slightly acid liquor, ¢hat precipitated neither glue nor sulphat
of iron,
Saturated with ‘The liquor saturated with the alkali was evaporated to dry-
Stage aea ness; and the residuum being dissolved in distilled water,
aidded and dis- sulphuric acid was added till it was a little in excess, when
MIEGs the mixture was distilled in a retort. The products were ex-
amined in succession. First a fluid came over without taste
or smell: soon after the liquor was acid, but contained neither
sulphuric nor gallic acid.
With boiling T made a similar experiment with boiling instead of cold
mart water. The liquor remained turbid, though filtered. Being
subjected to distillation, and combined with soda, in the same
manner as the preceding, I obtained the same results.
aa
These
/
HISTORY OF THE GALLIC ACID. 67
Yhese experiments suggested to me the existence of a acid A free acid in
. ean ah. Pt. ae Balle,
veady formed in galls, and the possibility of obtaining it by
distillation.
Accordingly I heated to ebullition in a common alembic a Obtained by
kilagramme [2lb. 30z. 6dr. avoird.] of galls coarsely powder- bee wich
ed, with double the weight of water. The distilled liquor, as
Mr. Deyeux observed, was a little milky, aromatic, and on
standing deposited a little floculent sediment. 1 changed the
teceiver, when about two thirds of the liquor had come oyer,
and I continued the distillation till it became coloured.
The first product was acid; reddened tincture of litmus; 1st. product.
and had no action on lime or barytes water, nitrat of: mercu- .
ry, acetat of lead, sulphat of iro, or glue.
‘The second product was turbid, coloured, a little empyreu- 2nd. product.
“matic; its acidity was more marked; and it precipitated the
metallic solutions above mentioned, but did not act on glue. we
Each of these acid liquors was saturated with potash. The Saturated with
first yielded a foliated salt, which, on the addition of sulphuric P°*S
‘acid, gave out a smell of asetic acid. Part of this salt was
dissolved in distilled water: the excess of its base was accu-
rately saturated by nitric acid, and nitrat of mercury at a
minimum was added to the solution; when a precipitate was Proofs of the
formed, which had all the characters of acetat of mercury. aan oe the
‘To convince myself still farther of the presence of acetic acid,
{ treated the neutral acctat of potash in the same manner, and
‘it afforded me ‘the same results. +
The second product was saturated with potash in the same 2nd. product
‘ ae ’ ae! afforded simi-
manner. The liquor became very brown: a slight pellicle jay proofs.
formed on the surface, which increased during the evapora- |
tion: the-saline matter was highly coloured and empyreuma-
tic. Being subjected to the same trials as the preceding, simi-
Jar appearances were observed,
These experiments leave no doubt of the presence.of acetic The acetic
acid in galls: they prove, that it may be obtained by distilla- ey
tion with water; and that caloric, when it acts more directly by means of
on this acid, facilitates its combination with a small quantity neue cao
. : 2 4 . ined With an
of empyreumatic oil, and perhaps with a little tannin, the enpyreumatie
spresence of which is not demonstrable by glue: but as this saga ee
diquor acts on sulphat of iron in the same manner asthe sub- “" ue
F2 limed.
68 HISTORY OF THE GALLIC ACID.
and with aro- }imed acid,.we must presume, that there is a kind of analogy
pi Peet: in their composition; admitting however this difference, that
reumatic, when the sublimed acid contains no empyreumatic oil, but a partie
nik vik cular aromatic volatile oil.
This oil may be detected by dissolving the acid in very pure
sulphuric ether, and adding a little water, when a few drops of
oil will be seen floating on the surface, which disappear on
shaking the mixture.
@austic potash. If a concentrated solution of caustic potash be employed
instead of water, a white, milky substance is separated, which
requires a large proportion of water to dissolve it, but the li-
quor still remains turbid.
‘The oil shown.
The ethereat This ethereal tincture yields a fine blue colour with sulphat
tincture, ; .
of iron.
and its resi- Evaporated in the open air it leaves a shining substance,
oF very acid, separating in scales, and having the appearance of a
varnish,
The same phenomena take place, if galls be digested in
ether; but the substance contains tannin in addition.
\
Examination of some earthy and alkaline gallats.
Farther proofs. Though it appears to be demonstrated, that acetic acid ex-
of acetic acid ists ready formed in galls we cannot too much multiply proofs
in confirmation of its presence ; and to demonstrate, that this
acid, combined with other substances, constitutes the gallic
acid.
by forming dif, | With this view I formed gallats of lime, barytes, potash, and
ferent gallats. soda, These neutral combinations afforded a violet red colour
with a solution of sulphat of iron, and scarcely precipitated glue
while the acid employed had the property of forming with it a
copious precipitate, On these salts dried I poured some very
weak sulphuric acid; I distilled them with a gentle heat, and I
always obtained acetic acid.
The residuum ‘he retorts contained a very deep brown matter. I crystale
arnt eh lized the salts that were preceptible of it, and obtained sulphats.
5 The supernatant mother-water had the property of slightly
browning the solution of sulphat of iron; but this appearance
does not prove the presence of gallic acid, for the black colour
of the mother-water was sufficient to give it this hue.
If
#ISTORY OF THE GALLIC ACID, 69
If one of the gallats, that of soda for instance, be treated with Gallats treated
charcoal, the tannin will be entirely destroyed, so that the solution Nags we =
will no longer precipitate glue; and after repeated boiling with
fresh portions of charcoal, it will no longer act on sulphat of iron,
* The liquor being afterward evaporated to dryness, and distil. sa give acetic
led with very weak sulphuric acid, we still obtain acetic acid, F
* { shall not insist any farther on the possibility of obtaining
acetic acid by decomposing gallic acid. I might mencon the
experiments, which would tend to support the preceding, but
entering too minutely into these particulars would add nothing
to the facts I have already adduced.
T shall conclude. with an experiment, which appears to me Examination
important. The object was, to establish the nature of the elastic nie
fluids resulting fromthe complete decomposition of the gallic decomposing
acid by heat. Mr, Deyeux has announced, that he obtained a,
only oxigen gas, and carbon. Mr. Berthollet, who repeated the
experiment, says, that he had no oxigen gas, but constantly car-
bonic acid.
These results, of which no other vegetable acid furnishes an
example, could not avoid exciting the attention of chemists,
In fact itis difficultnot to admit hidrogen in the composition
of gallic acid; and Mr. Fourcroy has expressed his doubts on
this subject in his System of Chemical Knowledge, but the
question is not yet decided by experiment. a
In consequence I heated gallic acid ina retort. The fire
was gradually raised till the retort was red hot. During this'ac-
tion of caloric I obtained several jars full of elastic fluid. The The first por-
first contained only atmospheric air; the others carbonic acid fendsoWs
gas: at least the gas had all the characters of thin acid; but terward carbo~
the phenomena that occurred during the decomposition of the DEO Ss
gallic acid led me to suspect, that, if any hidrogen gas had been
evolved, it could exist only in a very small quantity. | didnot
satisfy myself therefore with the trial by limewater, and the ex-
tinction of a taper in the gas, Having perceived, that hidrogen mixed with
gas mixed with.agreat deal of carbonic acid gas cannot be fried, seinen
because this acid acts too promptly on the flame of the taper,
] passed a little caustic potash into the last jar of gas; agitated
it, absorb the carboni¢ agid; and then immersed a taper in the
residual gas, which barnt with fame, and thus afforded mea
proof of the presence of carburetted hidrogen.
The
70
Base of gallie
acid, hidrogen
and carbon.
Acid of Scheele.
Sublimed acid,
not a modifica-
tion of the
gallic.
Acetous the
only vegetable
acid,
forming others
by various ad-
ditions inti-
mately combi-
ned with it.
Instances,
HISTORY OF THE GALLIC ACID.
The gallic then, like other vegetable acids, is eompossed of
oxigen, hidrogen, and carbon. If but a small quantity of hi-
drogen, can be obtained, it is because water is formed during
the decomposition of the acid, so that the hidrogen passes over
only when very little oxigen remains to.act on the carbon. —
I have attempted to shew, that the gallic acid is a compound.
Its formation by Scheele’s process appears to me to favour this
opinion. In fact, if the quantity of acid extracted from the
aqulous infusion exposed to the air be compared with that a&
forded by sublimation, I conceive it is not difficult to account °
for the increase. There can be no doubt, that acetic acid -
med in the liquor, which, acting ona portion of tannin and ex
tractive matter, constitute the gallic acid of Scheele: but thiscom
bination is rendered more intimate, and somewhat different, by the
action of caloric; of which we have a proof when. the acid is
obtained by sublimation, for not only is the tannin decomposed,
but the acid remains combined with a volatile oil which is for-
med. Perhaps this acid contains a small portion of tannin im
very intimate combination, whence no.doubt arises its property
of giving a momentary blue with sulphat of iron, though its pre-
sence cannot be demonstrated. This acid then must have dif-
ferent properties from that of Scheele: and if it were possible to
assimilate it to other vegetable acids, the benzoric would it be
that, which it would have the greatest analogy. May it be con-
sidered however as a modification of the gallic acid? I think
not. Itis the same with other vegetable acids: and it 1s prebable,
that there exists no modification of them. ‘The acetous appears
to be the sole vegetable acid: it desolves and retains in various
proportions a number of the immediate products of vegetables,
and in tye processes ta which we subject vegetable substances,
we facilitate its combination in a more Jntimate manner; and
frequently even augment the quantity of this acid. Already
several chemists have admitted the possibility of the acetic acid’s
dissolving and remaining combined with fixed andempyreumatic
oils, and animal matters; they have even gone so far as to imi-
tate acids of this sort. The formic, pyrolipic, pyrotartarous,
and pyromucous, have been classed by Messrs. Fourcroy and
Vauguelin among the compound acids: it is the same with tha
lacti¢,
HISTORY OF THE GALLIC ACID. 71
lactic, the composition of which was pointed out at the same
time by those chemists, Mr, Thenard, and myself: lastly we
have preof too, according to Mr. Thenard, of the existance of
this acid in the urine and sweat, as well as in the sebacic and
ozonic acids. 1 might farther add to these observations (if we
were not persuaded, that the acetic acid is found every where)
that it exists in the vegetable as in arfial matters, where it is
almost always in siate of combination ; and that, an equilibri-
um in the proportions being once established, it gives rise to com=
te pounds: hitherto unalterable, and the affinity of which cannot
be destroyed, but by reducing them to their primary ebements,
oxigen, hidrogen, carbon, and nitrogen.
From the facts announced in this memoir it follows:
Ist, That the gallic acids of Scheele and of Richter differ essen- Recapitulatien,
tially from that obtained by sublimation; and that the crys-
tallized is preferable as a reagent, on account of the constant
uniformity of the colour it gives with iron.
2ndly, That this acid appears to be composed of acetic acid,
tannin, and extractive matter; and that it cannot be com-
pletely freed from tannin by crystallization.
3dly; That the acid obtained by sublimation contains no
tannin, at least that can be ascertained by acting on glue;
and that it cannot, on any occasion, supply the place of ay
crystallized acid.
4thly, That the sublimed acid, appears likewise to be com-
posed of acetic acid, united with a peculiar aromatic vola- _
tile oil.
5thly, That by means of water, poured into the ethereal tinc-
ture of galls, or ether containing the sublimed acid, an oily
Matter is separated,
6thly, That there is no process known for purifying Schecle’s
acid completely: that is to say, we cannot take from it the
whole of its tannin, without reducing it to the state of acctic
acid; which proves, that theyportion of tannin it retains is
necessary to constitute gallic acid, and that to this are owing
its excellent properties in the art ols dying.
7thly, That the red oxide of mercury, and oxide of tin, as
well as carbon, decompose this acid.
“ Sthly, That by distilling galls with water acetic acid may be
obtained 3
72 WATER OF THE SEA.
obtained; and that it is by the assistance of caloric acting
more immediately on galls, that a more intimate union between
the acid and the tannin is effected.
gthly, That the earthy and alkaline gallats likewise afford
acetic acid by their decomposition, a
10thly, and finally, That gallic acid, like the other vegetable
acids, is. composed of oxigen, hidrogen, and carbon.
If these results be accurate, we may conceive it possible,
to accomplish its synthesis; or some trials that 1 have already.
made give me the hope of succeeding in it. I shall do
myself the honour of imparting the farther results of my in-:
quiry to the class, if they should be worthy its notice.
Sr ee
XI.
Observations on the Soda, Magnesia, and Lime, contained in
the Water of the Ocean; shewing that they operate advan-
tageously there by neutralizing Acids, and among others the
Septic Acid, and that Sea-Water may be rendered. fit for
washing Clothes without the Aid of Soap. By Samus. L.
Mircui xt, of New York. ‘i
‘Continued from p. 392 of Vol. XVI.)
Observations I FIND on experiment that carbonate of soda thrown into
and facis re- ocean wat : : 7 . 2
specting the C°#” Water, immediately renders it turbid, the lime and mag-
component hesia instantly turning milky on their disengagement from
ee thejr respective portions of acid. To make the water fit for
and the useful washing, so much soda must be added. as not only to effect a
pplication of complete precipitation of these earths, but to render the water
’ sulficiently lixivial or alkaline, ,It will then exert its deter-
gent and purifying powers. pin
Having entertained doubts at first, whether the water ought
not to be decanted of after the lime and magnesia had settled
to the bottem, or whether it would not re :
3 quire straining or
filtcying to render it fit for use, I convince
d mysclf by experi-
r ment
WATER OF THE SEA. 7S
‘
ment that foul linen could be rendered clean and white by Observations
and facts re-
being washed in alkalized’ ocean water which contained its Gpeatine the
whole quantity of precipitated earth diffused through it. 1 component
rather think the small quantity of those impalpable and whit ee,
particles which adhere to the linen worn upon the body will and the useful
applications of
be advantageous and wholesome, as the shirts and other gar- that guid.
ments will thereby be enabled to neutralize a portion of the
acid and oftentimes noxious matter formed from the sweat and
other excretions of the skin, &c. Thus they will be rather
serviceable than otherwise, and as both are in their carbonated
state (having borrowed fixed air from the soda) they cannot
do any harm. .
The . general inferences from the whole of the preceding
reasoning are these: 1. Alkaline substances, such as mag-
nesia and more powerfully lime and soda, are plentifully dis-
tributed through the ocean, to keep it from becoming foul,
unhealthy and uninhabitable, which doubtless would be the
case if the sulphuric, septic, and muriatic acids abounding in
it were not neutralized. 2. Where either of these acids is but
imperfectly saturated, as happens when they are united with
magnesia and lime, they decompound. soap, let loose its grease,
and become unfit for washing by aid of that material. 3. If
soda or barilla is added to occan water in sufficient quantity
and the water lixiviated or alkalized, the earths will of course
be precipitated and the acids neutralized. 4. In this state,
dirty linen may be cleansed in it; and men at sea be thus
enabled to have their clothes washed without the aid either a nie wen
soap or of fresh water. 5. For this purpose, a quantity of
barilla or soda should always be provided as an article of the
ship’s stores, and issued to the men on washing days. 6. Thus
by the operation of this alkaline salt, a great proportion of the
nastiness and infection bred in the clothes, bedding and berths
of persons at sea might be prevented, and the crews and pas-
sengers so far preserved from fevers and dysenterses. - 7.
No more room would be occupied by water casks in the holds
of vessels, than at present. 8. The small quantity of magnesia
and lime adhering to clothes washed in this way, is an advan-
tase over and above what takes place in using fresh water,
And-9. A broad and _ noble view is opened of the economy of
Providence in distributing alkaline salts and earths, so liberally
~ throughout the terraqueous globe.
7%
Improvement
ef waste lands.
AGRICULTURE.
bw Wis
An Account of the Improvement of an extensive Tract of —
Land*. By Ricnarp Pues, Log.
SIR,
ly the year 1804 the waste lands in the township of -
Bron-y-garth, in the parish of St. Martin in Shropshire, were
divided and allotted by an agreement entered into by the pro-
prietors of land, without any application to Parliament.
- This township is separated from the county of Denbigh
by Offa's Dyke, the boundary in ancient times between the
kingdoms of Mercia and Wales: the boundary here, as in
other uncultivated parts of the demarkation, still remains
entire, after a lapse of 1000 years. ‘ Upon the ground,
where the improvements detailed in my paper to you are
made, the descendants of the ancient Britons fought for
their independence, and for what remained of their ter-
ritories. Upon this spot the bands of Henry II. headed
by that monarch himself, were foiled in the battle of Ceiriog
by Owen Gwenydd, at the head of his brave Welshmen.
The-township on the west of Offa’s Dyke, is called Crogen,
i. e. a place of graves, because there the slain, who had
fallen in battle, were buried. The posterity of the two,
once hostile nations, now contend which shall excel most
in the arts of peace. This rude soil is now no longer fer-
tallized by the blood of warriors, but by the united labours
of Englishmen and Welshmen. The dyke is still pretty
accurately the line which separates the two languages:
Welsh is generally spoken on the western side; English on
the eastern. The hills, of which these wastes form a part,
are at least as high as any.in the county. Mr. Archdeacon
Corbet, in his account of the agriculture of the county of
Slop, asserts, that the hills near Oswestry are the highest
in Shropshire.
The lands in question are part of the same chain which
composes the skirts of the Berwyn, a mountainous ‘tract,
extending ‘widely over the west of Denbighshire, and the
contiguous part of Merionethshire. As a traveller ap~
* Society of Arts, 1796.
proachgs
P AGRICULTURE.
itis this country from Shrewsbury, a line of highly ™
‘elevated ground presents itself to his view, extending from™
near the Severn to the neighbourhood of Wrexham. This
ground once formed the ,rampart of Wales, though now
cultivation in several of its parts is softening the roughness
of its aspect.
The continuity of the line of hills is broken by two prin.
cipal valleys; the larger is that of Llangollen, through
which the Dee flows: the other is watered by the stream of
the Ceiriog. One part of the Bron-y-garth enclosure looks
over the last-mentioned valley, and has a northern aspect;
the other looks to the east, over the plains of Shropshire.
Lime is found in every part of the line which divides the
mountains-from the plains, on the frontier of North Wales.
The beds of lime-stone in some places lie on sand-stone,
and in other places are found belowit. In others again the
Iime-stone is near the bottom of a hill, sand-stone occupies
the middle space, and lime-stone is again found upon the
summit.
In some respects the Aridsice works well, and is of a
superior quality, as the aqueducts over the Dee at Pontey.
syllty, and that over the Ceiriog at Chirk, sufliciently prove.
The sand-stone in the quarries, which furnished materials
for building these aqueducts, is perhaps equal in beauty and
durability to Bath or Portland stone; and the lime-stone,
at least in one quarry near Oswestry, becomes a beautiful
black marble. In the lands, spoken of below, the lime-
stone supplied me with manure, and the sand-stone forms
the larger portion of my fences.
The paper, which accompanies this letter, is drawn up
in haste, because it was only very lately that I deter-
mined to be a candidate for the votice of your honourable
Society. But all the paris are faithfully and accurately
—_
Iam, Sir,
Your most obedient Servant,
RICHARD PHILLIPS.
Fyn-y-Rhos, near Oswestsy,
January 1806.
To C, Taytor, M.D.
1D
inpperneak
e lands.
16
Improvement
of waste lands.
AGRICULTURE.
An Account of the Improvement of more than Ninety Acres
of Land lying waste.
In the‘year 1804 a large quantity of waste land was di-
vided and allotted in the township where I live, on the bore
‘ders of ‘North Wales, by private agreement. I became
possessed, as proprietor, of seventy acres of these lands. I
obtained fifty acres more by two leases, each for twenty
one years.
' The wastes consisted of two divisions, The first was a
piece of common land, surrounded by old enclosures. This
portion, though raised far above the general level of the |
country, is much less elevated than the larger tract here
after to be described.
~ The portion of this waste allotted to me was eight acres,
The grass produced, while the land was in its natural state,
Was a sour rough sort. It afforded pasture in the summer
toa few cattle, horses, and sheep. The coldness of the
soil, and the consequent bad quality of the grass, gave this
common the Welsh name of Rhos, a name which implies a
tract of moist land, producing a coarse sour herbage.
1. I began my improvements upon this allotment, because
it lay near my house. The fence is a bank four feet high
from the bottom of the ditch, with a double rail at the top,
A double row of quick is planted upon the top of the fence,
to supply the place of the rails when they decay.
The surface soil is about six inches deep, with a substra.
tum of bad yellow clay. The first ploughing was in June
1804. It was cross-ploughed and harrowed in August;
ploughed a third time about the 20th of September; ma-
nured about the end of the same month with one thousand
six hundred and ninety- bushels of lime, amounting to about
two hundred and eleven bushels-an acre; ploughed a fourth
time in the middle of October, in small butts or ridges ;
sown and harrowed. - This operation of ridging was pecu-
Jiarly necessary here to carry off the surface water, which
had’ formerly greatly injured the land. -~ ‘Twenty-four
bushels of Devonshire wheat were sown: the return was
about two hundred and forty bushels (thirty bushels an
acre). The crop was one of the finest in the county.
The expences, aS appear by the subjoined table, were
&. 88,
AGRICULTURE: ay
#. 88 19s. 1d. The wheat was worth last month . 130. Improvement
The balance in my favour is €. 40 Os. 11d. (4.5 2s. 7d. an % ¥4ste lands.
acre). This land in its natural state was not worth five
_ shillings an acre. When it is laid down in grass it will be
worth 40s. an acre.
In the beginning of October 1805, the stubble was har-
rowed off, and conveyed to the farm-yard. The land was
then ploughed, sowed with twenty-four bushels of - wheat,
and harrowed as the year before. This is not my usual
course of crops; but it was thought that old common land
could not very easily be exhausted, and I was tempted to
take another crop of wheat by the high price of corn, and
by the circumstance of the land being for four years tithe
free. The corn now, the 12th of January, is coming up
in abundance.
It is. my intention to lay down this lot with grass wei to
be sown with oats in the spring of 1807. Oats I conceive
to be the best grain for the next crop, because the land is
not dry enough for turnips and barley.
The second, and much larger, division of lands isi
waste eolaiied along the side, and reaches the summit of
a hill, which is equal in height to any inthis county. ‘The
_ aspect is, for the most part, north and north-east. A
mountain torrent runs through the midst of this tract: some
of the lands on one side of this torrent are more sheltered,
and have a southern aspect.
____ Lime-stone is found on the lowest part of this waste, not
far from the bed of a river: but the steepness of the ground
above would have been too formidable an obstacle to the’
cultivation of the higher lands, had not lime-stone been dis-
covered upon a spot so elevated, as to enable the improver
to convey his manure, at a comparatively a expence, to
the lands below.
“The coals indeed, for burning the lime, are brought up
a steep hill, a distance of four miles. The ascent up which’
they are conveyed, enhances considerably the pest of
the manure.
Upon this waste the Jime-stone is at the bottom of the
hill, and fortunately upon the top also. The substratum,
at no great. distance from the surface, is sand.stone, in some
places
78 AGRICULTURE.
Improvement Places hard, in others loose, and less useful for fencing; 4
of waste lands. purpose to which I have applied it in dividing most of the
enclosures. ;
All the waste lands allotted to me as proprietor, or occu.
pied by me as tenant, in consequence of the two leases men.
tioned above, were covered for the most part with gorse,
(Ulex Europzus,) in some parts of England called furze.
Some more favoured spots produced fern alone; and others
were much encumbered with stones. The stones were
earted off the lands to assist in making the fences; and
those, which were too small for this purpose, were used to
fill up large holes in various parts of the land. 3
The thin soils upon these wastes seems to have been cre-
ated by the annual decay of portions of the gorse; a plant
admirably calculated to produce, and afterwards to detain,
in spite of rains and storms, the vegetable earth upon these
steep declivities. Around each bush of gorse is always
found a heap, more or less high, of excellent soil; and so
completely do the prickles of this plant defend the grasses,
that grow among it, from the attacks of sheep, that the
earth, produced by the successive decay of vegetable matter,
accumulates, and renders lands, which a few centuries ago
would probably have been unproductive, proper for the
growth of corn. |
It is impossible to traverse our mountains without observ-
ing how wisely these things are contrived by Him who pro-
tides for us all.
The highest mountains of North Wales, where the rock:
does not every where appear, are clothed with heath. As
ages roll by, the soil, produced by the annual decay of por-
tions of the heath, becomes fit to produce gorse. If the
water has a ready fall, and the land is dry, gorse appears in
abundance on the more exposed sides of the* mountains.
Where soil has accumulated in sufficient quantities, the next
protector and fertilizer of the mountains is fern. Where.
ever this plant flourishes, still richer quantities of vegetable
earth are every year added to the surface soil, and the ground
is rapidly prepared for the plongh..,
Let me be excused for having made this dlgresstoy longer
than I intended.
T now
AGRICULTURE.
!
_ Tow proceed to state the operations performed upon
the second portion of waste land improved by me.
2. One close of 21 acres, for which havea lease for 21
years, at 10s. an acre, is no stecp, that no waggon or cart
can be used, to carry off the crop; drags must be employed
for this purpose.
This Jand was so steep, and was incumbered with such a
quantity of stones, that a respectable gentleman farmer,
whose lands are contiguous to it, and to whom it was of-
fered in exchange for other lands, declared he would
not cultivate it if it were given him as a present. I should
observe, that it was stipulated in my lease, that the landlord
was to be atthe whole expense of fencing.
The greater part of this land was begun to be ploughed for
mein December 1804 by a neighbouring farmer at 20s. per
Improvement
of waste lands.’
acre. It was at first ploughed one way. The steepness of
the ground made it necessary for the horses to-drag the
unencumbered plough to begin the furrow again upon
the ‘¢ vantage ground.” Two acres of it could not
at first be ploughed at all. Hand labour was here em-
ployed.
The difficulty of ploughing proved so great, that 1
thought it right to make some addition to the stipulated
price of 20s, anacre. It was harrowed in June 1805. The
whole of the field was cross ploughed in July; harrowed
and manured in August with 5200 bushels of lime, about
- 250 bushels an acre. The quantity of lime generally used
in this country is about one-fourth less than this, The
lime was carted in small quantities, and laid upon the land
_ with the assistance of three men with each team. So many
men were necessary. on account of the unevenness of the
. ground,
The fence, made at my landlord’s expence, consists of a
wall six feet high, 20 inches broad at the base, and 14 at the
top. It is to be pointed next summer with mortar. The
materials were partly stones collected in the field and partly
sand-stone obtained from a quarry, opened for this purpose
in an allotment to be described hereafter. The fencing is
mentioned in this place, because it was in this part of the
- process that the stones were collected off the land. The land
was
80
Improvement
ef waste lands.
AGRICULTURE.
was ploughed a third time the first week in October ; sowed
with wheat, and harrowed. Three plonghings were dowalst
sufficient for this land, because the soil is light and ragged.
The depth of soil is here near eight inches. Thesubstratum
is a light yellow rammel, called in this country cat-brain.
The sand-stone, which lies next below, does not appear near
the surface, except in one small part of this field. The
wheat sown was 71 bushels, above three bushels an acre.
This large quantity of seed was thought necessary, on ac-
count of the lightness of the soil, and the exposed northern
aspect. These plants now (January 12) look healthy; they
are of agood colour, and equal in appearanceand promise of
x good crop to the wheats upon the best lands in the neigh-
bourhood.
3. I obtained a like lease for 21 years of another lot of
12 acres from the same landlord at 10s. an acre. I may here
remark, that by an errorin laying out aroad, nineand a half
acres of this field belong to my landlord, the other part to.
meas proprietor. But the close is at present undivided, and
the whole subject to the same management. The aspect is.
here §. E.; but the situation is much higher than that of
the last mentioned lot.
This lot, like the last, was, by the terms of my lease, to be
fenced by the landlord; but all the fences have been made
under my superintendance. The whole fence would have
been a wall, but the sand-stone rock on this part of the hill
failed. Twenty-six roods are fenced with a stone wall, six
feet high. Sixty-seven roods are fenced by a bank and
ditch, faced on the one side with stone, and protectedabove by
posts and double rails. Upon the top of the bank hawthorn
quick is set. Fifty-eight roods more, which complete the
enclosure, are bounded bya very high old dyke. This
boundary, however, is of such a sloping form, that
some additional defence was necessary. A ditch is there.
fore sunk on the summit of the dvke, to the depth of
five fect; in this are planted strong staggers, as they are.
here cabled consisting of hazle, holly, thorns, and horse
briers.* ‘
*So called, perhaps, because they are an excellent fence, when
mixed with other underwood, against horses as well as sheep, and,
ether animals.
The
ens Vhelos Journal. Vol XVI pl.2.p.80.
Ne 2
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Nicholoons I hules, Journal, Vol XVI pla p Lo.
leastory, MD.
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_. AGRICULTURE.
The first ploughing was in February 1805: it was done
by my own teams. We used four horses in each team.
I will remark here, by the way, that my own teams
ploughed, the first time over, all the lands which I have
improved, except the last mentioned lot of 21 acres;
and that the expence for oats only given to my horses the first
nine months of my improvements was 70/. This lot was
harrowed the beginning of June. The second ploughing was
in July by hired teams; it was harrowed the second time in
the beginning of September; limed with 3250 bushels of
lime, allowing about 270 bushels to each acre. It was
sown in the middle of October with 40 bushels of wheat, and
harrowed. The wheat plants are come up in abundance, and
look as healthy and promising as wheat on any lands, in the
country. :
It has already been remarked, that upon these light loose
soils, it is neeessary to sow a larger than usual quantity of
seed by the acre. The soil is here about nine inches deep, but
remarkably looseand light. The substratum above the sand
-rock is the same rammel or cat brain, which is found under
most of these wastes.
4. I obtained from another landlord a lease for 21 years of
two other allotments, amounting together to 20 acres. By
the terms of my lease I am to pay no rent for the first seven
years; for the remaining fourteen years the rent is to be
14s. an acre. The tenant is to make the fences at his own
expense.
Sixty roods of the fence round the first of these two
lots, which consists of 12 acres, is a stone wall six feet
high ; 30 roods, a strong ditch and bank faced, as in the
last lot, with stone, and protected above with posts and a
single rail. On the summit of the bank hawthorn quick is
planted. A single rail was here thought sufficient, because
it is a fence between two closes, not been a close and the
Toad. 3
The first ploughing was in September 1804; this was
the first lot after the Rhos above mentioned, upon which
I employed my own teams. It was harrowed early
May 1805 ; cross ploughed in the beginning of June; har
rowed immediately ; limed in the same month with 3250
~ Vor. XVIL.—June, 1807. G bushels
Sst
Improvement
of waste lands.
82
Improvement
-of, waste lands.
AGRICULTURE,
bushels of lime, the same quantity as in the last mentioned
Jot; plows shed a third lime, and sown in the end of October,
and harrowed, The quantity of wheat sown, as in the
Jast Jot, was 40 bushels: The soilis here partly sand upon
the sand rock, and partlya light soil upon rammel. Hand
Tabour was employ ed at a great expense upon a stony part of
thislot, in quantity about threecacres. The wheat plants upon
this lot are of as promising an appearance as upon either of
those above described.
5. The other lot of cight acres, obtained by the last
mentioned lease, is not yet enclosed. The labourers are
now (13 3th January) employed upon the fence. It was
ploughed in January 1805, and harrowed in the same
month. It is now a fallow intended for pease. This lot
would have been prepared for wheat and sown; but lime,
in sufficient guautitics for all my improvements, could
not this year be obtained, at the only rock from which
‘it could be conveyed at any reasonable expense to these
lands.
I was induced to offer the rents above stated of 10s. and
44°. an acre (in the last case, the land to be for seven years
rent free) because J was confident, that these wastes were
capable of improvement. But in the natural state in which
I found them, they were not worth 2s. an acre. They af-
forded pasture to a few half-starved sheep of the worst .
Welsh breed ; and the sheep did more damage to the fences
of the old enclosed lands in winter, and to the lands them-
selves, than could be compensated for by the profits which
their owners derived from them.
The closes now fenced and improved, are well worth
a guinea an acre. A year ago they were not worth two
shillings.
The improvements upon the first four lots, above de-
scribed, are to a certain degree complete. They contain
fifty-three acres of as fine green wheat, as any which this
country contains.
6. A sixth close of thirty-two acres, allotted to me as
proprietor, is fenced with a wall six feet high, and one
hundred and ten roods in length: most part of the wall is
pointed with mortar: on the outside ; the rest is to be
pointed.
a
AGRICULTURE. 83 ;
pointed next summer. The lower part of this allotment Improvement,
is bounded by the fences of my old enclosed lands. On the % Waste lands.
exposed side, towarils the N. W. a plantation is intended,
fifty roods in length, and twelve yards in breadth.
This close was almost entirely covered with gorse. There
was, as ] stated above, much of this plant upon'the lands
already described. My first operation was to stock up the
gorse. I gave my labourers three guineas for this work,
upon this lot only. They were also to have the gorse for
their own use, which was partly uscd‘for fuel, and partly
sold by them. They sold it at 5s. the cart load. I made
an experiment upon five acres of this close, where a plough
could not at first be used. After the gorse was stocked off,
the land was pared and burned; and the ashes were spread.
The plough could, after the land had been thus treated,
though with some difficulty, be used. I ploughed it in June,
1805; harrowed it; ploughed it three times more; and
sowed it, about the end of the same month, with turnip
sced. There is now upon the land a fair average crop of
turnips.
I also pared three acres more. Part of this was burned,
and part was manured with dung. Where the dung was
laid, the ground was trenched about nine inches deep 5 the
sod was placed with the surface downwards within the
trench. The dung was laid in moderate quantities upon
the sod, and covered with about six inches of soil. Pota-
toes were then set in the beginning of May in rows. They
were hoed twice. The produce was abundant.
The remaining 24 acres of this inclosure, were ploughed
in February and March, 1805. Fourteen acres were, after
one ploughing, sown with 71 bushels of black oats; 11
acres with pease; and three acres with summer vetches.
The ground was then well harrowed. TI had littie land of
my old enclosures this year in oats. It was my wish to try,
whether a crop of this grain might be obtained, upon
land so fresh and light as this, without manure, and with
one ploughing. The first promise, however, of the oats,
was so bad, when they began to appear above the ground,
that I thought it best to throw some lime upon the land;
which, if’ not so beneficial to the crop of oats, will be use-
ful
S4
Improvement
of waste lands.
ah
AGRICULTURE.
ful to any succeeding crop. [I therefore manured 18 acres:
viz. all the land where the oats were sown, and part of that
sown with pease, with 4550 bushels of lime. |
I obtained from the 71 bushels of oats, a return of, 360
bushels; a clean, thin crop, intermixed, indeed, with a
little fern. ‘he pease and vetches produced but a poor re-
turn.
In the beginning of November my teams were not much
employed. I sent them to try how this land would appear
when ploughed up, I found the part which had been limed -
remarkably mellow. I conceive that this favourable ap-
pearance, arose from the length of time that the lime had
been upon the ground. _ I then procured several hired teams
in addition to my own. It was all ploughed up by the
twentieth of the same month; sown with 95 bushels of
wheat, and harrowed. ‘The potatoe land was sown with
wheat, at the same time. The six acres, which had not
been limed, are to be manured with 240 bushels of soat.
The soot is now in waggons upon. the ground; and the
first favourable day, it will be thrown upon the land as a
top dressing.
This is the last field sown by me. The wheat plants are
now (January 13) making their appearance aboye ground,
and look well.
~ Lintend this year to proceed with activity in the improve.
ment of the following allotments, which still lie waste.
7. and 8. One of these lots of 25 acres I obtained in
exchange for four acres and a half of old enclosed, arable
land, detached from my farm, of much the same quality,
with other arable lands in this neighbourhood. This circum.
stance alone proved of how litilo value these waste lands were.
These 25 acres were an object to me, as they lay conti,
guous to another of my allotments; and they are equal in
goodness of soil to any upon this hill. After this land has
undergone the process described in lots 2d and 3d, I hope
to see these 25 acres of equal value, acre by acre, to the
four anda half which I gave for them.
These 25 acres, as well as Jot 8, 27 acres, allotted ta
m¢ as proprietor, will be improyed vext summer. ;
9, Three |
AGRICULTURE. . 85
9. Three acres of steep ground, that can never be cui. luprov ement
tivated, will be planted, this spring, with different kinds har oy a
of forest trees.
The tables of expenditure are below. The return in the
first lot has more than repaid all my expences the first year ;
and the return promised by the three succeeding lots, is lit-
tle less abundant.
If I am permitted to live another year, and to enjoy my
usual health, I hope to see 148 acres of land, which was
so lately almost entirely unproductive, covered with golden
harvests, or adorned with thriving plantations.
LOT I.—8 Acres.
1804.° SEL USa is
, 64 roods of fencing, at 7s. per rood - - 22 8 0
1 gate and posts’ - - - - mi ky > OD
1690 Winchester bushels of lime, ee per bu. 17 12 1
Carriage - - - - - - 5 4.0
Ist ploughing, 20s. per acre - - 8 0 0
2d ditto 15s. per do. - - 6 0 0
3d ditto 10s. per do. = thn eae On
Ath ditto 10s. per do. - a" > 48 °0"°O
3 separate harrowings, at15s.peracre—5acres 6 O O
24 Winchester bushels of wheat, at lls. do. 13 4 0
Labour - - - - - a: belOy O
1805.
1 ploughing and harrowing, at 15s. peracre 6 O O
24 Winchester bushels of wheat, atlls. - 13 4 O
LOT IJ.—21 Acres, Fenced by Landlord.
854 roods of stone walling, at 17s. per rood 72 13 4
3 gates, atll. 1s. each - - - OE ae
5200 Winchester bushels of hi at 23d. Pe bus. 54. 3 4
Carriage» - - 10 0 O
Ist ploughing at 20s. Ber acre « ore® 0
2d ditto at 15s. perdo. - - 1515 O
3d ditto at 10s. perdo. = - .10 10 O
3 separate harrowings, at 15s, perdo. - 1515 O
71 Winchester bushels of wheat, atlls. perb. 39° 1 O
Labourers for stocking, levelling, clearing
stones, and spreading lime , - «~ 15,5 2
ee
©
pu
86 AGRICULTURE,
Improvement LOY Il1.—12 Acres, Fenced by Landlord.
ste Jands. bs m
—, 26} roods of stone walling, 6 feet high, at '
17s. per rood : 4 . Per 19? ¢
67% roods of fencing, with stone face, and
double posts and rails, and hawthorn
quick, at 10s. per rood - - 3 HIS FS YO
58 roods of sunk fence, 5 feet deep, and
staggers on thé top along the dyke, at
4s. 9d. per rood ~ : - ad ws lal
2 gates and posts, at 12. 1s. each + ee ar OF
Ist ploughing, at 20s. per acre .~ “ter 0 'o
2d ditto at 15s. per do. - = oy OO
3d ditto at‘10s. per do. - we GO +O
3 scparate harrowings, at 15s. peracre - 9 O O
3250 Winchéster bushels of lime, at23d. per
bushel « eh ae = - 5 WA |
Carriage *- - z . = Peng. a
40 Winchester bushels of wheat, at 11s. per
LE Ny a amelie ee a yam |
Labourers, for stocking, levelling, and’
spreading lime - - - eel gat ee &
LOT IV:—12 Acres, Fenced by Tenant.
60 roods of'stone walling, at 15s. per rood 45 O Q
30 ditto of fencing, with single” posts and
rails on top, with hawthorn quick, at’
9s. 4d. per rood - - “ - 14 0 0
Petey ald poses wel ls. ee ee ee
Ist ploughing, at 20s. per acre - «~pAiZ 0 @
2d ditto at 15s; per-do. so. Sane” OG
3d ditto at 10s. pérdo. —- = & O2rO
3 separate harrowings, ati5s. perdo. -« 9 O O
3250 Winchester bushels of lime, at 2id. per
beaker 2.0/2 « . ° iodine. y
Carriage - - - - - ihe "O
40 Winchester bushels of wheat, at 11s. per
bushel « - - - - 2) 7 2Bi420¢ 0
Labourers, stocking, levelling, clearing,
and spreading lime. - - + - 14°8 6
110
AGRICULTURE. |
LOT VI.—32 Acres. °
roods of stone walling, 6 feet high, at
87
. Improvement
~ 17s. per rood - - = - - 93 10 oO waste lands.
6 ditto of fencmg, at 9s. 4d. per rood - 216 O
3 gates and posts, at 1/. 1s. each. - - 38 3 0
Ist ploughing, at 20s. per acre. -.. - 32 0 O
2d ditto at 15s. per do. - - 24 0.0
2 separate harrowings, at 10s. peracre - 16 O Q
4550 Winchester bushels of lime, at 27d. per
bushel - - - - - - 47 7 11
Carriage - - - - a eS tl
71 bushels of oats, at 3s. 4d. per bushel - 12 7 QO
24 ditto of pease, at 5s. per bushel - ny Be 0.4.0
8 ditto of summer vetches, at 6s. per bushel 2 8 O
240 ditto of soot, at 6d. per bushel - = pO. Ou
Sowing the same, at 5s. per 100 bushels 0.12.90
95 Winchester bushels of wheat, at lls. per
bushel - - - - - - 52 5 O
Paring and burning 5 acres, for turnips,
at 1/. 16s. per acre - - - a 9 O O
2 extra ploughings, at 20s. per acre Oh: ee es
2 ditto harrowings, at 10s. per do. a we QO
Spreading the ashes, at 2s. 6d. perdo. - O12 6
5 pounds of turnip seed, at 1s. per pound O 5 Q
2 hoeings, at 7s. per acre - - Re PSS Wig
150 roods of 8 yards square of stocking, at
1s. per rood, for potatoes - net SE RS
Paring 3 acres, at 12. 6s. per acre = ee
Labourers for clearing the gorse - Ste asin
Ditto levelling and spreading the lime - 515 O
LOT V.—8 Acres, a Fallow for Pease ;
One Acre Waste.
Ist ploughing, at 20s. per acre - lad fi sat
Harrowing, at5s. perdo. - = ie or Ae
Total amount £.1073 1 ©
oe tee
SCIENTIFIC
Observations
by La Marck
on his system
concerning the
influence of the
moon upcn the
weather.
SCIENTIFIC NEWS.
SCIENTIFIC NEWS.
On the Tempest of Feb. 18, which has produced many dreadful
accidents in the Channel.
‘Tne interesting nature of the observations I am about to
communicate, appears to me to be of too serious an importance
to permit any consideration to delay their publication, to which
I wish to give the greatest authenticity.
[ have been long convinced by obsetvation, that many points
in the course of the moon have unquestionable influence on the
atmosphere, although the causes which modify these influences
are not sufficiently appreciated to enable us to predict what
events may be expected at those periods,
I add, that the results of my observations, recently completed,
has strongly confirmed my opinionin this respect, and hasinforms=
ed me, that, independently of the influences of the syzigies, the
quadratures, and the two apsides the nodes of the moon have very
remarkable influence, but more powerful in some parucular
eases, as I have succeeded in ascertaining.
Of 311 nodes and contra-nodes marked in my collecton of
Observations, 177 have eminently distinguished their iufluence ;
134 have manifested no particular power. The difference is 43°
in favour of the influence of these lunar points. But I observe
that the contra-nodes have somewhat more power than the nades,
and that especially the power of those contra-nodes which occur
during the half-yearly period of the sun’s being north of the line,
deserve the most scriousattention, There areeven circumstances
wherein I find that the evil influence of the contra-nodes has
never failed to shew itself. I shall describe them, as well us the
details of my recorded observations, in the next Annuare
Météorologique.
But it is of consequence that I should explain to the public,
that the tempest of the 18th of February last is the resnlt of a
contra-node which took place the evening before, under circum-
stances which I promise to explain.
(To be continued.)
A
JOURNAL
Or
NATURAL PHILOSOPHY, CHEMISTRY
AND
ook THE ARTS.
JULY, 1807.
ARTICLE I.
Facts foward a History of Prussiates. By Mr. Basiocit *
‘Tue Bo idias blue of the chen is seldom pure, as Impurities of
Scheele had already observed. Frequently, beside the alu. Prussin blue.
mine which makes a part of it, we find silex, carbonate
and sulphate of lime, sulphate of potash, phosphate and
red_oxide of iron, sulphur, ammonia not divested of animal
oil, &c. Tostudy the nature of this combination therefore,
it is indispensable, to use only a prussiate free from alum,
and sufficiently edulcorated with acids and boiling water.—
It even appears, according to a remark of Berthollet, that Prussiate of*
the prussiate of potash can attach itself to the Prussian blue potash
$0 forcibly as to resist ablution to a certain degree. I do not essential to
not think with him howeyer, that the surcharge of this salt opeherane
should be considered as an element essential to it; for when
the blue has been well prepared, and such is to be met with
in the shops, it leaves no trace of saline matter in the resi-
duum after distillation.
Prussian blue prepared without alum has a coppery ap- Pure eae
pearance like the best indigo. It loses only forty-five per "%°
cent by combustion. Its residuum is red pais of iron
without any mixture of, foreign matter.
: Palas de Chime Vol. LX. p. 185. Noy. 1806.
“Vou. XVIL—Jury, 1807. 8 ' Action
90 HISTORY OF PRUSSIATES.
Action of Alkalis.
Treated with The blue passed through caustic potash leaves a residuum,
caustic potash, which is nothing but red oxide blended with alumine. Its
colour is that of kermes, if the blue were of good quality ;
on the contrary it is pale and earthy, if the blue were sur-
charged with alumine: so that we may form a pretty good
judgment of its nature by the colour of its residuum.
may be de- Acids acquire no colour from the residuum properly
prived of all its washed ; which shows, that Prussian blue may be deprived of
acid at once. 2 s é 3 : ag
all its acid at a single operation; but for this it must have
been very finely pulverized, which is attended with some dif-
ficulty. If a few drops of alkali be added to water coloured
by the blue recently precipitated, it will be deprived of its
colour completely ; and in this case the oxide separated from
it will not afford the least trace of colour, when it is wetted
This seldom with an acid. In the process followed it frequently happens
ae that the ochry residuum retains either some remains of blue,
that have not been touched by the alkali, or a mixture of
prussiate of potash and ferruginous alkaline carbonate, or
all three of these blended together. I shall proceed to ex-
amine two of these cases, and it will be easy to forma judg-
ment of the third.
Blue left in the If for example an acid be applied to a well washed resi-
residuum. = duum, which still retains Prussian blue, this blue will not
discover itself in pulverulent particles, but in proportion as
the acid frees it from yellow oxide. There is no parti-
cular chemical union between this oxide and Prussian blue,
as hitherto has been supposed; at least we have no positive
indication, that the metallic salt, called prussiate of iron, is
susceptible, like so many others, of a maximum and mini-
mum state either of acid or of oxide; and if the mixture of
yellow and blue, which these residuums sometimes offer us,
be not green, as might be expected, it is because the yellow
oxide always covers these remains of blue in very great ex-
cess; atleast I have never found the blue tobe above oneor
two hundredth parts.
Prussiate of IT proceed to the second case. A residuum may contain
Reeinon a no remains of blue, if it were well pulverized, but it 2asily
kaline carbo- Fetains the two salts I have mentioned above. If an acid
nate, be then applied to it, each of them affords abundance of
5 blue
HISTORY OF PRUSSIATES; ; 9]
blue. We shall examine the particular mixture of these two
salts farther on: but if the residuum have been washed with
care, acids will not give rise to more blue. This washing not easily re-
is very tedious, it is true; for I have been obliged to pour ee
boiling water at'least twenty times following on a single
drachm of residuum, before I could obtain it completely
free; but when this is at length accomplished, acids will
dissolve it, without any blue being produced.
When these residuums effervesce with acids, they contain Effervescence
; : ; . , indicates a cars
carbonate of potash or of lime. The former may be carried ponate.
off by ablution; and the second will be detected by vinegar
after the washing. It is not the red oxide therefore, that Red oxide of
occasions this effervescence: it cannot indeed combine with (7 eee
the carbonic acid, consequently cannot take it from the bonic acid. .
potash, in exchange for the prussic acid, which it cedes to it.
’ In nature, as in art, it is only the oxide of iron at a mini.
mum, that can combine with the carbonic acid.
A pound of Prussian blue of the shops of fine quality, Prussian biue
has afforded as much as nine ounces and half of crystallized ee ae
prussiate of potash. It is by no means uncommon, to find Piast
in the mother water left to itself truncated octaedra an inch
in diameter. If the blue be contaminated with sulphuric
acid, at least four crystallizations will be requisite, to free
the prussiate entirely from sulphate of potash. The mother Lixivia not
water contains alumine, sometimes in abundance, sulphate?"
and phosphate of potash, ferruginous alkaline carbonate,
&c. Hence may be inferred the importance of employing the crystals
crystallized prussiate of potash in analyses, and not simple nee ae
lixivia of Prussian blue, as was formerly done. Prussiate as a test.
of potash is unalterable in the air, whether dry or damp; Chacters of
oats : : 3 thé prussiate,
boiling it for any length of time does not alter its nature:
its taste is swectish, and slightly saline, leaving after it a
faint impression of bitterness. It is insoluble in alcohol;
which separates it from its aqueous solution in a white snow
with the lustre of mother-of-pearl; and this lustre it retains
when dry, so that it might be mistaken for the argentine
gauze of acetate of mercury. Redissolved in water it re-
produces a common solution of triple prussiate,
This salty which I shall term a triple salt, or trisule, in- which isa tri
dliscriminately, to distinguish it from the simple prussiate of Pl¢ 4!"
H2 potash,
92. HISTORY OF PRUSSIATES.
potash, is as constant in its qualities as the most perfect
neutral salts. It is of a fine lemon colour, which it never
Containing Joses without changing its state. For this, as well as for
oe oxide ofits other two characteristic properties, that of crystallizing,
and of changing the red oxide of iron blue, itis indebted
to a portion of black oxide, which is essential to its consti-
tution. Without this oxide, confined like the other two
elements of the triple prussiate to an invariable proportion,
this prussiate in fact could neither crystallize, nor form blue
with solutions of iron, the base of which is at a maximum
This gives the Of oxidation. In short, it is from this very union, that the
prussic acid ~— nyinciple which saturates the potash of the triple salt de-
more decidedly ~, e :
acid properties, Fives those properties, as Berthollet remarks, that singularly
increase the analogies it bears to acids.
{in this point of view we may add, that the triple prussi-
ate occupies a mean betwixt alkaline and metallic salts.—
Hoewvever, when we reflect on one property of this salt,
which will be mentioned below, it is difficult to say, whe-
ther it be to the prussic acid simply, or to the combination
‘of this acid and potash, that the oxide of iron attaches it-
‘This combina- self, when it converts the prussiate into a triple salt. Thus
rene ape much is certain, that we do not yet by any means know
oxide and prus- '
sic acid not ob- What appearance or properties a prussic acid might have,
been by that should be combined with the precise dose of black ox.
ide, by means of which it can furnish a triple prussiate.
By treating ‘this oxide with prussic acid we can form Prus-
sian blue, but not that kind of ferrnginous acid, which is
capable of converting potash into @ triple salt. Of this we
must not lose sight; for it is well known, that Prussian blue
is not of a nature to combine with potash without leaving a
residuum. In short, the triple prussiate divested of its al-
Kaline base, if I may so say, is a compound, which no fact,
no appearance authorizes us to consider rather as a salt, the
acid of which has been particularly exalted by its union with
the oxide, than as a combination perfected altogether by this
“oxide.
Apparently 2 One property, which appears in fact ‘to militate against
oad our admitting the prussiate as a salt, the acid of which is
etween the
acid, oxide, exclusively united to the black oxide, is that of its resisting
andatkili. — ¥he action of alkaline hidrosulphurets. If these reagents,
which
HISTORY OF PRUSSIATIS. 93
which spare no other known metallic salt, have no action
on the triple prussiate, we are.to a certain degree justified
in presuming, that the oxide of iron is not exclusively at-
tached to the acid of the triple prussiate; unless indeed we
suppose, that the affinity of this acid for the oxide be so
great, as to defend it from the common fate of all other ox-
ides. We shall see however farther on, that an affinity so
extraordinary, unexampled as it has hitherto been in che-
mistry, is not impossible. I proceed to the trial of the hi.
drosulphuret of potash on the triple prussiate.
Hidrosulphuret and Triple Prussiate.
‘The hidrosulphuret of potash or of ammonia, even as- The triple
sisted by heat, has no action on this salt. If it contained Prussiate not
oe : : ecomposed by
any remains of ferruginous carbonate, it would be freed hidrosulphu-
from them, for the hidrosulphuret decomposes this carbon. ts.
ate. It may be filtered, if necessary, and the prussiate
will nevertheless crystallize in its usual form. Such a result
leads us to acknowledge, as has been hinted above, a very
peculiar intimate combination between the three elements of
the triple prussiate. But we shall presently see these very
hidrosulphurets contribute to our obtaining the white prus-
siate in all its purity, or that combination in which the iron
is at aminimum state of oxidation, which I made known in
my former memoir on Prussian blue,
White Prussiate.
Over a lamp place amatrass containing fifteen or eighteen White prussi-
grains of prussiate of potash, and two or three ounces of **© of kom.
hidrosulphuretted water. A few seconds after the ebullt-
tion and vapour have expelled the air, that occupied the up-
per part of the matrass, drop in slowly a very dilute solu-
tion of green sulphate of iron froma phial, into which a
few grains of sulphuret of the same metal have previously
been put, in order to keep its base at a minimum of oxida.
tion. Immediately a precipitate will be formed, rendering
the liquor as white as milk, and so it will remain as long as
the heat is keptup. This is the precipitate which I call
. white prussiate, and is the same as has been obtained by
Fourcroy, Vauquelin, Davy, and no doubt all, who, pay-
: Ing
94
Rendered blue
by oxigen from
the atnos-
phere.
Another me-
thod of obtain-
ing white prus-
Siate,
A third,
A. fourth,
White prus-
HISTORY OF PRUSSIATES. .
ing attention to the conditions necessary to ensure success,
have found, that the base of the green sulphate might be.
come that of a prussiate different from the prussiate which
has for its base oxide at a maximum. But as the black ox-
ide, in passing from one combination to another, never loses
its disposition to acquire a surplus of oxigen, we perceive,
as soon as the matrass is removed from the fire, that the at.
mosphere reacts on the milky mixture, and rapidly produces
tints of colour, which gradually diffuse over the whole a
fine deep blue.
This product may be obtained in another way. Let fall
prussiate of potash grain by grain into a very dilute boiling
solution of green sulphate, and a precipitate will make its
appearance, the whiteness of which will resist the action of
the air somewhat longer.
I shall add a few other processes, which, if they do not
increase conviction, may be. interesting from the variety of
the means employed.
Fill two glasses, one with nitrate of iron, and the other
with green sulphate, each in a state of very dilute solution ;
and drop into each a crystal of prussiate of potash. In the
former we shall see the crystal instantly coloured of so deep
a blue, that it resembles black velvet. In the latter it cracks,
separates, and falls into a white powder: but, as it had im-
bibed atmospheric air previous to the experiment, the pre-
cipitate is variegated like sage cheese.
Let two glasses be filled with boiling water; add to each
a few drops of prussiate of potash, and to one of them a
few drops of hidrosulphuret of potash, or of. ammonia,
likewise. Let fall into each a few drops of nitrate of iron;
and the former, as might be expected, will give a complete
blue; but the latter will exhibit the amusing appearance of
a precipitate, which, at first blue, will rapidly lose its co-
Jour, and become white, The theory of these facts is so
obvious, that I shal] pass it over: neither shall I here repeat -
all the other experiments given in my first paper to establish
the existence of two prussiates of iron. If the prussiate at
a minimum have no colour when it‘is not acted upon by the
atmosphere, we see, that the dried green sulphate is equally
colourless. The absence of colour in one of these salts is
f surely
HISTORY OF PRUSSIATES- 95
surely not more surprising than in the other; and, if we a SM ie
- obtain red oxide by applying alkalis to a blue prussiate, on precipitated: B
the contrary we obtain black oxide from a white prussiate.
But these differences, which might be inferred from theory,
agree perfectly with those exhibited by the red and green
sulphates under similar circumstances.
In my first paper I directed to pour the prussiate of pot- Caution.
ash on the sulphate ina phial, to avoid as much as possible
the admixture of air; but this succeeded imperfectly; first
because cold liquors always have air in them, and secondly
because I had not thought of sulphuretted hidrogen to free
them from it, I did not then know how it acted with re-
spect to these salts. ;
If for instance a solution of green sulphate be diluted Excess of acids
with three or four times its bulk of sulphuric or muriatic 4° Pot change
the white prus+
acid,’ the excess of these acids makes no alteration in the siate to the blue
result. _Asthe white prussiate wants colour only from de- * eect devas
fect of oxigen, it may be supposed such an addition is not mene oxi
calculated to impart it. These concentrated acids may alter 5°
the whiteness of the prussiate indeed, but they can never :
bring it to a complete blue.
Muriatic acid boiled on white prussiate is equally inef-
fectual.
Not that this boiling acid is without action on the white Action of mu-
prussiate; for I have observed, that there is some white Sipioe 154
prussiate destroyed, prussic gas evolved, and black oxide»
feund in solution. The little Prussian blue, that is formed
by the introduction of air, during the interval of these
mixtures, predominates over the white, and changes its co-. -
jour to a greenish.
The blue prussiate boiled with the same acid likewise gives and on the blue
out prussic gas, and parts with red oxide, but less of it is P'UssiMe:
destroyed than of the white prussiate. From these facts we
may infer, that the muriatic acid, assisted by heat, is capa-
ble, in strictness, of Aesbaniokine prussiates, and assuming
its rights of a stronger acid over the prussic; which would
not be at all surprising, but at least I believe it would re-
quire considerable time,
Prussiate
86 HISTORY OF PRUSSIATES.
Prussiate ef Potash and Acids.
The crystal- Let weak sulphuric acid or muriatic be heated in a mate
eased, four ae rass with crystals of prussiate of potash. When ebullition
acids, commences, gas escapes, and may be received under a jar
over mercury, or burned by applying to it a lighted candle.
The flame will be variegated with red, violet, and. yellow ;
and during the extrication of the gas the liquor will be thick~
ened by the production of a white precipitate, which changes
to a blueish. When all the gas is evolved, throw the mix-
ture into boiling water, brighten it with oxigenized muriatic
it affords 34 or acid, wash, and dry the product in a capsule. Four ex-
aig he ae ' periments, iad at different times, afforded me thirty-four
or thirty-five parts of complete blue from a hundred of the
triple prussiate.
' I proceed to the consequences :
Prussian blue A hundred parts of Prussian blue, without alum, yield
contains 54 or fifty five of red oxide by combustion. The same blue, de-
“55 of red oxide
of iron. stroyed by nitric acid, gives fifty-four. It cannot be ques-
tioned therefore, that Prussian blue contains fifty-four or
The pfussiate fifty-five hundredths of red oxide. From these data thirty-
eaeichaget five parts of blue ought to produce about seventeen of black
19 per cent to oxide, or nineteen of red. Hence it follows, that, when
ica le iron was formerly separated from a solution by prussiate of
“ah tof potash, this salt added to the product the nineteen hun-
dredths of red oxide arising from its own decomposition ;
but the addition was still greater, when a simple alkaline
lixivium of Prussian blue was used mstead of the crystal-
lized prussiate. The reason of this we shall see presently.
Prussian blue »- When Prussian blue is treated with a common lixivium of
sala potash, part of the alkaline carbonate loads itself with
ash. : red oxide ; and the result is a solution answering to Stahl’s
martial tincture, of which pure potash is insusceptible.—
This solution, which may be prepared likewise by adding a
few drops of nitrate of iron to a solution of carbonate of
potash, will not occasion the least change in prussiate of
potash, even by standing together. It is the same ferrugi-
nous carbonate, which, as I have said, is found in the
mother-water. In effect, if an acid: be added to the mixture
of these salts, a perfect blue is precipitated, because the
new
HISTORY OF PRUSSIATES. O97
new solution of oxide, which takes the place of the ferru-
ginous carbonate, decomposes the prussiate of potash, as
any solution of iron would do.*
When Prussian lixivium therefore is ongndyea instead of Inaccuracy of
a crystalliaed prussiate in an analysis, we add to the pro- Mande fat
duct in, the first place red oxide, which made part of the tes.
ferruginous carbonate; and in the next black oxide, which
is a constant element of the triple La pee contained in the
lixivium,
Chemists very soon discovered the fants of these lixivi-
ums, though they were not at first aware, that they con-
tained two very different combinations of iron, the carbon.
ate of which l am speaking, and the triple prussiate. Many, Attempts to
on secing thy blue they yielded with acids, even thought this COS a
blue existed1n them as a distinet substance ; and endeavoured
to HE ai it, whether it were Pins blue or oxide,
not affecting the alkaline prussiate, which they sup-
posed to possess the tinging property without being in-
debted for itto iron. From their attempts arose the receipts
for precipitated lixiviums, which occur in every work on
chemistry. But since the inquiries of Scheele and Berthol-
let, it has been found, that these receipts answer the end
but imperfectly ; for it is easy to see, that it was not suffi.
cient to free a lixivium from the oxide introduced into it by
the carbonate; there remained farther to be guarded against
the black oxide, which belongs to the triple prussiate, and
the existence of which was the less suspected, because the
addition of acids, without the intervention of light or heat,
could not render the products of its decomposition percep-
tible.
Ishall not stop to analyse the phenomena, that presented
themselves during the preparation of lixivia either hot or
cold, because, as the inutility of prussiates for the evalu-
ation of iron in analyses is now well known, the particu.
Jars would not be very interesting. In the same manner I Other prussi-
shall pass over the proposed test liquors with ammonia, lime, ed iS sala
magnesia, &c. because they arc themselves triple prussiates, counterproof.
* Ttis the mixture of these same salts, which enables the mother- Prussian blue
waters of soda to afford Prussian blue by the addition of an acid. from mother
n Water of soda,
98 ‘ HISTORY OF PRUSSIAETS,
on which consequently we cannot rely, unless we join with
No prussiate them the countezproof proposed by Berthollet. I shalt
Pee ties: only add, because this should remain consigned to the his-
unless black — tory of the science, that, when a chemist still employs with
rong io effect a lixivium, or test liquor, purified by an acid, we may
be certain, he has not obtained a complete and entire sepa.
ration of the iron, as he flatters himself: for it is certain,
that every lixivium capable of affording blue with a solution
of red oxide contains black oxide, since without the assist
ance of this exide there would be no tingeing prussiate; in
other words, every prussiate of potash, not rendered.a tri-
ple salt by black oxide, is incapable of forming blue with a
solution of iron, the oxide of which is at a maximum, as
is most commonly thé case with those produced in analyses.
Prussiates of no This is a fact which Scheele perfectly developed. Wemay .
fartl than
rey :. oe hie conclude therefor e, that the alkaline or earthy triple prus-
presence of siates_ can no longer be considered as useful in analysis, any
= farther than litmus, galls, and other reagents, which merely
indicate the presence of a certain principle, without being
capable of ascertaining its quantity.
Action of sul- The aqueous sulphuric acid, applied to the triple prussi,
phusicacid, ate, affords the same results as the muriatic. A hundred
parts of prussiate produce a hundred and fifteen or a hun-
dred and sixteen of sulphate of potash. If we knew ex-
actly how much alkali the sulphate contained, we might.
thence deduce the quantity of the base of the prussiate. A
hundred parts of crystals of prussiate lose ten of water by
distillation.
ae neces- —_'T'o complete itsdecomposition by the acids, itmust be kept
’
entircly, and obtain the entire separation of the white
prussiate, which is formed during the operation.
ortheassistance The prussiate of potash dissolves cold in the muriatic
of light. : ‘
acid, without being decomposed. This mixture, as Ber.
thollet found, requires the assistance either of light, or of
heat.
Vinegar, assisted by boiling, ie i it also: prussic
gas escapes, and white prussiate is formed, which does
not change blue so quickly as with the preceding acids
finally, this prussiate, which does not appear till the mo,
’ ment
Action of vine-
gir.
boiling at least half an hour, in order to dissipate the gas _
HISTORY OF PRUSSIATES. 99
ment when the ternary combination begins to dissolve, com-
firms by its whiteness the fact, that it is only the oxide at a The black
Les - ike em : oxide of iron
minimum, iia has the premleserot ee into the for- onto
mation of the triple prussiate. ‘his is one of those truths, triple prussiate.
on which Scheele left nothing to be desired; yet the dis-
tinction of the oxides in this substance is a point, to which
subsequent chemists have not paid all the attention it
deserves.
Black Oxide; an Element of Prussian Blue.
We have just shown, that this oxide, in a constant pro- tt is one es-
portion, is essential to the constitution ‘of the triple prus- Pi eh
siate; but there is another object, that has also some claim pjue.
to attention, which is, that this oxide is capable of follow-
ing the prussic acid from one combination to another, with-
out changing its state; that it can pass from prussiate to
prussiate and back again, and even circulate through the
most oxiding medivms, without losing the state of a mini.
mum oxide: and this I conceive to be a point of view,
which has been overlooked in the history of prussiates.
If, for instance, we may say with truth, that the prus- hino Leaf
siate of potash would be neither yellow, nor crystallizable,
Mor tingeing; we may assert with equal foundation, that
neither would prussian blue be formed without the inter- °
vention of thisoxide: and in fact, when we make prussian
blue with a solution of red oxide and of triple prussiate
of potash, the black oxide in the latter salt enters into the
new combination jointly with its acid; whence it follows,
that this oxide, which is an element of the triple prussiate
of potash, becomes so afterward of prussian blue; and
even, as will be seen presently, of all the other metallic
prussiates, that are made with this salt.
This black oxide is so firmly intermixed in the compound Resists farther
of prussian blue, and so well defended from all farthery)°.
oxigenation by its union with the prussic acid, that we combined.
never fail to find it again in this blue such as it was in the
triple prussjate of potash. I will say more; if we make
the blue with this prussiate and the green sulphate of iron,
the oxide of the latter will be raised, as is well known, to
it maximum, in proportion as the blue becomes coloured
by
100
Neither the air,
nor boiling
nitric acid, nor
oxigenized
muriatic, oxide
it more,
except as these
acids destroy
the blue itself.
Red oxide of
iron will not
combine with
prussic acid,
but black will.
Affinity of the
prussic acid for
a given propor-
tion of black
oxide, very
strong.
Experiment 1.
HISTORY OF PRUSSIATES.
by the impression of the air; but it certainly will not. be
the same with the black oxide, which passes into the prus= -
sian blue jointly with the acid. This oxide will not. lose
the quality of being at a minimum, which it had in the
prussiate of potash; that is to say, if, during the exposure
to air, the basis of the green sulphate, and consequently
that of the white prussiate, raise its proportion of oxigen
from 28 to 48 per cent, the black oxide, the inseparable
companion of the prussic acid, will not participate in this
super-oxidation, but will invariably keep to its 28 per
cent.
Not only the atmosphere, which so easily raises the
bases of the sulphat, muriate, and white prussiate to their
maximum, loses all its activity when applied to the black
oxide in question; but neither boiling nitric acid, nor the
oxigenized muriatic, can increase its oxidation. These
acids are capable indeed of destroying prussian blue, and
even reducing it to red oxide; but as long as any blue re-
mains to be destroyed, this will to the last retain its black
oxide in al] its primitive integrity.
If red oxide be treated with prussic acid, no kind of
combination will take place between them. This is agree.
able to the observation of Scheele. But. if we employ
black oxide, we shall obtain a greenish prussiate, which
will be rendered perfectly blue by the action of the air.
Black oxide therefore enters into the composition of prus- -
sian blue. If this oxide were unnecessary, or if the red
oxide might serve exclusively as the base of prussian blue,
it does not appear why this oxide, brought into centact
with the prussic acid, and even its solution mixed with
simple prussiate af potash, should not afford prussian
blue.
I have remarked above, that the affinity of the prussic
acid for such a dose of black oxide, as adapts it to the
production of the triple prussiate, may be sufficiently
powerful, to protectit from the common fate of oxides
combined with acids in general: and in fact it appears to
me, that this inference may be drawn from the following
experiments,
Pour hidrosulphuret of potash into a phial on prussian,
hlue
HISTORY OF PRUSSIATES. , 10]
blue, and keep the mixture closely stopped: at the expira-
tion of a few days, the hidrosulphuret will be converted
into a triple sulphate, and the red oxide of the prussian
blue only changed into black hidrosulphuret. Whence it
appears, that, if the red oxide have followed the example of
all other oxides, when the hidrosulphuret finds them com-
bined with acids, it is not the same with the black oxide.
Hidrosulphuretted water brings back prussian blue to Experiment 2»
the state of white prussiate, as it does the red sulphate to
that of green sulphate. This is a fact which I,made known
in my first memoir, and the power of this reagent never
goes farther; but the hidrosulphuret of potash completely
changes the red and green sulphates into black hidrosul-
phuretted oxide. Why then cannot this hidrosulphuret
extend its action to the black oxide in question? Certainly
some singular affinity, of which I believe there are few in-
stances in chemistry, enables the prussic acid, the weakest
of all acids in so many respects, to protect this oxide
against all the power of the alkaline hidrosulphurets.
All the metallic solutions, that afford prussiates with the The same in
triple prussiate of potash, no doubt follow the example 1 io i sre
those of iron. The prussiates resulting from it will re-
tain inal] its integrity the black oxide, which the prussic
acid carries with it; but it is time to lay before the reader
the capital pore which demonstrates, that prussian
blue isa triple salt; and that the black oxide, which had
passed from the triple prussiaie of potash into the prussian
blue, is capable of passing back again from the prussian
blue to potash, without having for a moment quitted its
state of a minimum oxide. This experiment I have no
doubt is anticipated by every one, who has formed a clear
idea of the triple prussiate of potash.
- Let us take, for instance, a prussian blue, which has Proof that
-experienced all the action that the atmosphere, or the most og
oxiding acids, can exert upou it. Let us apply to it pure
potash, and we shall obtain a lixivium, which will yield
only a iriple prussiate, or that combination in which we
find the prussic acid constantly united with the usual dose
of black oxide. If this. prussiate be really such as I have
apnounced, and the-reader will have no difficulty to believe,
there
102 HISTORY OF PRUSSIATES.
there can be no objection I imagine to the theory that
asserts, that the white er blue prussiates are triple com.
binations, as well as the prussiate of potash, which has
concurred to form them.
Triple prussiate Pyussiate of manganese being put into a solution of pot-
hase A eee ash, the result was the crystallizable triple prussiate of
potash, of a yellow colour, and containing its due propor-
and of copper. tion of black oxide. This prussiate of manganese then is
a triple combination, containing the black oxide. The
prussiate of copper of a sanguineous colour is no doubt
another, for the simple prussiate of copper is yellow.
Scheele informs us, that other oxides also have the pro.
perty of converting the simple prussiate of potash into a
Perhaps other triple salt. This apparently opens a field to a series of re.
ee Pi6" ‘searches, which are the more interesting, as they may lead
to the discovery of some colour equally valuable with prus.
sian blue; and lastly we may conclude, from all that has
Simple prus- been said, that no simple prussiate of iron exists; a kind
siates of other os tains elie
featals: of combination however, of which other metals are sus-
ceptible, as will soon appear.
Distillation of Prussian Blue.
Desricies This prussiate is destroyed by exposure to a high tempe-
distillation of ature. The new products, that arise from it, confirm the |
uae tna theory Berthollet has given us respecting the nature of ‘the
prussicacid. We obiain an acid which escapes destruction,
carbonate of ammonia, a little free carbonic acid, gaseous
oxide in abundance. An ounce of good blue of the shops
afforded rather more than five pints of this gas, with as
much carbonic acid as made up the whole three quarts.
The water of the trough contained prussic acid fixed by
ammonia. This prussiate, as is well known, follows the
steps of that of simple potash; it cannot produce blue
with solutions of red oxide, but it does with those of
oxmics at a minimum, because at the same time it forms it-
sclf into a triple or tingeing prussiate.
The residuum weighed five drachms fifty-two grains.
It was perfectly black, and very attractable by the magnet.
A pyrophorus. It is a pyrophorus, which takes fire with rapidity. After it
has been kept in a phial not closely stopped, so long that it -
will
HISTORY OF PRUSSIATES. 103
will not kindle of itself, if it be wetted with nitric acid of
40°, it burns with great vividness. I am inclined to think,
that in this combustion the iron burns in conjunction with
the charcoal.
If the prussian blue were without alum, this residuum Residuum.
eontains nothing but charcoal and iron.
Muriatic acid disengages from it with the greatest facility Treated with
that aromatic hidrogen, which announces iron steelified, or ™"™™S au
combined with carbon. ‘The residuum is pure carbon, one
of the elements of the.acid destroyed. As to the carbonic
acid and gaseous oxide, it is equally evident, that they are
the two oxidations ef carbon, a maximum and minimum,
produced by the exigen of the two oxides found in the
prussian blue.
This decomposition is obtained by a heat so gentle, that Gaseous oxide
‘it appears to mea convenient mode of procuring the gaseous hae
oxide of carbon. As there is not the slightest appearance No appearance
‘of oil, it is somewhat surprising, that in the course’of the °! %-
destruction of a compound in which carbon and hidrogen
abound, no part of these combustibles should be found to
present themselves under circumstances in which oil would
be formed. Rech ,
The oily and aromatic character, that the hidrogen as. Iron unites with
sumes during the solution of the residuum, demonstrates ee past
likewise, that the combination of iron with carbon does
not require a very high temperature. The charcoal of
blood, which is obtained by a very low heat, equally con.
tains iron in the state of carburet; for this likewise yields
' sedoriferous hidrogen with muriatic acid. I think I have
somewherg else observed, that Priestley was struck with
the bituminous smell of the hidrogen furnished by car-
buretied iron. .
s
Distillation of the Triple Prussiate of Potash.
This salt loses ten per cent of water, and with it its Destructive
1 Signe ae Lc eeombieicah a t Boot distillation of
colour, for it becomes white; but it does not begin to the triple prus-
soften till it is ata red heat. Some chemists have imagined, siate of potash.
thatroasting or melting it would afford the means of freeing
it from oxide, but the following results will show, that
‘these processes lead to nothing useful.
When
104
Progress of its
decomposition
by heat.
The residuum |
“pearly snow is formed, which may be collected on a filter.
examined.
HISTORY OF PRUSSIATES.
When this salt enters into fusion, a little prussic acid
escapes, which is seized by the ammonia that is formed at
the same time. Afterward a nebulous vapour rises, which
condenses in the neck of the retort in a meally powder.
This vapour. is not reproduced when the fusion is at an
end. On examination the sublimate has the alkaline and
bitter taste of simple prussiate.
Alcohol dissolves a portion of it, and what separates
from it is triple prussiate unaltered: that is to say, this
gives prussian blue with solutions of red oxide, while the
other cannot.
If a lighted candle be applied to the mouth of the retort,
the prussic acid burns alone; and the carbonic acid, arising
from its combustion, forms with the ammonia crystals of
ammoniacal carbonate, which. condense. in the neck of the
retort a few lines beneath the flame. We will now pro-
ceed to examine the melted prussiate.
The mass resembles melted muriate of soda, is of am
ashen gray, and strongly attracts moisture.
If we taste a bit of it, we find nothing of the sweetness
of the triple prussiate, but an alkaline taste, flavoured
with the bitterness of the kernels of stone fruit. This
flavour announces, that there is simple prussiate of potash
in this residuum. A few drops of acid extricate a gas,
which does not belong to this prussiate, and which give a
suspicion, that it contains carbonate of potash also.
. Finally this mass, if set by to dissolye, deposits a black,
micaceous, shining powder. On collecting it ina filter, it
4s found to be a mixture of charcoal, pure iron, and a
jittle sulphuret of iron. The last is an accidental product.
Ats sulphur proceeds from the decomposition of the sulphate
of potash, from which it is not easy to free the triple
prussiate. This powder is obedient to the magnet. A
weak acid disengages first’ sulphuretted hidrogen, then
aromatic hidrogen, and at length nothing remains but
Aharcoal powder.
Examination of the Solution of the Restduum.
If alcohol at 25° be mixed with it, immediately @ shining
Dissolved,
HISTORY OF PRUSSIATES: 105
Dissolved and crystallized, it affords yellowish crystals, of
a sweetish taste, and furnishing prussic acid and white
prussiate, when acted upon by muriatic acid. This is the
prussiate freed from oxide proposed by Mr. Richter.
The alcoholic solution being distilled almost to dryness,
and the residuum covered with alcohol at 30°, one portion
is dissolved, and another falls to the bottom.’ The preci-
pitate is found, on examination, to be carbonate of potash, ~
with a remnant of the triple prussiate. The new solution
being distilled affords simple prussiate, which is discover-
able by its taste, and by its property of not producing blue
_ with solutions of red oxide. These are the products I have
found after subjecting the triple prussiate of potash to
fusion. .
Consequences.
The triple prussiate cannot support a considerable tem- Recapitulation
perature without being simplified in its composition. It of Ge SeaNE tS
frees itself from black oxide, and passes to the state of
simple prussiate: but this too is reducible to something
more simple, as we shall see below; and it then leaves in
its stead potash and the usual results of the prussic acid,
ammonia, and carbon. <A portion of the latter serves to
disoxigenize the black oxide, reducing it to iron, and form-
ing carbonic acid with its oxigen.
During these changes, a part of the triple and simple
prussiates escape being acted upon, in proportion no doubt
as they become enveloped in the carbonate: but it is to be
presumed, that a high and continued heat, in vessels capa-
ble of supporting it, would ultimately reduce these prus-
Siates to two binary combinations, which are ammonia and
carbonic acid, potash, iron, and some remains of carbon,
that the oxigen of the iron and the water were incapable of
acidifying.
Simple prussiate of Potash.
This is obtained by saturating potash, in Scheele’s mode, Mcde of ob.
“with prussic acid disengaged from the prussiate of potash ate ee
or of mercury. But amore expeditious way is keeping of potash.
alcohol on a concentrated lixivium of animal coal, shaking
Vou. XVII.—Jury, 1807, . I it
106) HISTORY OF PRUSSIATES- .
it from time to time; and the progress of. the solution will ,
be discovered by the alkaline and bitter taste of the alcohol...
The lixiviums of .charcoal of blood or of. leather, are .
seldom exempt from a little hidrosulphyret, because the ..
a sulphate that contaminates potash introduces sulphur into
Animal cha them. . In this case it enters into the alcoholic solution ;
ha ag but the charcoal contributes to it likewise, for I have pre-
pared Jixivia with charcoal of blood and very pure carbonate
of potash, and yet found hidrosulphuret in them, though
in smaller quantity... It must not be forgotten indeed,
that. sulphur is found among the products of blood. It
even appears, that, like phosphorus, it is capable of
fixing in the charcoal, but not combined with the iron it
contains; for the aromatic hidrogen, mentioned above,
does not afford the. least indication of sulphur by its
smell.
Characters of The simple prussiate is easily recagnined by its bitter .
i lg alkaline taste, and the aromatic flavour with which it
ei. strongly perfumes the mouth. It precipitates solution of
copper yellow, and does not afford blue with a solution of
the red oxide of iron, but precipitates it of an ochry
yellow, asa pure alkali would*. Finally, it affords. blue. ,
with a solution of common sulphate of iron, because it. .
first constitutes itself a triple prussiate, and afterward pro.
Blackness from duces white or blue prussiate of iron. If the prussiate be
a black, it is because the alkaline hidrosulphuret introduces
acid. into it hidrosulphuretted oxide; ‘but it may be freed from
this by a few drops of acid, andthe prussiate of iron wilt
Must be closely appear alone. The simple prussiate does not keep well .
stopped. unless closely stopped. Scheele has shown, that. the car.
bonic acid is sufficient to separate the prussie from the
* In a memoir on the stone of Sigena, I had mentioned this’ ©
combination as possible, but it was from mistake. A’ sulphate of
iron, which I had superoxided by nitric acid, retained notwith-
standing a portion of black oxide, and this deceived me; and°-
Scheele,. whom I contradicted on this point, saw more clearly
than I,
In our abridginent of this memoir, Journ. Vol. XII. p. 2. we
aid not insert the remark here alluded to, as we were persuaded
that Scheele was right, and that our author must have pac de-
ceived by some circumstance or’other, T. fy
. bal Apia
HISTORY OF ‘PRUSSYATES.. - 407
potash, their affinity being so weak. When itis et Com:
bined with black oxide, it-will nét~erystallize by concen. ©
tration, but fixes in a mass, in ~whieh- however: ‘sume saline
lamine are distinguishable.
This prussiate is the test liquor ae byS Scheeie. Tts Of little wse as
utility in analysis i is very confined’: since all solutions, “in-* t¢#*' ;
which the iron is ata maximum of oxidation, and this is- ‘the 4
most common case, are not in the least affected by this re-
agent, as he himself observed. To employ it with: utility,
part of the oxide of the solution must be brought back to’
a minimum, which is not easy, or to be done without 4
risk of increasing the difficulties of the aaa
Its Diciaibooitivns
The aqueous solution of this prussiate gives out part of Decomposed
its acid at a boiling heat, which sufficiently demonstrates, 5 ad
that this combination is neither solid, nor comparable to
any of those formed by oxigenized acids. It froths con.
tinually, and has something saponaceous. A lighted ©
candle, applied to the orifice of the retort, sets that por.
tion of acid on fire: but its loss is not ddiasifed to this, for ©
that portion, which the salt retains more strongly by means
of the potash that begins to predominate, likewise expe-
riences a slow but regular destruction from the effect of the |
heat, which converts it into ammonia and carbonic acid.
Examine the product at whatever period of the boiling you =
please, there will always be found in it carbonate of am-
monia mixed with a little prussic acid; and at length, when |
the water begins to fail, this eaemsiaels condenses 1 in needles
in the neck of the retort. z
If water be supplied, that the boiling may continue, the’
_ same products will be found in the water of the receiver $
but after four or five successive distillations. in thé.same_,
“Manner, they cease to be perceptible, though the saline -
residuum still evidently contains prussic acid.) 04 @ ginbuste
‘On treating this residuum with alcohol, part is ‘dissolved, The residuum.
which is found to be. prussiate of potash; but the saline
‘Matter left undissolved is carbonate of potash. The two
following experiments leave no doubt of the destruction of
the ; simple prussiate by a boiling heat... hie Anita ord bas
I 2 : Prussiate
108 HISTORY OF PRUSSIATES.
Boiling con- Prussiate of potash does not render turbid. a solution of
ia rear. MUriate of lime; but after it has undergone ebullition for
bonate. some time, it precipitates it copiously in. the state of car-
bonate. The prussiate of potash therefore must nATE been
converted into carbonate of potash.
Experiment. Two measures of solution of prussiate, one in an na-
tural state, the other altered by long boiling, were em ploy-
ed to precipitate common sulphate of iron. Each afforded
blue; but after the brightening, that produced by the
former was three times as much as the other.
Decomposed If dry simple prussiate be heated to redness, carbonate
by Beat. of ammonia will pass over, contaminated by an oily vapour
similar to that of hartshorn. The saline mass being dis-
solved leaves behind charcoal, and is carbonate of potash
mixed with a portion of prussiate not decomposed.
Consequences.
The simple All these results unquestionably authorise us to poriclade,
Lid tee Se that the simple prussiate of potash is a feeble combination,
tion, as Scheele had already found, the principles of which are
easily dislodged, like all that are complex. We see in fact,
that part of the acid separates from the potash by the
effect of dilatation simply; while another part, subjected
longer to the agency of caloric, is destroyed by being
changed into ammonia and carbonic acid, Let us proceed
i to. the application.
Butnot the That the triple prussiate of potash is not deranged by
triple prussiate: repeated ebullition is a fact. The lixiviums employed in
manufacturing prussian blue contain, as we shall see below,
-both the triple prussiate and the simple prussiate. There
-is not found in them, however, any ammoniacal salt. alt
might be presumed, indeed, that the great excess of care
bonate of potash they contain would be incompatible with
», such a salt; yet they evolve ammonia, as long as they con-
_ tinue in ebullition. ,Whence then can this ammonia ‘pro-
ceed, if not from the decomposition of the simple prus-
Boiling the —siate? We may infer, therefore, that boiling the lixivia,
lixivia in ma-
nufactories of OF concentrating them by evaporation, is liable to injure
prussian bine them by the destruction of that very prussiate, which can-
manouss _-.not.be too sedulously preserved; and as the carbonate of
eae i potash
HISTORY OF PRUSSIATES. ~ - 109
potash is likewise one of the principles resulting from this
destruction, ‘it does not cease to add to what is found there
already. ~
- Curaudeau was aware of the injury occasioned by boiling unless a little
the lixiviums, and happily prevented its effects, by adding Wee at ne
_ to them a little sulphate of iron, agreeably to the principle
of Scheele, who made known, that the simple prussiate
was converted into a triple prussiate, whenever it could to form the
acquire a portion of black oxide, and thus defended itself Sil ee
from decomposition. As to the products of the destruc.
tion of the prussiate by fusion, or by ebullition, undoubt-
edly there is nothing extraordinary in them, since it is suf-
ficient for us to be acquainted with the nature of the prus-
sic acid to foresee them; but it is not the same with respect
to the carbonic acid, which presents itself during one of
these destructions. Whence, for instance, comes the Whence the
oxigen, which, during the ebullition of the aqueous prus- as acid
siate, acidifies the carbon of the prussic acid? Either this
oxigen must be one of the principles of the prussic acid
that is destroyed, or we must suppose, that a decomposi.
tion of water has taken place. I do not think we are yet
sufficiently advanced, to choose between these two opinions ;
put till we have a clearer insight into the subject, I cannot
help saying, that, if we reflect on the circumstances ac-
_companying the production of the’ prussic acid, we shall
be more inclined to adopt the opinion of Berthollet, than
any other hypothesis. His words are: ‘* it appears. to yyoc¢t probabig
'me difficult to conceive the existence of oxigen in a $ub- nooxigen-in —
Stance, which contains elements so strongly disposed’ to “a: bh
, “form particular combinations with it, as hidrogen and car-
bon, and yetis capable of enduring a pretty high tempera-
_ture without being decomposed.” In fact, to admit that
“this acid is an oxigenized compound, we must suppose,
_ that such an acid is capable of disputing oxigen with the
~~ carbon by which it is surrounded on all sides; and not only
: place it at the head of the acids, but even of those oxides
si. _which are known to be most difficult of reduction.
(To. be-continued. )
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112. ~ EAST INDIA PLANTS.
The Specimens noted in the following Letters are e placed in
» °°" “the Society’s Repository. :
DEAR SIR,
Fjoo, the fibres I think it more that probable that the Society of Arts,
of the leaves of & 6, do’ not -possess any specimen of the vegetable fibres,
commonly called Ejoo in the Kast Indies. I have, therefore,
the pleasure of sending you a parcel of that substance, con-
sisting of six small rolls, the produce of a small tree for
one year. The tree produces, on an average, six leaves
every year,.and each leaf yields-from about four to twenty
ounces. ~ [tis No, 4. of my first paper on the comparative
strength of various vegetable ‘fibres, published in the xxii.
vol. of the Society’s Transactions. A description of the
tree has lately been” published by Labillardiere, under the
the Arcnga name of dArenga Saccharifera...\tis the Anou of Marsden
Saccharifera. jn his History of Sumatra, page 77: in Rumphius’s Her-
barium Amboynense, vol. i. page 57, and table 13, a very
full account of this valuable palm will be found. By Louri-
ero, in bis Flora Cochinchinensis, p. 759, itis called Bo-
rasus Gomutus. The cultivation of this beautiful, stately;
Mide ines and very uséful palm may, I think, with the prospect ef
ropes. great advantage, be encouraged in the West Indies. . For,
besides the above-mentioned fibres, which are in high esti-
mation for thick cordage and cables in India, this palm
Affords much © farnishes.' sugar, and abounds, as before mentioned, ‘pro-
wine and sugar. hably, more than any other, in wine, which, in. its recent:
state, is a pleasant and wholesome beverage, and is also cone,
verted by the Malays into ardent spirits; and. when the.tree.
arrives at maturity, the pith of it is one of the varieties) of.
sago meal used by these people in their diet. ;
Asubstitute for - 1 have the pleasure also of sending. you a spécimen a a
cork, most curious, .light,, vegetable, substance, the spreading)
stems of Acshynomene Aspera, a water plant, called by the,
Hindoos and Bengalese’ Solah, and Fool-Solah.\ It-is.em-
ployed by them for a variety of. purposes, such as floats for
fishing nets, artificial flowers, &c. Might it not be advah-
tagzeously employed instead of cork, in making “jackets to
swim with, and in life-boats, &c.? “ At all evehts, the!
bare circhmstance of making known the existence of such a,
plant,
ON COFFEE. 18 ,
_ plant, and the.place in which it flourishes, wili, I am per.
suaded, be acceptable information to the Society.
Iam, Dear Sir,
Your most obedient humble Servant,
W. ROXBURGH, © 5S
Ill.
Extract froma Dissertation on Coffee, its History, Pro-
perties, and the Mode of obtaining from it the most plea-
sant, wholesome, and economical Beverage: by ANTONY
Axexis Caper pe Vaux, - Member of various Academies:
with its Andlysts, by Cuartes Lewis Caper, Apothecary -
“in ordinary to his Majesty the hepa salen of
Chemistry, §c.*
Passinc over the historical part, which. is sufficiently
known, we shall confine ourselves to the chemical and eco-
nomical.
Raw Coffce treated with Water.
When boiling water is poured on coffee as we find it in Decoction f |
the shops, it acquires a yellowish green colour.+ If the ™v coffee
treated with, re
action of heat be continued, the decoction grows brown, agents,
and a light scum rises, which remains insoluble. The de»
eoction passes clear through the filter, but becomes turbid
on cooling. A little caustic potash poured into this decoc-
tion gives it a deeper brown, and ammonia produces a simi-
Jar effect.. Lime water forms in it 2 copious flocculent pre- .
cipitate. Sulphate of iron converts it into a black ink.
“Solution of onan is not rendered turbid by it. Oxigen-
Pkiurnal de Physique, Vol. LXIII. p. 216, Sept. 1806,
t+ When coffee is fresh gathered, its decoction is of a fine emerald Lake from
green. A lake might be made of it, and Mr. Dupont de Nemours coffee.
“informs me, that in the West Indies it is used for washing and co-
touring maps.
ized.
] l4 ON COFFEE.
eukte ized muriatic acid deprives the decoction of its colour but in
part; and, if-awalkali be added to this mixture, it becomes
red. TS ON Te id
Distillation.
Distilled “yield- IT distilled eight ‘pounds of water with a pound of raw
eda volatile oll. coffee, and obtained an aromatic water, on the surface of
. which were a few drops of a concrete oil, similar to that of
the-mgrica cerifera, or candleberry myrtle. The decoction
remaining in the still was viscous. This I diluted with a
The decoction little water, and poured into it alcohol. A copious preci-
gummy. pitate was thrown down, which, collected on a filter, was
soluble in water, and had all the characters of mucilage.
Resin leftin The coffee from which the water had been distilled, being
thecoffee. dried in a stove, and digested in alcohol, afforded a tincture,
which gave a precipitate on adding water.
The decoction ° The aqueous decoction of raw coffee does not redden ve-
nelly litmus getable blues. ‘With litmus it even produces a green. . All
3 the chemists who had analysed coffee before me have said,
that the decoction held in suspension a free acid, which red-
‘dened blue vegetable colours. Geoffroy even went so far as
-to assert, that water distilled from coffee by the heat of a
and contzinead W2ter bath was rendered very sour. I have tried five°differ.
no acid. ent sorts of coffee, and repeated the experiment more than
twenty times, but the decoction never appeared sour to me.
Decomposed It decomposes sulphate of alumine, and precipitates its
alum. earth, which it colours slightly.
- Raw Coffee treated with Alcohol.
Aleohol ex- “Alcohol! becomes slightly tinged by standing on dry coffee,
tracts its resin, even without ‘heat, and holds in solution a considerable
’ -quantity of extracto-resinous matter. If water beadded to
-this tincture, it turns milky, and the resin falls down of a
dirty white colour. ‘With a solution of sulphate of iron
the precipitate is green; with muriatic acid it is fawn-
leaving extract Coloured. The coffee exhausted by alcohol, and afterward
and mucilage. treated with water, still furnishes extractive matter and
mucilage,
San ciliate From these preliminary experiments | we may conclude,
principles of that raw coffee contains, 1. an aromatic principle soluble i in
water ;
ON COFFEE. Ob,
water: 2. a very small quantity of essentiai:oil: 3. a resin raw coffee.
in tolerable abundance: 4. a gum in greater quantity: 5.
gallic acid, but no tannin: 6. extractive matter: 7. a little
albumen.
Observations.
If the decoction filtered while hot become turbid on cool. General re-
ing, it is becanse it holds in solution by means of the heat a, BARRO Meme
little resin. Alkalis render it brown; their usual effect on
vegetable decoctions. Lime water precipitates it, because
on the one hand gallate of lime is formed; and on the other
the gummy extractive matter unites with the earth, and car.
ries it down. The same may be said of the sulphate of alu.
mine. Spirit of wine separates the mucilage, because gums
are not soluble in alcohol; and water precipitates the alco-
holic tincture, because resins are insoluble in water. This
precipitate by water is white in consequence of its extreme
division: by sulphate of iron green, because it is mixed with
gallate of iron: by oxigenized muriatic acid fawn-coloured,
because the oxigen, attacking the resin, sets bare a little
carbon, The insoluble scum formed on the surface of the ;
decoction is a little vegetable albumen coagulated by boiling
water. . To obtain this, it is necessary, that the water should
stand some time on the coffee cold, before it is heated.
Proportions by Approximation.
-Though it is not of much use to inquire into the pro- Proportions of.
portions of the immediate principles of coffee, since these #5 Principles. ~
proportions must vary as the berry is more or-less ripe, and
according to the place from which it comes, and the time it
has, been kept, I have deemed it not superfiuous, to esti-
mate them as nearly as may be. After several comparative
experiments I have found, that eight ounces of coffee afford
nearly _
oz. dr. gr.
Of mucilage - - - 100
Resin - - - - - 0 1 0
Colouring extractive matter - Or
~ Gallic acid - - tn I the:
Parenchyma - neg Dar 5 3 36
- “<Yegetable albumen - «= + O 010
lw 7 i 7
It
116 ON COFFEE.
Coffee germi- It has long been known, that coffee germinates in boiling
ei in boiling water (s¢e Bomare’s Dict. art: Café,) and I have verified
ater 5
but not in alco- this faet., But it does not germinate in boiling alcohol;
hol. either because the temperature is not sufficiently high, or:
because the water is necessary to its germination, or because
alcohol destroys its vegetative action.
Martinico and I have compared the decoctions and tinctures of three dif-
ok Na coffee ferent sorts of coffee; those from Mocha, Martinico, and
the Isle of Bourbon. The last two appeared to me to fur.
nish the same principles in the same proportions, but that of
Mocha differ. Mocha differs essentially from the others. Its decoction was
ent, much less saturated, its alcoholic tincture was higher co-
loured; it contained less gum and less gallic acid, but more
resin and more aroma,
Torrefaction.
To know what changes are produced in coffee by roasting,
I examined the phenomena that take place during its torre-
faction in the open air.
Fffect of reast- At first the coffee, being penetrated by the caloric, in-
ing. creases in bulk: it crackles, and becomes fawn-coloured:
the arillus or pellicle that envelops the seed, separates, and
as it is very thin and light the least: breath blows it away.
The coffee then diffuses a very agreeable aromatic smell.
This vapour grows more intense ; the seed smokes, and turns
' brown: presently the smell changes, and becomes slightly
empyreumatic; the coffee sweats, and becomes oily on its
surface *; it ceases to smoke, and if the action of the fire
~ be continued it is carbonized.
Diffcult to. The interval that separates the instant that the coffee be.
Toast it to a comes coloured from that of its carbonization is sufficiently
aie if i aia long, to render it difficult to determine the point at which
we should stop, in order that the berry may retain its most
agreeable properties ; but in order to approximate this point,
Fit oifin cof 0 (2% Mr. Parmentier wrapped up same roasted and sweating coffee
fee. in blotting paper, This paper, imbibing the oil, remained greasy
and transparent for more than a year, which indicates the existence
., of a fat oil in.the berry. I could not separate any such oil, how-
ever, either by pressure, boiling in water, or the action of caustic
_. alkalis.
which
Qtr
ON OOFFER. 17
which i is of so-much:importance to be known, { divide the Three stages of
process of roasting into “three distinct periods: 1, that in Cpe Beas,
which the berry loses its natoral colour, and assumes that
of bread raspings, or dried almonds: 2, that in which it
aequires the-brown red of a dry chesnut: 3, that in which,
become almost black, it is still not charred.
I took six ounces of Martinico coffee, divided them into Experiment.
three parts, and roasted them separately in these three de-
grees.
The two ounces slightly roasted, and of the colour of Lost of weight
‘dried almonds, lost on the fire two drachms. These I shall *°
call No. 1.
The two ounces roasted to a chesnut colour Lest three .3,,
drachms. These I call No. 2.
The two ounces roasted to blackness lost three drachms or near ¥.
forty-eight grains. These I shall distinguish as No. 3.
No. 1. passed through the mill with difficulty. Infused Slightly roast-
eold, the infusion contained tannin, and precipitated solu- a
tion of gelatine; it was very aromatic, * and had the fla-
vour of almonds; -there was not the least bitterness, but a
sufficiently decided harshness. Infused hot its aromatic fla-
vour was the same; and its taste reminded me of that.of
the almond cake called nowgaf. It was not at all bitter,
and the harshness was less perceptible.
No. 2. was more easy to grind. To cold water it gave Higher roasted.
out less tannin; its aromatic flavour was weaker, and ithad
,
* The object of retaining the aroma, which is dissipated by a Two methods
strong heat, has given rise to two processes, which are notalto- used to fetain
gether ineffectual, The first, adopted in India.and by some per- ease)
_ sons in France, consists in putting into the cylindrical roaster a lit- butter in the
tle fresh butter, when the cotfee begins to be coloured. No more Toasting ;
must be used than will slightly varnish the surface of the berries.—
The butter retains a part of the essential oil, that would have eva-
porated. Itisnot a bad.method, but sometimes it imparts to the
coffee a peculiar flavour, which every body does not like.
The second consists in spreading the roasted coffee, while yet hot powdering with
and sweating, on writing paper, and powdering it lightly witb su- SY" after it.
gar. The sugar absorbs the oi! of the coffee, and retains its aroma ;
but it does not appear to me to increase the pleasantness of the cof-
See, and renders us uncertain how much sugar to put into a cup.
mote
118 Ow COPERE.
more of’ the taste of burnt sugar, but neither bitterness nor
harshness. © Infused in hot water it A ibe out neither more
tastc, nor more aroma.
Very highly No. 3. was reduced to powder very iy To cold
nes. water itimparted scarcely any aroma: its taste’was empy-
, reumatic, and slightly bitter: and the precipitate it afforded
with solution of gelatiné was hardly perceptible. The in-
fusion in hot water was more Bitter, more empyreumatic,
and had a more distinct aroma.
Roasting in- All these infusions contained mucilage and gallic acid, but
creasedthe in an inverse ratio to the tannin; for the proportions of
Se ae a gum and acid increased with the degree of torrefaction,
tannin. while the tannin diminished.
Galite and = Mr. Bouillon Lagrange, in an excellent paper on galls,* :
eee of had already considered the gallic acid as a modification of
tannin; and these experiments tend to confirm his opinion.
- Examination of the Roasted Coffee. -
As the immediate principles of coffee are not equally so-
luble. or volatile, it was necessary to make a comparative
examination of the hot and cold infusions of the three sorts
of coffee, as well as of their decoctions. .
Infusion in Cold Water.
Roasted coffee 1 poured eight ounces of distilled water on one ounce of
— in yoasted and ground coffee, and after they had stood toge.
ther two hours, I filtered the liquor. The infusion was of |
a very clear brown, did not redden blue paper, was black. —
ened by sulphate of iron, and slightly precipitated solution
of gelatine, Alcohol separated from it a little mucilage, |
and gave the infusion the smell of juniper. Mocha, Bour-
bon, and Martinico coffee exhibited the same characters. —
Hot Infusion. :
infused, I infused an ounce of roasted and ground coffec for 4
quarter of an hour in eight ounces of water at 702 (190° F’.)
This infusion did not redden litmus, or precipitate solution
of gelatine, but formed ink with sulphate of iron, Alco-
* See Journal, p. 58 of the present Volume. T.
hol
ON-.COPFER. 9
hol separated more gum from it than-from.the cold infu--
sion. The three sorts of coffee comported themselves the ©
same in these experiments.
m4 Decoction. — aba
I boiled two ounces of powdered coffee in one pound boiled.
of water, and continued the boiling for two. hours, The
smell of the decoction was infinitely less agreeable and aro-
matic than that of the infusion. It did not change the co-.
lour of blue paper, or precipitate the solution of gelatine,
"but was blackened by sulphate of iron. Alcohol separated
from it much more mucilage than was found in the infusions, ,
in proportion to the quantity of coffee. The three sorts of |
coffee afforded the same results.
If a filtered and limpid decoction of coffee be boiled a Effect of ote
tong time exposed to the air, it grows turbid, and deposits Pins.
a black powder, which has sometimes been mistaken for
resin, but is only extractive matter highly oxigenized. Phy- j
' sicians and apothecaries have not yet sufficiently examined
the action of the air on vegetable decoctions ; but they might
derive from it some information respecting the more or lesa
active properties of certain medicines.
Extract of Coffee.
The decoction of coffee, when filtered and evaporated Extract.
to the consistence of an extract, has no longer the aromatic
odour of the infusion. Its taste is. bitter. Heated with
alcohol, this extract colours it with its extractive matter,
but the tincture affords no precipitate on the addition of
water. Hence we may conclude, that the decoction of
coffee, after it has been filtered or stood to settle, contains
no resin.
Spirituous Tincture of roasted Coffee.
Roasted coffee digested in alcohol affords a high coloured Tincture.
tincture, from which water precipitates a larger quantity aang aati
of resin, than from the tincture of dry or raw coffee.— raw coffee.
From the latter the resin. is white; from the tincture of ©
_ roasted coffee it is fawn coloured,
Observations
120 ON COFFEE.
Observations. |
Effects of It follows from thesc experiments, that roasting develops
Toasting. the odorant and resinous principles of coffee, and forms in
it tannin, which is soluble only in cold water. This is a
very singular phenomenon. Gallic acid manifests itself in
coffee, at every temperature of the water employed as a
menstruum. The gum and colouring extractive matter are
more abundant in the decoction than in the infusions; but
the aromatic principle is more perceptible and more agree-
able in the latter.
Distilled Water of roasted Coffee.
Water distilleg I distilled several quarts of water from roasted coffee.
from roasted ~=The water was impregnated with the aroma of the coffee,
toffee. : etait .
% and carried over with it some atoms of concrete essential
oi}, like that obtained from the distillation of raw coffee.
Reagents did not demonstrate the presence of any substance
in solution in this water.
Infusions and Decoctions compared.
“Treated first To find the different solubility of the principles of coffee,
with cold water it remained for me to subject the same powder of roasted
coffee to the successive action of infusion and decoction.
For this purpose I placed in a filter two ounces of coffee,
and passed cold water through it, till the reagents ceased to
indicate the presence of the matters insolution. Sixty-eight
ounces of cold water were necessary to divest the coffee of
al the matter thus soluble. I divided this water into seven-
teen portions of four ounces each, as they passed through
the filter. All these contained gallic acid in proportion to
the order in which they passed through: the first four took
up gum; but only the first indicated the presence of tannin,
by precipitating a solution of glue.
thenwithhot, The coffee having been taken out of the filtre, and dried
on a stove, I poured on it eight ounces of water at 75°
(201° F.) The smell of this secondary infusion was plea-
sant, but weaker than that of coffee prepared for the table.
Examined by reagents it furnished a little mucilage, and a
great deal of gallie acid; but I found in it neither tannin
nor resin,
. T took
ON COFFEE. 12]
i took this same coffee, already washed with cold water, and. lastly boil-
and infused in hot, and boiled it in six ounces of water, &4:
till they were reduced to four. This decoction contained a
great deal of gum and gallic acid, but little aroma, and af-
forded no trace of tannin or resin with reagents.
Observations.
These experiments prove, that cold water divests roasted Effects of
coffee of the little tannin it contains, of part of its extrac- sisegniscihie
tive matter, and of great part of its aroma; but that it
takes up only a small portion of its, gallic acid, and of its
gum. We perceive, that the hot infusion is more loaded of hot,
with both of the latter principles; but that its aroma is !
weaker. Lastly we find, that long boiling dissipates in a of boiling.
great degrce its odour, but is highly loaded with gum and
gallic acid. If it be found to contain resin, this is only
suspended in it, disturbs the transparency of the liquor,
and is deposited by standing.
| Ashes of Coffce.
Though it is of little importance to know what coffee Incinerated,
reduced to ashes contains, [ incinerated about half a pound. Soiesine Ia
The ashes were pretty light. Lixiviated with distilled water, r
their analysis afforded nothing but a little lime, and a very
little potash. J acidulated the lixivium with a small quan-
tity of nitric acid, and the filtered solution precipitated
prussiate of potash of a fine blue. Ovxalic acid gave with
_ it a copious precipitate. It was not altered by barytes.
“Nitrate of silver. turned it white. Coffee ashes then are contain Garber:
composed of carbon, iron, lime, and muriate of potash. iron, lime, and
muriate of
ged did not think it necessary to ascertain their proportions. pgsash.
“I had intended here to have concluded my analysis, when Coffee analysed
Mr. Parmentier read at the Society of Pharmacy a very by Mr. padi
copious memoir on coffee, written by Mr. Payssé, -an
apothecary, who has already published several very inte-
resting works. It is said in this memoir, Ist, that the pre-
cipitate formed by the mixture of the decoction of cofiee*
_ * This is a mistake. It was the precipitate formed by the acid
of coffee, as Mr. Payssé calls it, obtained in the way in which
Mr. Chenevix found what he considers as a distinct principle, by
precipitating the decoction with muriate of tin, and separating
the tin by sulphuretted hidrogen. T.
Vou. XVII.—Jury, 1807. K with
122 ON COFFEE.
with sulphate of iron, is soluble only in the nitric, sul-
phuric, phosphoric, and oxalic acids: 2d. that coffee con-
Contains a pe- tains no gallic acid: 3d. that it contains a peculiar acid,
a sué generis, which the author calls coffic acid, and which
he obtained by following the process of Mr. Chenevix, that
is, making a decoction of raw coffee, filtering, precipitat-
ing by muriate of tin, and decomposing this precipitate by
sulphuretted hidrogen gas *.
The authority of the name of Chenevix, and the ac-
curacy with which the processes of Mr. Payssé are
generally conducted, induced me to make several ex-—
periments, in order to confirm the new facts that were
announced. |
Decoction. I boiled two ounces of Bourbon coffee in a pivt of water,
for two hours. The decoction exhibited the same pheno-
mena as I had already observed. It assumed a yellowish
green colour, which became more bright by the separation
of the little albumen, and let fall a precipitate of oxige-
nized extractive matter. This decoction, when filtered,
turned the aqueous tincture of litmus green.
Precipitated by I mixed a portion of this decoction with a solution of
riage of sulphate of iron, and obtained a precipitate of a very
deep blue, inclining to black. This precipitate I redis-
solved in oxigenized muriatic acid, strong and weak acetic
acid, tartarous, citric, and even benzoic acid.
and by muriatic Muriatic acid rendered the liquor yellow ; but it resumed
oe its transparency, after letting fall a tolerably heavy pre-
cipitate of oxigenized extractive matter. This precipitate,
being redissolved by ammonia, gave a fine brown red
colour to the liquor.
Precipitate by The immediate precipitate of the sulphate of iron dis-
sulphate of solved by acetic acid, comported itself nearly in the same
Bias manner, except with regard to the colour, which was of a
violet blue. It was likewise redissolved by ammonia. The
and by acids. other acids afforded nearly the same precipitate as the mu-
* Mr. Chenevix does not say, that the substance he obtained
by this process was an acid, but a new product, the nature
of which he does not determine. [See Journal, Vol. II.
p. 114.9
riatic ;
ON COFFEE. 123
riatic; their action in general being in the ratio of their
acidity.
I treated a precipitate of sulphate of iron, obtained by The précipitate
meansiof gallic acid, in the same manner, and the results ees bi
were no way different from the preceding. ay
The remainder of the decoction of coffee I precipitated Precipitated’ by
by muriate of tin. This salt occasioned a very copious ™* of tin,
sediment in the liquor, which I washed with water, till no
marks of acidity were perceptible in it. I afterward put
this metallic compound into a tubulated phial, and poured on
it a considerable quantity of distilled water. 1 then and the tin
adapted the phial to a Woulfe’s apparatus, so as to pass eal ee
sulphuretted hidrogen gas over the precipitate. The first hidrogen,
portions of gas changed the mixture brown, and this colour
grew deeper and deeper, in proportion as the liquor be-
came saturated with the gas. The precipitate was de.
composed: a hidrosulphuret of tin was formed: and the
disengaged acid was taken up by.the liquor. The liquor,
being first filtered, was evaporated by a gentle heat, till it
was reduced to one eighth. This product, considered by
Mr. Payssé as coffic acid, appeared to me to be nothing but Not. a peculiar
gallic acid. JI not only subjected it to the action of all the cit =
reagents comparatively with acid obtained from galls in the Proofs;
usual way; but, that I might leave no doubt on this head,
I treated galls by the same process. In this decoction the
muriate of tin formed a more abundant precipitate than in
the decoction of coffee: the precipitate, decomposed like
the preceding by sulphuretted hidrogen gas, afforded me an
acid of the same colour, the same taste, possessing the
same properties, and differing only in quantity. I think,
therefore, I may conclude, that the cofic acid does not
exist; but that coffee contains less gallic acid than nut-
galls. :
It is possible, that this gallic acid may exhibit in its com- May have some
binations and compounds some slight shades of difference jee ate
_ from the acid obtained from the gall of the oak, but it is obtained from
uevertheless of the same nature. . Peet
The immediate materials of vegetables, as is well known, as is the case
though of the same kind, and perfectly analogous, are not ppt
strictly identical. The gums and sugars exhibit differences ciples of vege-
K 2 in, tables.
124 ON COFFEE.
in their physical properties; yet all mucilage, all saccha-
rine matter, is the same chemically considered*. Proust
has demonsirated, that tannin obtained from different vege-
tables displayed some differences: it is possible, therefore,
that gallic acid obtained from coffee may not be absolutely
the same as that from galls, but it is not a distinct acid.
Recapitulation.
Principles of It appears to be demonstrated from the analysis above
sates given, that the coffee berry contains abundance of muci-
lage, a great deal of gallic acid, a resin, a concrete. es-
sential oil, albumen, and a volatile aromatic principle.
To these principles are added those found in many vegeta-
Effects of roast- bles; namely, lime, potash, iron +, carbon, &c. Torres
ng: faction develops the soluble principles; but it must be
moderate, if we would retain the aroma, and not decom-
pose the acid, the gum, and the resin.
Tannin pro- The roasting adds a new principle, which is tannin,
duced by it. X ; ‘ 5 :
Treated with though in very small quantity. The cold infusion is very
water. aromatic; but it contains little mucilage or gallic acid.
The hot infusion retains some of the aroma; and the prin- |
ciples dissolved in it are in such proportions, as to be agree-
able to the taste. The decoction has little aroma, and is
much loaded with gum and gallic acid, the resin too may
even be suspended in it, and it is less pleasant to the taste
than the infusion.
ee sorts The coffees from the island of Bourbon and Martinico
or coitee,.
*'The fecula of potatoes does not resemble that of wheat, and
this again differs from the fecula of cassada, sago, salep, arum,
maize,: &c. - Yet chemists would say of all these, that it is an
amylaceous substance, and find in them the same leading cha~
racters,
Iron in coffee + The presence of iron in vegetables is very common ; but that
with gallic acid, of iron in a vegetable containing a great deal of gallic acid, with-
be be auoue out this acid being combined with it, and imparting a blue or
black colour to the vegetable, is a very remarkable phenomenon.
It appeared to me deserving of i inquiry, and I made a coniparative
analysis of the ashes of galls, in which also I found a sensible
quantity of iron. [It may be observed, however, that galls have
very often an evident blue tinge; so much so, that it is commonly
considered as an evidence of superior quality, T.]
do
ON COFFEE. 125
flo not perceptibly differ from each other; but that from
Mocha, as was observed above, is more aromatic, less
gummy, and more resinous. It is probable, that the resin Perhaps the
of coffee, as that of most astringent vegetables, has pecu- ‘ medicinal.
liar medicinal properties. As it is obtainable neither by
infusion nor decoction in water, the habitual use of coffee
_ can afford us no insight into its action on the animal eco-
- nomy. Itis for physicians to make such experiments on
the subject, as they may deem useful.
If I might be allowed from this analysis to draw pre- Domestic use
cepts applicable to the domestic use of coffee, I would say, peceerss
that it is possible to make excellent coffee from every kind
of the berry found in the shops, provided it be not damaged.
Amateurs look to three points of perfection in coffee:
‘they would have in it an agreeable aroma, a slightly rough
taste, and a certain density, which is called body*. All
thése objects, I believe, may be obtained, by proceeding
as follows.
1. Choose a coffee, that, when dry, has no taste of ae aoe
mouldiness, or is not damaged by salt water. greatest perfec-
2. Divide the quantity to be roasted into two equal tion.
parts.
3. Roast one-portion only till it is of the colour of
dry almonds, or bread raspings, and has lost one eighth of
its weight.
.4. Roast the other till it is s of a brown chesnut colour,
me has lost nearly one fifth of its weight.
. Mix both these together, and then grind them.
; Let the coffee be both roasted and infused the day’ on
which it is to be drunk.
7. Pour four cups of cold water on four measures, or
two ounces of coffee, and when the water has run off, set
it by.
8. On the same coffee pour three cups of boiling water,
and mix the water that runs off with the preceding. You
should thus have six cups of coffee. :
~ * Some of the eastern nations value this density so highly, that
they reduce their coffee to a very fine powder, leave the grounds
in the infusion, and drink it as thick as a kind of thin pap.
9. The
126 ON COFFEE.
9. The moment you are going to drink the coffee, heat
it over a brisk fire, but do not let it boil.
10. The infusions should be made in a china, earthen-
ware, or silver pot.
Such is the process pointed out by theory, and I can re-
commend it from experience.
——samentiniininss—=
Paysse's analy To give the whole of Mr. Payssé’s memoir, alluded to
sis of raw coffee.
' above, would occupy too mueh room; but we apprehend
— it will be acceptable to the reader, to have subjoined the
conclusions which that gentleman draws from his chemical
investigation of raw coffee; particularly as he differs, in
‘some respects, both from Mr. Cadet, and from Mr.
Chenevix.
It contains a 1. Jt results Froein all these experiments*, that coffee
acunecaed, contains a peculiar acid sufficiently characterised: that it is
‘in some respects free, since the powder of the berry speedily
reddens blue vegetable tinctures: and that cold. water, or
even alcohol, can separate it in a state more or less pure.
which decom- * 2. That the acid decoction of coffee easily decomposes
fallte solusiohs most. of the metallic solutions, as those of aes lead,
iron, &c.
Precipitates of 3. That the precipitates obtained by a mixture of this |
ince dca decoction with the metallic solutions are more copious
copious, be- than those formed by the pure acid, because the decoction.
cause less pure. contains extractive matter, colouring matter, albumen, .&c.
~ beside the acid. For the colouring matter is partly preci-
pitated by the affinity it has for the compound, formed of
the coffic acid with the metallic base; and on the other
hand the albumen, being separated from the acid which
promoted its solution in the liquid, falls down and in-
creases the bulk of the precipitate. To be convinced of -
the truth of this, nothing more is necessary, than to boil
a coffat of tin, lead, or alumine, in a coloured vegetable
decoction, to obtain the result in question.
Methods of ob- 4. That the acid of coffee may be obtained sufficiently
bg oy pure by mixing a decoction of coffee in water, ora tinc-
ture of it in alcohol, with the muriate of tin or of lead,
and afterward deco:aposing this combination by sulphuretted
* Annales de Chimie, Vol. LIX. p. 196. August, 1806,
hidrogen,
ON COFFEE. 127
hidrogen, as Mr. Chenevix did; or by decomposing coffat
of lead by the sulphuric acid.
5. That this new acid is not crystallizable in the state in It is soluble in
which I obtained it; but is completely soluble both in ene mr
water and in alcohol.
6. That it is capable of decomposing the prussiate of Decomposes
iron contained in the prussiate of potash, forming with this alps pad
metal a green precipitate: and in this respect it may be of @ green preci-
great service to chemists for obtaining prussiate of potash P ii.
perfectly pure, which hitherto they have been unable to
deprive of a certain portion of iron, it retaining this with
so much obstinacy.
7. That the colour it communicates to the oxigenized Its effects on
and green sulphate of iron appears altogether new *. idol e
8. That the attraction of the compounds it forms with May be of use
tin, lead, antimony, and alumine, for the colouring parts 4 mordant.
of vegetable decoctions or infusions, may render it of use
in the art of dyeing.
9. That the different kinds of coffee contain it in nearly In all kinds of
the same proportion; and that it exists without alteration, aioe a ah
though in smaller quantity, in the infusions and decoctions
of coffee roasted in different degrees, as well as in the pro-
ducts of its distillation.
10. That the comparison I made of the properties of Differs both—
this acid with those of the gallic acid and tannin did not fom salle acid
show me any identity of nature between these three very
different substances.
11. That the peculiar principle obtained by Mr. Chenevix !t ie the a
was, no doubt, the acid substance in question; though it Gbiaiied ty :
was not examined with sufficient strictness by that learned Chenevix.
chemist.
_ 19. That, having examined the infusions and decoctions No tannin in
of different sorts of roasted coffee, they did not afford me ogi den oom!
any proof of the existence of tannin, by mixing them with
gelatine, as Mr. Chenevix asserts.
* Coffic acid, dissolved in six times its weight of water, added
to a solution of oxigenized sulphate of iron, immediately gave it
a fine green colour; and after it had stood six hours, a precipitate
of the same colour fell down. ‘To a solution of green sulphate it
gave at first a very light green tinge, but this grew deeper, after
it had been some time exposed to the air.
13, That.
128 ON PLATINA.
Coffic acid 13. That the acid of coffee is capable of uniting with a
Es. great many bases, and forming peculiar salts, decomposable
with more or less facility by fire, and the powerful acids ;
and that its affinities appear to follow a law altogether dif-
ferent from that of most of the known acids, since its
but most feebly union with alkalis seems to be the weakest.
weed ivesed 14. That it is decomposed by hot sulphuric acid, and the
and reduced to nitric, muriatic, and oxigenized muriatic acid ; and reduced
=i re by the latter, as well as by the nitric, to malic acid.
Contains much 15, That, from the products obtained by its analysis by
Bile hitoeen: fire, it appears to be composed of a great deal of carbon,
with less hidrogen and oxigen.
Component 16. That 100 parts of aqueous extract of coffee, the
nine oe product of about 750 parts of the berries, afforded me o¢
coffic acid 55, extractive matter 25, vegetable albumen 5, and
resinous matter 9; the loss being 6.
17. That, to adopt the language of modern chemistry,
this acid ought to be called the cofic, from the name of the
substance from which it is taken.
Ashes. 18. That the incinerated residuum of coffee is composed
of muriate of potash, lime, and a portion of iron, the
quantity of which was too small to be ascertained.
Remote princi- 19. Finally that coffee, from all that has been said, is a
ples of coffee. substance containing carbon in much larger proportions
than hidrogen, oxigen, or azote; the existence of all these
having been evidently demonstrated by the formation of
oil, pyromucous acid, carbonic acid, and ammonia united
with this acid, in the destructive distillation of coffee.
fen Va caet _———$$<$< <<< ——— ar
Account of the Existence of Platina in the Silver Mines of
Guadalcanal, in the Province of Estremadura. By
M. Vavquerin*.
Leite: 9 Hiruerro platina had been found only among the
Athesion., gold mines in South America, at Santa Fe, and in the bai-
liwick of Choco. There was a report a few years ago,
* An. de Chim, Vol. LX. p.317, Dec. 1806,
that
ON PLATINA. j29
é
that platina had been discovered in Siberia; but this has
no more been confirmed, than that spread fifteen years ago,
of its existence in a ferruginous sand at St. Domingo.
Having been lately employed to analyse the ores of the Pie neat in
celebrated mines of Guadalcanal, in Estremadura; which, i Ri,
after having been shut up for a long time, have lately been ed, finish
‘opened again at a fresh place; I discovered in one variety ape
of these ores the presence of a large quantity of platina.
This ore is of a gray colour, and bears considerable’ re- from a variety
semblance to that known in France by the name of gray ties ae
silver ore, the fahlerz of the Germans, [properly gray
copper ore.| It contains copper, lead, antimony, iron,
sulphur, silver, and sometimes arsenic. Its gangue most
commonly consists of carbonate of lime, to which are
added sulphate of barytes and quartz. Jn the month of
October last, I communicated this discovery to my learned -
colleague, Mr. Fourcroy, whose knowledge and friendship
have been continually serviceable to me for these twenty
years. This fact, which appeared to-him highly important,
he persuaded me to verify, by experiments so numcrous
and varied, that they should be open to no dispute. TI fol-
lowed his advice; and the following are the results of my
researches, which have left no doubt in my own mind,
though hitherto I have been’ able to operate on no con-
siderable quantities of ore.
The platina appears to exist in various proportions in It is in various
the silver ores of Guadalcanal. Some specimens afforded from 10 pox
me as much as twenty marks to the hundred pounds, or ten cent. to almost .
per cent; and some exhibited merely traces of it, that ee
were scarcely perceptible; which indicates, that it does
not form an essential, or properly constituent part of the
ore, and that it is simply mixed in irregular quantities in
various parts of the vein. The silver appears to be in cole aie
the same case. - In fact this varies greatly in its proportions, seven eek be
as I have found in the gray ore of Guadalcanal from four cent.
marks to fourteen, or from two to seven per cent of the
whole weight.
The process I employed to extract the platina from these Mode in which
ores, after ‘several comparative trials, consists in the fol- WN ip a tad
Jowing operations. 1. After having reduced the ore to a
fine
130 ON PLATINA-
fine powder, I roasted it with a gentle heat, stirring it con-
stantly, to avoid the fumes. 2.1 then fused it with an
equal quantity of common potash, and thus obtained a
metallic button, consisting of platina, silver, lead, copper,
and sometimes a little antimony. The iron and part of the
lead remained in the scorie. 3. I then separated the copper,
antimony, and remainder of the lead, by cupellation;
which left me only the silver and platina. 4. I parted
the platina from the silver by means of aqua fortis, or the
nitric acid of the shops, which dissolved the silver, and left
the platina behind. This I washed, and heated again, to
give it the metallic lustre. 5. If the lead naturally found
in the first metallic button were not sufficient, to carry off
all the copper in the process of cupellation, I subjected
the metal to this operation a second time with a fresh por-
tion of lead. 6. On the contrary, if the quantity of silver
were too small to allow the aqua fortis to act on the alloy,
I added a fresh portion of this metal, as in parting it from
gold. 7. lought to caution the reader, that the aqua fortis,
if it be not sufficiently diluted, will dissolve a portion of
platina at the same time with the silver; which is easily
perceived by the brown colour the solution assumes.
Partingneces- If platina be found in the gray ore of Guadalcanal in
ena a proportion that will allow it to be extracted with ad-
andeven tle vantage, of which, according to my first researches, there
siUSBe. cau scarce be any doubt, it will require to be parted by
means of aqua fortis, in the same manner as is practised
with respect to the gold extracted from silver ores: and
even if there be no advantage to be derived from the pla-
tina extracted by this process, it will be necessary to employ
it to obtain the silver; for by any other mode these two
metals will be found united together from the similarity of
their properties.
It isinthe me- Platina appears to exist in the metallic state in these ores,
tallic state. for the simple acids do not dissolve the smallest quantity of
it, and it is constantly found among the sulphur and silex,
when the latter constitutes part of the gangue. It was in-
deed by examining these residuums of the ores, and treat.
ing them in succession with nitric and muriatic acid, that I
first perceived the platina.
What
CARBONIZATION OF TURF, 131
What is remarkable on the present occasion is, that Neither of the
neither of the four metals recently discovered, which ac- pidgin et
company platina in the ore from Peru, is found in that of
Spain. This is’ a consideration of much importance, since Will afford
it will greatly influence the means of extracting this metat, Pure Platina.
and sifice it gives hopes of obtaining it in a state of purity,
which cannot be attained with the platina of Peru, but by
means of difficult processes and great expense.
If these hopes be realized, as every thing tends to per-
suade us, we shall have in Europe, and at hand, a precious
metal, which will soon become of great utility for the
purposes of natural philosophy, chemistry, the arts, and
even domestic economy, in fabricating a variety of in-
struments, vessels, and utensils of every kind; since, with
all the advantages that gold enjoys, it unites several pro-
perties, that render it greatly superior to gold*.
ne
Carbonization of Turf, or Process by which all possible
Advantage may be derived from Products hitherto neg-
lected in that Operation, executed in the Year of the
Republic 11; by Antony Tritiaye-Prater, House
Apothecary at the Hotel-Dieu at Paris t.
‘Lun idea of the experiments, of which I am going to
give an account, was suggested to me by the discovery of
thermolamps.
* Perhaps this discovery of Mr. Vauquelin may account for the Ancient
two ancient candlesticks in the cathedral of Hildesheim, in Lower C@™dlesticks
“Saxony ; made we believe long before any platina could be brought Pro°ably fom
Saxony ; made we believe long before any platina cou MEH sie same, of 2
from South America, though we do not know their exact date ; similar ore.
and mentioned by Professor Cramer, of that place, in his Letters
on Natural Philosophy. "These are described as white, and nearly
as heavy as gold, and probably therefore consist of such an alloy
as would be obtained from a portion of the ore of Guadalcanal,
_ rich in platina and poor in silver; and which Bishop Bernward,
their maker, though one of the most skilful metallurgists of his
time, did not know how to.separate. T.
+ Annales de Chimie, Vol. LVIII. p. 128, May, 1806.
: I was
182 CARBONIZATION OF TURF.
Manufactory I was at Rouen, employed at the hospital under Mr.
Epp Apneeee Robert, chief apothecary, a man for whose talents I have
the highest respect, on more accounts than one; and he was
repeating some experiments relative to these discoveries,
which when I saw, I conceived the idea, that the apparatus
might be employed for more carbonizing processes than
one; and I communicated to him my thoughts respecting
some questions, that had been put to me, on the possibility
of converting turf into a charcoal, capable of being sub-
stituted for that wood.
It had been proposed to me, to form an establishment
capable of manufacturing a very large quantity at a time.
Mr. Robert approved my scheme; and, assisted by his ju-
dicious adyice, I undertook a dak teaigite of turf charcoal
some miles from Gournay.: |
I had already obtained some success, when circumstances
foreign to the business occasioned it to fall to the ground,
and ruined an undertaking on which I had tong rested all
my hopes.
Though J] here bring forward new methods, it does not ©
follow, that the product of some manufactories, among
others those of Meaux near Paris, are not of good quality,
as the public begin to be sensible.
Turf first In order that the turf may present the greatest possible
pressed. substance in a given bulk, I expose it to a regular con-
tinued pressure; by which means it quickly loses all the
water it contains, its desiccation in the air is more speedy,
and thus we gain the advantage of a saving of time.
Mode of After this pressure, though the charring might be per-
vals to be formed without this preliminary operation, care is taken to
place the turfs so, that the masses they form shall present
demiobstructions to the air, to accelerate its currents.
In this state it is subjected to carbonization by means of
an apparatus, which will be described below.
Products by Observation having proved, that vegetable substances
distillation. "afford advantages even in their distilled products, I con-
cluded, that the oily and condensable matters should be se--
parated from the gasses, which I intended to employ as a
supplementary support of the combustion.
The gasses This observation is so much the more valuable, as these
supply fuel. very
CARBONIZATION OF TURF. 133
very gases may supply the place of one fourth of the turf
or combustible employed in the carbonizing fire, an ad-
vantage hitherto neglected.
_ [would beg leave here to remind the reader of some facts
relative to the order in which the gasses are disengaged,
during the action of caloric applied to vegetable sub-
stances.
It is known that caloric, in contact with these vegetable Effect of ca-
substances, disorganizes them wholly or in. part; that it !°t-
solicits their three remote principles to combine according
to their various affinities, and at different temperatures ;
and that the results are products very different from the
original compound.
Thus, for example, the most volatile substances, or First products,
those the principles of which have the strongest attraction ceil oil, and
for each other at a low temperature, are first disengaged: ’
the water,’ oil, and vegetable acid, pass over first, whether
they were partly contained in’ the vegetable substance, or
that their priticiples were induced to combine by the pre.
disposing affinity of caloric: but at a high temperature, at
a red heat, carbon decomposes water, this ceases to’ be then carbonic
formed, and the carbonic acid passes over, with carburetted id, and car-
y y buretted hidro-
hidrogen surcharged with carbon, and oxidule of carbon}; gen.
the fixed substances remain in the distilling apparatus; and,
if azote be contained in these substances, it is at this period
the carbonate of ammonia is disengaged.
- Though the phenomena take place in this manner, in small Carbonization
masses, heated equally in all their parts, it is not the case hala
with several hundred weight of materials, the outside of
which will be carbonized, while the centre of the mass has.
scarcely experienced the effect of the caloric acting in the
inverse ratio of the square of the distance. F
Accordingly we may expect to find the products differing Proportions of
in their proportions at different periods: then the water, eet Gee
oil, and acid, will predominate at first, and will subse-
quently decrease in their proportions, and be more car-
- bonized. ;
We shall then find a black, oily, acrid substance appear, Empyreumatic
more or less heavy, which is the empyreumatic oil, and in-°!!-
dicates a carbonization approaching its end. in a favourable
manner.
The
1S4
Charcoal.
The furnace
described.
The ash-hole.
The fire-place.
Chimney.
CARBONIZATION OF TURE.
The last result is a fixed black substance, tolerably homo-
geneous, and weighing more than an equal bulk of charred
wood. Frequently, in consequence of the sand, the oxide
of iron, and the compactness acquired by the previous
compression, this substance is the true charcoal of turf;’
which sometimes, before it is obtained, furnishes a certain
quantity of sulphurous acid, arising from the combustion
of the sulphur and sulphate of iron contained in such turf
as [have dug. ‘This justifies to a certain degree the com.
plaints of persons, who refuse to make use of this com-
bustible; but this slight defect may be removed by very
easy means, which I employ in burning turf in rooms,
and of which I shall give the particulars hereafter.
I shall now give a description of my apparatus, which I
shall divide into two parts; the first describing the furnace,
the second the interior part, which I call thermolampi¢.
The furnace is square, terminating. above in an arch;
and in the front appear three apertures, one over another.
Its inferior part, in which is the ash-hole, is shaped in-
teriorly like a wedge, the base of which is the aperture,
one of the square sides lying uppermost and horizontally,
the other, an inclined plane, forming the bottom. This
form prevents any ashes from lodging in it to obstruct the
fire, and renders the current of air more rapid. It is
obvious that the upper part of this ashshole is formed by
the grate, which consists of movable bars of iron arsanged
parallel to each other by means of a cross piece. . This
arrangement facilitates the arrival of the air, and accele-
rates the combustion. Above the ash-hole is the second
opening, which is that of the fire.place, and is carefully
closed with a large stone shed with iron, and furnished
with two rings, to admit a hook, by which the door is-re-
moved whenever fuel is to be thrown in. See Fig. 2.
Plate ITT. bia
The third aperture is perceptible only by the-projecting
part of the bottom of the chimney, which suggests that
the smoke is obliged to surround the interior apparatus:
and this is in fact the case, since it returns to find an exit
exactly on a level with the bottom of the thermolamp,
which is supported by the interior and anterior part of
the furnace.
\
By
CARBONIZATION OF TURY.
By the chimney it may be observed, that the superior
aperture is less than the inferior, which is indispensable in
this construction; and this leads me to say,, that there al.
ways exists a direct ratio between the apertures of the fire-
place, the ash-hole, the place where the smoke enters into
the chimney, and that at which it finds its exit, which
should always be proportional to the height. Thus ash.
holes of a moderate depth and aperture, fire-places narrow
and well closed, turns (chicanes) artfully managed, and a
convenient issue for the smoke, all united constitute a
- furnace, the good qualities of which are demonstrated by
experience. Sce Fig. 1.
The second part of my apparatus, which I call thermo. Thermolamp.
lampic, is so arranged, that its lower part is horizontal,
and forms a long square. The upper part of its whole
length is an elliptical arch, terminated at each extremity by
a vertical plane, in the middle of which is a funnel or tube
bent at a right angle, serving to convey the products that
arise by distillation into the middle of a condenser, con- Condenser.
sisting either of a stone hollowed out, and covered by a
plank well luted to it, of a small wooden cask standing up-
right, or of a cast iron tube surrounded by a stream of
water. From these issue tubes to convey the inflammable Gas pipes.
gasses into the fire-place, that they may serve, as I men-
tioned above, instead of part of the fuel employed. The
funnels above described are furnished cach with.a key, to
intercept the communication between the outer air and the
charcoal, while stili hot: for experience has proved, that
charcoal thus prepared is capable of spontaneous aceension.
_ This phenomenon, it is said, may take place in large heaps Cirarcoal
kindled spon-
taneously.
ef charcoal long prepared; and, though I confess I never
saw such an accident, it is certainly prudent to guard
‘against it by currents of cold air traversing the heap in
-warious directions. See Fig. 3.
The material of which the thermolampic apparatus is Materia’.
composed should be sheet iron, or thin cast iron; though
one or more common cylinders may be substituted instead,
placed in a suitable manner, and furnished at their extre-
mities with tubes for conveying off the gaseous products,
&e.;.taking care that one end may be opened by means of
3 a hook,
136 CARBONIZATION OF TURF.
Opening for a hook, and closed with a proper lute. To all these must
—eipderay be added, that the part of the furnace, through which the
substance to be charred is introduced, should be made only
of dry bricks, and covered with wet clay.
Position of the Whatever be the form or material of the thermolamp, it
appara ought always to be placed horizontally in the furnace, and
have its extremitics resting on the side walls. “In this. situs
ation the bottom and circumference will receive the action
of the fire, which must be fed with the bad turf, as I have
mentioned, assisted by the gas from the lateral tubes.
Bar itor seen To all this must be added @ bar of iron, in the direction
rity. , of the width of the apparatus, to prevent it from giving”
way when loaded, and long exposed to heat.
Turf dried by I have turned the heat arising from the smoke to great
the ies of the advantage, by constructing a kind of stove, to prepare the
eos turf for the charring apparatus. The most suitable means
for this drying process, particularly in winter, may readily
be conceived.
Sixty pone Into an apparatus disposed as I have described, I put
of wood char upward of sixty pounds of dry wood, that I might form
aes an accurate idea of its advantages; and the following were
the results.
Results of the After having commenced the extrication of the gasses
process. with turf of good quality, acquired by pressure, they.
burned with vehemence, and at the expiration of an hour
furnished such a quantity of radiant heat, that the tubes
alone, without any addition of fuel, were capable of con-
tinuing the operation, affording in the conclusion a perfectly
homogeneous charcoal; and I confess, that I never saw
what appeared to me a more beautiful sight. How indeed
can we behold without admiration a combustible burning
itself, and thus saving half the fuel, that would have be#n
required to convert it into charcoal? |
Tiomestic ast I must not here omit to speak of the use of pressed turf
of pressed turf. for domestic purposes. For instance, I have found by ex-
perience, that turf of a good quality, after having been
pressed and well dried, “agietaie gr heat in the following pro-
portions.
Compared with Five or six parts of turf are equal to four of wood, sup-
wood, posing the fireplace to be extremely accessible to air. There
is
7
CARBONIZATION OF TURF. 137
is a great advantage in burning turf therefore, supposing it
even not to be pressed, and that in this case it would re.
quire two, three, .or even four parts to one of wood; for,
if we consider the value of both, we shall ‘find, that for
the same price three times as much turf as wood may be
burned.
But the public are unwilling to adopt this economical Objections to
practice, alleging, that turf emits a disagreeable smell *, i
and gives but little heat.
All these errors would be dissipated, if fire places were Not valid in
constructed nearly like those used in England for burning ie ine
coal or coak; and I may add, that I have had the pleasure
of seeing persons, who were greatly averse to innovation,
rejoice at having made trial of a fire place of my construc-
tion, for the use of a species of a fuel on which they would
scarcely deign to cast aneye. See Pl. IV. figs. 4, 5, 6.
Turf does not always afford an equal quantity of char- Proportions of
coal, and of course the quantity of ashes must vary in the pps ee one
same proportions. I have seen turf that afforded 0°38 or duced from
0:40 of charcoal, which left on incineration 0-17 or 0:18 of 5
ashes. I do not mention certain kinds, that have produced
0:50 of ashes, since from these must be subtracted 0:35 of
ferruginous sand, which they contained.
The turf that I employed in my manufactory produced,
after a well managed process, from 0:38 to 0:42 of char-
coal, and yielded from 0:13 to 0-16 of ashes; but [ am in-
clined to think, that, when the saving occasioned by the
use of the gases is considered, the quantity of charcoal may
be raised by secondary improvements to 0°50. The quan.
tity of ashes produced by turf charcoal will be thought
very considerable, when compared with the quantity arising
from sound wood. Thus on examining oak freed from its and from oak.
alburnum, and of fifty years growth, we find that fifty parts
yield from twenty to twenty-one of charcoal, and from two
to two and a half of ashes.
Finally I will add, that pressed turf, or turf of a very Turf may be
good quality, may be used in burning bricks .or tiles; and ¥5¢¢ in making
bricks, tiles, or
in baking common earthen-ware, &c. for three fourths of earthen ware.
* This smell is produced only by unprepared turf.
Vou. XVIJ.—Juty, 1807. L the
138 CARBONIZATION OF TURF.
the process, finishing it with one fourth of well burning
wood; and this earthen ware wil! be equal to what is com-
monly made for domestic purposes, as I have found by ex-
perience,
To obtain such results, I have myself oniiiaktad a fur-
nace on the principles laid dawn above. . Neither was the
preparation of the earth for each kind of pottery forgot-
ten: this was the basis of my labour.* ¥
Oily products. | [ have already observed, that the oily products received
in the condenser might be turned to advantage. These pro-
ducts are frequently divided into two strata: the first water,
impregnated with a small quantity of a light oil, and con-
taining acctous or acetic acid: the second a black, heavy,
acrid, very penetrating oil, thick like tar, and difficult of
solution. This may be used for various purposes.
Acid useful for The rectification of these oils furnishes a certain quantity
making: won- of acid, by means of which I have prepared the solution of
iquor, fordyers ,
or calico print- iron, cision in manufactories iron liquor; but it is proper
= to add a little concentrated acetous acid, in order to pre-
vent the precipitation of the iron in the state of oxide.—
With a solution of this sort I have prepared by a particular
method patterns of black, on cotton, silk, and woollen,
which were not inferior to those dyed in the usual way. 1
could likewise produce very good nankins ; and the buffs on
printed calicoes might be prepared with iron dissolved in this
acid, thickening the composition with starch or gum, ac-
cording to the value of the article and the tint required.
What I have said respecting iron dissolved in the acetous
acid may be extended to the employment of the empyreu-
matic oil in dyeing wool, &c. and a number of other pro-
cesses, too many to enumerate.
atl manninc. Lastly, Iam persuaded, that it is possible to oxide cop- -
turing verdi- per by means of this acid, which however is afforded in
se smaller quantity perhaps by turf than by wood.
Improvement | *1 would beg leave to mention an improvement I proposed in
in tiles. tiles, and which I carried into execution. ‘This consists in making
a tongue to them of a triangular shape, the base being very large
and at bottom; and with respect to the moulding, it may be suffi-
cient to say, that two men could do the work of toi in a given
time.
To ~
CARBONIZATION OF TURF. 139
To produce that preparation of copper, lech ‘is called sre pressed j
verdigris, the remains of certain cider apples might be used, pie Lasphien:
after the juice has been pressed out, of which there isa great ble to this pur
deal throughout Normandy, that is turned to no account, di
‘except as a bad kind of fuel. In this case it should be
moistened with bad sour cider immediately after it is taken
_ from the press, and put into earthen pots, or little casks,
, with plates of copper, stratum super stratum; washing the
oxided copper with our acid, after it has thus stood a month,
and then proceeding according to the method of Mr. Chap-
tal. Various wild fruits, as the sloe for example, might be and many wild |
used in asimilar manner, instead of the refuse of the neg
press.
I am indebted to Mr. B. E. Lefébure; my friend and
countryman, and a zealous cultivator of chemistry, for
the first idea of employing the pressed pulp of apples in pre-
paring the acetate of copper.
The facts related in this paper will prove interesting EF
hope to science, and of some utility to the public; and if
I meet with the reader’s indulgence, my wishes will be gra~
tified.*:
. Explanation of the Figures.
Plate Wl. Fig. 1. an interior view of the furnace, Explanation of
Q, Q, upper part of the furnace. aici
M, M’, the chimney, the shape of which may be-varied.
seas iy) ia :
. Be thet gael rhe \ to strengthen the apparatus.
L, L, little air holes, to accelerate the combustion at
sieeve: 2
q’, the fire-place closed by a abe with two rings, to ie
mit the introduction of the hook R, fig. 2.
N, four iron bars forming the grate.
DD’, aniron bar, fastened into the brick work at each
end, upon which the bars N slide.
* The day on which my memoir was received, I was informed
by Mr. Vauguelin, that Mr. Lebon, engineer of bridges and high-
ways, invertor of the thermolamps, had applied processes nearly
similar to mine to the carbonization of wood in his experiments. I
conceive therefore it is but justice to say with Mr. Vauquelin, that
nothing can be better contrived, than the apparatus of Mr. Lebon.
: L2 RAT K, the
140
Plate IV.
CARBONIZATION OF TURF.
K, the ash-hole, nearly in the form of a wedge placed
hhovicaneany:
Fig. 2. A,a, tubes to convey the gases from the ther-
molamp into the condenser.
E, e, keys to cut off the access of the external air to the
. eles while yet hot.
C, c, tubes to convey the gases that are not condensible
‘into the fire place.
F, f, condensers to be employed at iis F is a
‘stone hollowed out, and properly covered: f, a tub, or, if
it be preferred, a small cask.
S, 8S’, the pipe for the discharge of the distilled fluids.
Fig. 3. The carbonizing or thermolampic apparatus,
A, a, tubes issuing out of the furnace.
B, a crook to keep in its place the part opening at the
side, where the masonry forms a door closed with dry bricks,
removed and replaced at every operation.
C, body of the apparatus.
The dotted lines express the parts that are concealed, and’
are continuations of the lines drawn full.
Plate 1V. Fig. 4. Interior view of a fire place for burn-
ing turf, or turf charcoal. By this construction it appears,
that the disagreeable effects ascribed to the burning of turf
are avoided.
A, mantletree of the fire place.
B, a plate of metal, rising and falling in two lateral
grooves by means of the two copper buttons, C, C’.
E, the back, formed of a plate of cast iron, sloping at
the upper part. |
D, D’, the mantle-piece.
F, F, the sides, formingan angle of 135° with the bottom.
_ G, akind of box, consisting of two grates; the interior
one forming a pretty open angle with the bottom of the fire
place; the other, making the fore part of the box, and con-
sisting of two or three parallel bars. By this arrangement
the turf, which requires only a very rapid current of air te
burn it, is isolated.
H, the length of the bottom of the box, Somme like the
other part of common cast iron. es
) ; I, the
CURE FOR DAMP WALLS...... - 1A]
I, the ash-pit, the bottom of which is a little arched to.
ward the farther part, so as to give it greater depth.
K, K’, K”, the castors of the ash-pit.
Fig. 5. The profile or vertical section of the fire place.
A, the mantletree.
B, the anterior plate or regulator.
E, D, the posterior plate, of cast iron, curved so as to
leave an opening for the smoke four inches broad by sixteen
or at least fourteen long.
It must be observed, that this plate does not reach quite
to the top, and that the line is continued by loose bricks, to
facilitate the passage of the chimney sweeper; in addition
the interval E is filled with a mixture of powdered charcoal
‘and mortar or clay.
_G, shews the shape of the grate into which the turf or
charcoal is put.
Fig. 6. P, a pair of cranesbill tongs.
VI.
Method of curing Damp Walls, by the Application of a
Composition newly invented by Mr. Cuarres Witson,
of Worcester Street, near Union Hall, in the Borough.*
SIR,
. I BEG leave to lay before the Society of Arts, &c. a ‘Cement to
cement, which, I trust, will be found of great utility in a cas
curing damp walls, in flooring damp kitchens, and for va- floors,
rious other purposes, where the prevention of wet is ne-
cessary.
This cement when put in water will suffer neither an in- and join stone
crease nor diminution in its weight: and it has the peculiar °° ™"*
advantage of joining Portland stone, or marble, so as to R
make them as durable as they were prior to the fracture.
I have the honour to be,
Your very humble servant,
CHARLES WILSON.
* From the Transactions of the Society of Arts, who voted a
premium of ten guineas to the inventor.
Receipt
149 eYrEeCTS OF HEAT ON ANIWALS.
Reéeipt for making the Cement.
The cement. § Boil two quarts of tar with two ounces of kitchen
grease, for a quarter of an hour, in an iron pot. Add
some of this tar to a mixture of slaked lime, and powdered
glass, which have passed through a flour sieve, and been
dried completely over the fire in an iron pot, in the pro-
portion of two parts of lime, and one of glass, till the mix-
ture becomes of the consistence of thin plaster.
The cement must be used immediately after being mixed,
and therefore itis proper not to mix more of it at a time
than will coat one square foot of wall, since it quickly be-
comes too hard for use, and continues to increase its hard<
ness for three weeks. Great care must also be taken to
prevent any moisture from mixing with the cement.
For a wall which is merely damp, it will be sufficient to
lay on one coating of the cement, about one eighth of. an
inch thick ; but should the wall be more than damp, or wet,
it will be necessary to coat it a second time.
Plaster made of lime, hair, and plaster of Paris, may be
afterwards Jaid on the cement.
Mrs. Ann Kemmish, King Street, Borough; Mr. Boone,
Gregory Place; and Mr. Thomas Cannadine, Hook’s Gar-
dens, Tooley Street, have certified that Mr. Wilson’s ce«
ment has been used with effect, on damp walls belonging to
them.
VIL.
| Experiments on the Effects produced by a High Tempera-
ture on the Animal Econom, y By F. F. Detarocue, of:
Geneva.*
Living beings Aone the numerous characters that distinguish organ-
have a peculiar ized bodies, and particularly,those of animals, from inan-
“power of resist-
ing cold, imate substances, one of the most remarkable bey ond ques.
tion is the faculty they have of resisting cold, and preserv-
ing in general a temperature superior to that of the medium
in which they are placed. Accordingly this property of
* Journal de Physique, Vol. LXIIL. p. 207. Sept. 1806,»
living
EFFECTS OF HEAT ON ANIMALS. 143
living bodies has attracted the attention of physiologists in
all ages, who have mvented a thousand hypotheses, more
or less probable, to account for it.
It has not been the same with the faculty enjoyed by ani. and also. heat,
mals, and’ perhaps by plants likewise, of resisting heat,
and preserving a temperature inferior to that of the circum.
ambient medium. Scarcely any researches on this head were
made previous to the eighteenth century, when the inven-
tion of thermometers had enabled the philosopher to mea.
sure the heat of bodies with accuracy. The first experi-
ments that were attempted might have led us to doubt the
existence of such a faculty, Fahrenheit and Provoost, at First experi-
the suggestion of Boerhaave, exposed three animals in Pook oe ee
sugar baker’s oven, the temperature of which was 146° F. ee Killed
One of these animals was a dog weighing 101bs. one a cat, ince ns of
and the third a sparrow. All these died, the cat.at the ex- in 7 or 28 mi-
piration of seven minutes, the other two in twenty-eight. 2Uts-
These experiments were undertaken to verify a theory of poerhaave’s
Boerhaave’s respecting the use of respiration. He had sup- theory of respi-
posed, that it served, by the access of fresh air, to cool the a
lungs; in which, according to him, the blood underwent a
fermentation, that produced a very considerable degree of
heat. From the result of this experiment he thought him.
self authorized to conclude, that his theory was well found.
_ed, and that no animal could live exposed to a heat higher
than its own temperature.
The opinion of Boerhaave seems to have been pctoralt
adopted for a certain time by physiologists. It does notap- Temperature of
pear, that any precise notions of the temperature of hot ot climates.
climates were entertained at that time; but afterward more
' accurate ideas of it were formed, which did not agree with
the law established by Boerhaave. In 1748, Dr. John Li-
nings of Charlestown, giving an account of the meterolol
gical observations he had made in that place, noted the high
temperature observed there in summer. | Fahrenheit’s ther- 4¢ Charlestown
mometer in the shade frequently rose to 85° or 90°; and oe 908, and
once he saw it as high as 98°. ‘Though he did not examine si she sum
the temperature of places exposed to the sun, he estimated 124°.
with much probability, from other observations made in
lower temperatures, that it must have been 124°. Adan.
son,
144 EFFECTS OF HEAT ON ANIMALS.
son, in his account of his voyage to Senegal, makes some _
observations on the heat he had experienced in that country.
In Senegal, | Among other facts he relates, that, in an excursion he made
115% or 125°, in a small vessel on the Niger, the temperature of the cabin
in which he remained was from 115° to 125°, and did not
el night fall below 99° during the night. In 1758, Mr. Henry Ellis,
In Georgia governor of Georgia, communicated to the Royal Society
i. ase) jel fact respecing the excessive heat he experienced that year
thatiof the body at Savannah. The thermometer in an open room facing
only 97°. the north rose to 102°. Helikewise says, that going abroad
with an umbrella, to screen him from the sun, a thermome-
ter, which he held in his hand, rose to 105°: and that the
same thermometer, when applied to his eres: to his great
surprise fell to 97°.
Russian vapour Observations respecting the temperature of vapour baths
Teeete tase contributed likewise to shew, that man can support the ac-
~ tion of a temperature superior to that of his own body.
Such are those of Gmelin *, who observed, that the heat of
the Russian vapour baths rose.to 108°, and even 116° F,.
Some experiments on animals by Arnold Duntze+ afforded
Dogs supported Similar results with respect to them. Dogs confined in a
106° or 108%, stove were capable of supporting a temperature of 106°,
but killed
ee or even 108°, for a considerable time. It is true, ited.
ever, they died, when the heat was raised to 113° or up-
ward.
Animals.then Haller, in the second volume of his Klements of Physio.
support high Jogy, has collected these and other similar facts, from which.
temperatures,
and their bodies he concludes, that both men and animals, under certain cir-
= she cumstances, can support a temperature superior to that of
them. their own body; adding, that in one or two cases the per-
sons, who had observed this fact in themselves, had like-
wise remarked, that their own temperature kept itself be-
low that of the surrounding medium.
A girl could In 1760 Tillet and Duhamel had an nekosiasinaie af seeing
pan ry: at Rochefoucaut in Angoumois a baker’s maid-servant go
264°. into an oven, the temperature of which was at least 264°,
and stay there about twelve minutes, without much incon-
* Flora Sibirica, t. I. pref. p. 81.
+ Arnoldus Duntze, Experimenta C alorem Animalium spectan- et
tia, Leyden, 1754. Quoted by Haller.
venience. .
EFFECTS OF HEAT ON ANIMALS. 145
venience. After they were gone, a person who had been Another did the
present at this experiment repeated it several times at their ie sade,
request with another girl, employed in attending the same
oven, and the results were the same. It is to be observed,
that a spirit thermometer was used on this occasion, which
gave the temperature of the oven only by approximation.
Tillet considered the result of these experiments as militating Tillet’s remark.
“against that of Boerhaave’s. It appeared to him astonish.
ing, that animals should have been destroyed in so short a
time by a temperature of 146°, while women could support
a temperature of 264°: and he inferred, that the speedi-
ness of the death of those animals must be ascribed to some
cause foreign to the heat, such as the vitiation of the air in
which they were included. In consequence he made some
‘experiments, to ascertain how far Boerhaave’s opinion was
well founded ; who, in consequence of his theory of the
use of respiration, attributed the fatal effects of the heat to
its action on the lungs alone. He exposed some animals in Exposed ani-
an oven heated to 156° or 166°. First he put them in na- Bist) ee a
‘ked, and let them remain some time: then, having taken they bore,
them out, and allowed them time to recover themselves, he aiiaele de ia
wrapped them up in linen cloths, which covered the whole clothed.
of their body, and put them in again. In the latter state
they supported the heat much better than in the former.
Hence he coacluded, that the heat does not act on the or-
gans of repiration alone, but has a general effect on the
whole body. 3 |
Franklin, in a letter which he wrote to Dr. Linings, pub- Franklin ob-
_Jished in the Journal de Physique for 1773, after giving an pat dudyies
account of the researches he made in respect to the refri- than that of the
geration produced by the evaporation of fluids, endeavoured alts
to explain by this property a fact, which he had formerly
observed in himself. On a summer’s day, the temperature
of the air being 100°, he had remarked that his own tem-
perature was only 96°. He was at the time lightly clothed,
and in a profuse perspiration. The reason of this differ- and ascribed it
ence of temperature he imagined therefore, to be the eva.‘ ©v4poration.
poration going on from the surface of his body.
In 1775, Dr. Fordyce joined with Sir Joseph Banks, Sir Experiments
Charles Blagden, Dr. Solander, and some other natural phi- ape Hora yee,
losophers, —
146 EFFECTS OF HEAT ON ANIMALS.
losophers, to make fresh researches into the influence, that
high temperatures have on the animal economy. Their ex-
periments are too well known, to be repeated here: it is
Supported 2 Sufficient to say, that they could support for several minutes,
pe as without being too seriously inconvenienced, a heat superior
to that of boiling water ; and that they confirmed, in amore
accurate manner than had before been done, the faculty
man enjoys of keeping himself at a nearly constant tem-
perature, though placed in an atmosphere of which the
Ascribed itto heat is far superior to his own. These gentlemen, struck
Syaporations with the copious perspiration, that was formed when they
were exposed to the heat; observing too, that the moment
when this perspiration shewed itself was distinguished by a
diminution of the painful sensation they experienced from
the heat; were led to suppose, that the evaporation from
the surface of the body contributed greatly to this unifor-
which appeared Mity of temperature. Some experiments they made on the
emg heating of liquids exposed in open vessels, and intreduced
circumstances into the heated room, confirmed them in this opinion. In
from boiling. fact these liquids kept themselves uniformly at a temperature
below that of the surrounding medium, and could not be
brought to boil, till they were covered by a stratum of
They supposed Melted wax, which prevented the evaporation. Neverthe-
however some Jess these gentlemen did not think, that evaporation of the
Peete perspirable matter was the sole cause of the uniformity of
temperature, which they had observed in themselves, though
exposed to a heat so much higher.
Dr. Dobson At the same time Dr. Dobson, of Liverpool, made some
palit experiments in the hospital there, which were nearly similar
and attended with similar results.
J.Hunter ap» | About the same period too, ora little after, Mr. John
ae eee Hunter published some inquizies he had made respecting the
body, heat of animals. Most of these related to their faculty of
enduring cold; some however respected their capacity for
resisting heat. The latter were not made on the whole body
of men or animals subjected to the experiment, but on
atid iréagined particular parts merely; and Mr. Hunter thought he per-
its effects were ceived, that this faculty, though it could not he considered
resisted better 2
than those of 8 absolute, was more decidedly marked than that of re-
cold. sisting cold.
3 When
EFFECTS OF HEAT ON ANIMALS: \AZ
When Sir C. Blagden’s first paper appeared, Mr. Chan. Sik eae =
geux made some remarks on it.* He particularly endea- ai crapenaioh
voured to prove, that it was not by virtue of a particular
property, that the human body resisted the effects of heat,
but from causes purely physical. ‘These causes, according partly to the
to him, were on the one hand the evaporation of the per- onc ok
spirable matter ; on the other the ref rigeration of the air in- sage to the
troduced into the lungs, the effects of its rapid passage lungs.
through the trachea. He does not appear however, to have
made any experiment on the subject.
In 1779, Dr. Crawford, in the first edition of his work Dr. Crawford,
on animal heat, promulgated the opinion, that the faculty ppcetecses
possessed by animals of producing cold depended solely on from the skin
the evaporation of the perspirable matter pulmonary and phen
cutaneous. ‘Subsequently, in a paper in the Philosophical afterward in
Transactions, and in the second edition of his work, he ye pees oe
advanced a contrary opinion, founded on some experiments sorbed from the
of which I shall give an account in another place. is
Having observed, that animals exposed to heat vitiated
_ the air less by respiration than such as were exposcd to cold,
he thought he could explain by this fact the faculty of pro-
ducing cold which they possess. I shall not attempt here
to give an accouut of the theory he invented on this point,
a theory which I confess I do not very well understand.
- Such’are the principal researches and observations, that,
to the best of my knowledge, have been published respect-
ing the influence of heat on animals. ‘The subject how-
ever was far from exhausted, as several questions remained
undecided, and others even wholly neglected. A few in-
quiries, however incomplete, that I have made myself re.
specting it, will form the conclusion of this essay. They . \
are far from filling up the chasms that were left; but J shall — *
deem myself happy, if they throw some light-on a few
points, and meet the indulgence of the enlightened Judges,
to whom I submit them.
_ It is incumbent on me to add, that the experiments, which
constitute the base of these researches, are not exclusively
my own; they were made in concert with my friend, Dr.
* Journal de Physique, t. VII. p. 57 ;
ed Berger,
148 EFFECTS OF HEAT ON. ANIMALS.
Berger, of Geneva, who shared the labour, and assisted
me with his advice.
Sect. I. Of the Degree of Heat that Animals can endure.
The limits of It is scarcely possible to investigate the effects produced
ie bakes on animals by heat, and the faculty they have of resisting
with precision. it, without being prompted to ask, what are the limits of
this faculty? in other words, what is the greatest degree of
heat they can support, without being deprived of life ?—
This question however is insusceptible of a precise answer.
The time must The effects of heat being in the ratio of the duration as well
be consid: ed as intensity of its action, it is not till a very long time has
as well as the D . : :
intensity. expired, that we can consider an animal as having under-
gone all the influence of the heat to which it has been ex. —
Thetempera- posed, and conclude it to be capable of resisting it. We
babi ‘© cannot likewise prevent this temperature, on the one hand,
’ . . . . °
from experiencing considerable variations, which hinder its
and the animal being ascertained with precision; and the animal, on the
affected by va other, from being subjected to the influence of foreign cir-
Tious circum- 5 . .
stances. cumstances, by which the effects of the heat will be modi-
fied.
Gis castae The author here relates various experiments made ‘on se-
fiom the au- yeral animals, from which he draws the following conclu-
thor’s experi-
ments. sions.
From these experiments it follows, as might have been
presumed, that all animals are not equally affected by heat,
and that the faculty of resisting it is not the same in every
species. We cannot therefore derive from them any gene-
ral and precise conclusion with respect to the measure of
Small animals this faculty. These experiments however are sufficient to
sortie ae) shew, that most animals, at least those of a small size, sink
under a temperature of 144°, or even 134°, after a certain
space of time, which is generally pretty short. They shew
too, that the progress of the symptoms is more rapid, and
' the arrival of death more speedy, in proportion as the heat
is greater. | .
' The larger the The size of animals appears to have a marked influence
mre gg on the speediness of the effects of heat. The ass supported
heat. them much longer than the cat, the dog, the rabbit, and
the guinea-pig; and these longer than the mouse. The
magpie
«
INCREASE OF TEMPERATURE BY GALVANISM. 149
magpie and the bunting were killed sooner than the cock or
the pigeon. ‘The difference was scarcely less striking be-
tween a large and asmall frog, a beetle (scarabeus nasicor-
nis), and a wood-louse. It was not the same however in Exceptions,
all cases. The guinea-pig, though less, appeared to sup-
port heat a little better than a rabbit exposed to the same
temperature ; and the sparrow lived longer than the cock
and the pigeon.
The results were not less modified by difference of or- Cold blooded
ganization. Frogs and cold blooded animals supported aoe nana
heat much better in proportion to their size than hot blooded
animals. The larve of beetles, leeches, and fresh-water Other excep-
snails (budle fontinales ), though still smaller, supported it gm
_ equally well. It was not the same with beetles in their per.
fect state, mole-crickets, and wood-lice, which were killed
. much more quickly.
(To be continued.)
Vill.
On the Inorease of Temperature produced by the Galvanic
Action. By Mr. Joun Tatum, Jun.
To Mr. NICHOLSON.
Dear Sir,
In the paper I sent you about two or three months ago, Additional ex-
on the rise of the temperature of water during its decompo- Ber een
sition by galvanism, I proposed sending you the results of
other galvanic experiments I had made near a twelvemonth
since: but having mislaid the minutes I took during the ex.
periments, and various avocations preventing my repeating
these until the present time, is the cause of mynot fulfilling
my intention so soon as I wished.
In the following experiment 1 had two objects in view,
the one was, to ascertain the temperature to which the water
rose during its decomposition: the second, to confirm the —
faint recollection I had of muriatic acid being formedin the
experiment alluded to: for which purpose I made use of two
troughs, each 26 plates, each plate 50 inches surface; and
two
150 INCREASE OF TEMPERATURE BY GALVANISM.
two troughs, each 25 plates, each plate 36 inches surface ;
with diluted nitrous acid I had made use of four days be-
fore, now adding a little more acid.
Description of As the apparatus I made use of to contain the water is
the apparatus. one of my forming and making, it will perhaps be necessary
to describe it, before I relate the result of the experiment.
Let ABCD, Pl. IV. Fig. 7. represent a glass tube ca-
pable of containing 120z. of distilled water; EF a brass
cap, through which passes a screw G, to which can be at-
tached a platina or other wire; and by taking the screw out
another sort of wire may be fixed, as is represented by O:
H a box with leather through which the thermometer I
passes, and then screws on tight, graduated on the tube;
K-L a basin, in which the tube rests when filled with dis-
tilled water; M aneck, which may be fitted in any conve-
nient place to support the apparatus, screwing through the
basin, and terminating in a pair of forceps, into which may
be inserted any sort of wire.
On forming a connection at G with one end of the bat-
tery, and at M with the other end, the galvanic fluid will
pass through, and decompose the water in the tube; and
the thermometer will indicate the temperature.
Having explained the apparatus, I proceed to the expe-
riment.
The 2ink end of my battery communicated with G,
which was provided with a platina wire O. The inferior
platina wire P was connected with the copper end i the
battery.
Biscdiasiar A stream of gas was projected downwards half an inch
temperature from the lower end of the wire O. The wire P became
26 degrees. yided very fast; and the thermometer, which was at the
commencement of the experiment 54°, rose to 80°. When
I had decomposed 1ioz. of water, I disengaged the appa-
ratus, and tested the water (which was forced from the tube
into the basin) with the nitrate of wih which gave a white
appearance.
Miuriatic acid. From this appearance I conclude muriatic acid stilted: :
but what furnishes its constituent parts? surely neither the
glass tube, the platina wires, nor the basin. As we cannot
suppose that either of these furnished it, we must look for
its
INCREASE OF TEMPERATURE BY GALVANISM. 15]
its component parts in the distilled water, which is well
known to be composed of oxigen and hidrogen; and oxi-
gen being considered as the acidifying principle, I conceive,
that the muriate formed is an oxide of hidrogen, but in
such proportions as constitute an acid.
In hazarding this opinion I know I differ from, I believe
I may say, all of the most reputable modern chemists, such
as Thomson, Fourcroy, Accum, &c. who, when speaking
of acids, say * the base of muriatic acid unknown’; and
also, that ‘ oxigen forms no other combination with hidro-
gen, than that which constitutes water’. I hold these au.
thors in the highest respect, and derive the greatest infor-
mation from their works, which I conceive do them great
credit; but facts are stubborn things, and I make it a rule,
to bow my theory to truth. |
Lam, Dear Sir,
; Your most obedient,
JOHN TATUM, Jun.
April 14, 1807,
Dorset Street, Fleet Street.
P.S. At first I expected the mercury in the thermome-
ter to rise much higher, but, owing to using the diluted
acid a second time, the water was decomposed much slower
‘than in the experiment in my former paper; this, added to
the apparatus being considerably larger, much more metal
about the cap, and the thermometer having a largish bulb,
all. of which either absorb or conduct off the caloric, will
account for my disappointment.
SCIENTIFIC NEWS.
On the Tempest of Feb.. 18, which has produced many dreadful
accidents in the Channel.
(Continued from p. 88.)
N O one can read the detail of the numerous shipwrecks Observations
which are mentioned in letters from Havre, Dunkirk, Dieppe, >Y Marck
é 2 : i on his system
St. Valery, and Calais, without being deeply afflicted. Further concerning the
influence of the
details sai Laon, Bruges, ona, and Paris, augment the Von Geen the
melancholy weather.
152 SCIENTIFIC NEWS.
melancholy list of incidents. Surely, it 1s high time, that the
causes which produce such dreadful events were taken into see
rious consideration, and that an inquiry into them should re+
ceive the attention and interest to which it is entitled,
Paris, Feb. 25, 1807. LaMaRck.
The following letter from M. de Lalande to the editor of
the Moniteur has been inserted in that paper of the lst March
1807:
Remarks onthe Itdoes not appear in any wise probable to me, that the pass-
Sate ing of the moon through its nedes produces any sensible change
in the atmosphere, as M. De Lamarck thinks: but its passing
over the equator is more observable; I have noticed it many
times ; and even this year, in the months of January and Fe-
bruary, there have been alternations of cold and heat, which
appeared to follow the passings of the moon over the equator.
For that reason, I have marked them in the annuary of the
Board of Longitude, from the beginning.
But the dreadful hurricane of the 18th February can have
no relation to the moon. These phenomena proceed from the
winds, from thunder, and from volcanoes, orswellings of the sea.
We may hereafter learn, perhaps, that on the 18th February,
there have béen violent thunder storms in some of the southern
provinces, and I should wish to be informed of it through the
Moniteur, a paper in which scientific men like to deposit their
observations and remarks. :
(Signed) DE LALANDE.
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Nichotlsons Philos: Journal Vol: XVI, Pt:ill. p39.
Apparatus of M? Thillaye Platel,
for the larbonisation of Turf.
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Nicholsons Philos, Journal, Vol. 17. PV plé3
Theory of Looming or Horizontal Refraction.
A
JOURNAL
NATURAL PHILOSOPHY, CHEMISTRY,
a AND
oP haw: PEPE ARTS:
iis too: PUBY, TapK
ARTICLE I.
a es To Mr. NICHOLSON,
isi: SERS
IN orwrrustTanpinc the very ingenious inveftiga~ Looming, or
tions of Dr. Wollaston and othérs, it appears to me, that horizontal sae
the subject of looming, or horizontal refraction, is still ca- ‘unt
pable of being crulatied with greater precision, and upon
simpler principles: I shall therefore trouble you with a few fs
observations, which have occurred to me respecting it.
Let the refractive density of.a medium be supposed to Suppose strata
vary, eradually and equally, in parallel strata; the variation : tune wl
beginning, from a certain plane surface, and being conti- eee power.
nued, till, at a certain distance above that surface, the re-
fractive power wholly vanishes. For example, the re-
fractive density of air being expressed by 1.0003, if the tem-
perature vary 1° in 1 foot, the refractive power will vary
-000 000 6; and dividing 1.0003 by this, we have 1 666 667
feet, for the imaginary height of a mediam continuing to
vary at the same rate till its Mee datte power vanishes.
Now upon the projectile hypothesis, supposing a particle Progress of
of light. to be-initially at rest in this medium, it will be ac- light rs
tuated by a constant accelerating force; and by falling from
the top to the bottom, it will acquire the velocity natural
to light in the original medium: and if a ray of light enter
“Vou. XVIL.—Juxy continued, 1807. M the
154
Path of the ray
of light.
Apparent
place of the
object.
Double.
An inverted
object only.
LOOMING, OR HORIZONTAL REFRACTION. -
the variable strata from the medium, its motion will be simi<
lar to that of a jet or a projectile rising in any direction from
the bottom of a reservoir with the velocity due to its height.
Let A B (PV. Fig. 1.) be the imaginary height; if we de-
scribe the semicircle A C B,a ray of light entering,at B, in the
direction BC, will describe the parabolic path BD E, BE
bemg four times F C; or if the circle B GH be twice as
great in diameter as A B, F D will be equal to GI. And
if several rays, passing from a point K, (Fig. 2.) enter the
variable medium at the lower surface L M; making the se-
micircle K N equal to B GH, the distances KO, K P,-
will be equal to 2QL+42RS, and 2QT +2UX, re-
spectively. .
Now the distance K P must be a minimum, when the
fluxions of QT and U X are equal; that is, when KY
== XZ, (Fig. 3.) TY being perpendicular to K T, and
X Z parallel to KN. Make K 2 = K Q, and describe the
semicircles K 3, 28, Kg beg half of KN; draw K+
perpendicular, and + d parallel to KN; then JX, parallel}
to Q T, will determine the position of the point X fo as to
fulfil this condition. It is obvious that when K Q is very
small in proportion to KN, dX will coincide with Q T,
and X will be in the intersection of the circle K N with the
surface.
Consequently to an eye placed-at K, (Fig. 4.) the object
¢ will be seen in the direction K X, and the object 7 in the
directions K y and K 3; so that there will be two elevated
images of the line ¢ '& the one erect, and the other in-
verted. 3
If the variable medium be only thick enough to admit
the passage of the rays below KX, there will be no di-
rect image, but an inverted one only. The verted image
will in general be nearly of the natural dimensions, although
a little contracted ; the case being nearly similar to a very
oblique internal reflections The points K and < may be
considered as conjugate foci, with respect to the refraction
of the variable medium. .
In the supposed case of the variation of a degree for each
foot of air, K N beimg 34 million feet, if K Q be 1 inch,
KX will be 527 feet, and K ¢ 700 yards. The angular
deviation
LOOMING, OR HORIZONTAL REFRACTION. 155
deviation of the place of the point ¢ would be 32 seconds : Proportion of
the passage of the liyht through every 16 feet of the me- eho $59
dium producing a total deviation of a second; and if the-
change of the air’s density were more or less than <3, in the
space of a foot, the deviation would be as much more or less
than a second in each space of 19 feet through which the
light passes. The curvature of the earth's surface becomes
a second in 102 feet; consequently a change of density
2 ee y :
amounting to 5,45, m a foot, ora change of temperature of
a degree in 6 or 7 feet, would be sufficient to produce a re-
fraction equivalent to the apparent depression of a distant /
- object arising from this cause, and to elevate the coasts of a
wide channel, so as to make them visible to each other.
This result may also be more simply obtained from Simp-
son’s investigations respecting atmospheric refraction, the
refractive density being inversely proportional to the distance
from the centre of the earth, when the temperature varies
1° in 6 or 7 feet; for, as Dr. Young observes in his exten-
- sive system of. natural philosophy lately published, Vol, IT.
Art. 461, ‘* If the refractive density of a medium vary as a
given power of the distance from a certain central point, the
angular deviation of a ray of light will be, to the angle de-
scribed round the centre, as the exponent of the power to
unity.” ‘
Iam, Sir,
Your very obedient servant,
EMERITUS.
Postscript. If it be required to determine the position of Formula for
_& for the lowest ray that can cross the line € <, supposing sae
it to be at anv other distance from K, we must make the the image.
rectangle NU X=4N Ke; as may be understood by con-
sidering that the fluxion of the tangent of PK X is in-
versely as N U, and the fluxion of KU is as UX. This
determination requires in general the solution of a biquadra-
tic equation ; but when K ¢ is very small in proportion to
KN, U X will be very nearly + K ¢, or still more nearly
4Ke+Kecub. +64K Nq. The point ¢ thus found will
be the single point of the image as before: the length of the
_ -path of the ray within the variable medium will in both cases be
~ M2 : half
156
Formula,
Variation of
the medium
continued to
the eye and
the object
sometimes.
Object seen in
its true place.
LOOMING, OR HORIZONTAL REFRACTION.
half of the distance K ¢; but the total deviation of the light
will not be twice the angular displacement of the point ¢,
unless K and ¢ be equidistant from the surface. If however
the angular direction of the surface be known, as is almost
always the case in nature, the ancle P KX, which is half
the deviation, may also be found by observation ; being, for
example, when the surface is horizontal, the actual angular
elevation of the image of the pointe. The place of the
surface LM, which limits the variable medium, may be
found from the measures of the actual elevation and the
displacement of the point ¢; for its distance from’ 7, the
middle point between ¢ and its image, is always one fourth
of the elevation. .The circumstances will be nearly similar
when K is either in the line L M, ora little above it, pro- |
vided that ¢ be below it; but if both these points are above,
it, there will be no double image.
If however, the variation of the medium ia contmued, in»
an inferior degree only, to the place of the eye and the ob-
ject, effects of a similar nature may still be sometimes pro-
duced; but it is not sufficient in this case to suppose with
‘Dr. Wollaston, that the curve indicating the density has a
contrary curvature; for it must be such, that the change of
density, and consequently, the curvature of the ray, must
vary more rapidly than the distance from the line joining the
eye and the object; for example, if the curve be logarith-
mic, its subtangent must be considerably less than the great- —
est distance of the bent ray from: its chord ; otherwise there
can be no double image. Supposing the curvature of the
rays be as the distance from any given line, the form will. |
be nearly that of the harmonic. curve. But whenever the
object can be seen in its true place, beside the appearance
of one or more displaced images, it is obvious that both the
eye and the object must be sitiebadbk in a uniform medium,
as we have hitherto supposed.
II.
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M
PRUNING FIR-TREES. 157
s
Ik.
Pca on dag Fir.Trees; with an Engraving, to ex-
_ plain the Advantages of the Method recommended*, By
Mr. Rosurt SALMON, of Woburn, Bedfordshire.
Ot
SIR,
‘f HAVE the aie of transmitting to you some obser-
vations on the 1 management of fir eons. Having had
the ca re for some time past of such plantations,and knowing
how meh they are increased in this -Kingdom,, I considered pjantations of
it asa matter of importance, that a proper mode of manage- Fis much in-
ment, should be generally known, in order to bring timber sation
to the er eatest attaimable perfection. For this reason I have
tained my thoughts to the subject, and am confident that
much may be done, as is elsewhere asserted, by good ma-
nagement. I haye collected several specimens to demon-
strate the differ ence between good and bad management, and
have made some ‘obser vations, which [ have not before met
with, and niay perhaps be useful; you will have the good-
ness, therefore, to present these observations and specimens
to the Society of Arts, and to believe me,
E's f bit sat Your very humble serv ant,
Woburn, April 29, 1805. _ ROBERT SALMON,
_ To Dr. ¢ Cy T ayvior.
Fie
if
4
inte war
oe a
ii oad
Peeterentes to Plate VI. showing specimens of English grown
Fir Timber, cut out of his Grace the Duke of Bedford’s
© plantations at Woburn, pointing out the impropriety of
_ leaving timber to the course of nature, and the loss and Necessity of
defects that. arise from such mode of management ; also early and clore
illustrating the necessity of some finewan isl rule for PMNS:
managing ihe same, and the advantage of early and close
pruning off super fluous branches, with a general rule for
- * Transactions of Pebocety of Arts for 1806.
performing
158
3
Bough left too
long.
Other in-
stances of bad
pruning.
PRUNING FIR-TREES.
performing the same, and regulating the distance of the
plants in Fir Plantations.
Fig. 1. Section A. shows a dead knot and progress in the
growth of the tree, having 19 years of growth below the
bough, and 18 years above it. From the regular course of
nature, as shown by this section, it is evident, this bough or
knot must have existed as long as the upper part of the tree,
namely, 18 years. For the first three years the growth and
accumulation of the bough proceeded regularly with the
tree; but about that time (now 15 years ago) the bough
must have been distantly cut off, thereby preventing its re-
gular increase in the part left remaming; for 6 years after
cutting off it appears to have barely existed, and after that
ceased to exist at all but as a dead bough. Since it became
so, 9 years of accumulation have taken Cue on the trunk of
the tree, thereby gradually enclosing a part of the dead
bough, which part so enclosed is what by joiners 1s properly
called a dead knot; the boughs that exist and are enclosed
whilst living, are the live knots, and these the tree will pro-
duce either as the bough may be distant or close cut from
the tree. From this specimen may be determined, that if
the bough had been cut close to the tree at four years
growth, there would now have been sound clean wood over it
to the outside: or when it was-cut® if it had been taken off
at @, sound clean wood would have formed over it to the
outside,
N. B. In all the specimens this mark @ is affixed to point
out the proper place for cutting off, and is so placed as to
allow for thickness of bark at the time it should have ge
cut,
Section B. shows a striking imstance of the impropriety
of leaving the smallest Bogen cut at a distance from the
tree; this bough was cut off and became stagnant at 2
years growth, notwithstanding which it was 14 years before
the wood on the trunk accumulated to the end of the dead
knot.
Had this bough been cut at @, the knot as far as that
would have been firmly united with the tree, and above it all
sound clean wood.
Fig,..2.
\
PRUNING FIR-TREES. 159
Fig. 2. Section C. Another instance of improper cut- Bad pruning,
ting.
Ifit had been cut at @, the timber would have been more
valuable.
Section D. This before cutting exhibited a healthy bough,
and the section shows it the same, exhibiting a live knot.
This specimen clearly shows the progress of nature in healthy
boughs ; it also shows the great impropriety of suffering such
boughs to exist more than 5 or 6 years, at which age had it
been cut off, instead of a knot and great defect there would
have been clean wood from @ to the outside.
Fig. 3. Section E. Another striking proof of the impro-
priety of long cut boughs, a dead knot of many years stand-
ing, but far froin being enclosed now, admitting wet into the
heart of the tree: it should have been cut at @.
Fig. 4. Part of another Scotch fir.
- Section F. A very striking proof of young and bad prun-
ing. This bough was cut at 4 years growth, and now, after
18 years accumulation of the trunk, remaining uncovered,
and would so have remained many years longer.
Section G. A bough which, whilst standing, appeared not
vigorous or healthy; the section shows that at 6 years it was
im decline, and after that increased very little, though its in-
crease may be distinctly traced to the present time.
This should years ago have been cut off.
Fig. 5. A very complete specimen of good pruning, though Instance of
much too late. . good pruning.
Section H. A large bough cut off at 6 years growth, but
so close cut, that in 4 years afterwards the wood on the trunk
of the tree is arrived at the extremity of the knot.
Fig. 6. and 7. Parts of a Weymouth Pine Fir, 31 years Wood left to
growth, a mest striking specimen, and complete refutation itself,
to the doctrine of those who contend that the best way is to
leave plantations to prune themselves. This tree grew near
the outsidé of a thick plantation securely fenced, and ina
state of nature at the time it was felled, except some acci-
dental breaking off a few boughs near the bottom of the tree. m
- Before it was felled it indicated sickness by the foliage, but
from what cause it was so, no trace appeared, as the trunk
bore a very healthy appearance. The section shows, by the
small
160 PRUNING FIR-TREES.
small increase of wood for the last 6 years, that it was not
then healthy. ,
Section I. A dead knot’from a bough broke off at 6 years
growth; smce which 25 years growth of wood have for med
on the trunk, without nearly covering the stump ; this stump
was broken off before representation.
Fig. 7. is a horizontal section of three other knots cut from’
the same round as figure 6, showing the great obstruction to
the growth of the tree round the knots: this also explains the
cause of the great hollow round the knot in fig. 6.
The knot at K is a most striking and undeniable proof of.
the impropriety of leaving the smallest bough for nature’s
disposal.. ‘This bough protruded beyond the tree some dis-
tance, and evidently never existed but in a‘stagnant state,
for the last twenty-nine years; it being only two years old.
when it so became stagnant.
Fig. 8. A piece of the same tree as fig. 6 and 7; but from
the next higher tier of boughs, having a small piece wasted’
between the two.
Section L. Two small boughs, Whe upper one only one
year’s growth, was twenty years before covered, and has nine
years wood over it. The lower bough is of six years growth,
was twenty years before covered, a has four years wood |.
over it.
Perfection of | On contemplating these specimens; considering the pur-
Fir. poses that fir timber is generally applied to, and having some
knowledge of plantations of this sort, it must occur, that,
clearness of knots, straightness, length and equal size of its
trunk, constitute its perfection ; and, if deficient in all these,
it is of no value, but for the fire. Next to these considerations, ;
and the prospect of an improved knowledge of cultivating
-' this article, it may be a fair question, if our own country is.
not capable of producing fir timber little or not at all inferior.
to the foreign fir. ;
Fir may be _» At present firs in this country appear hot ne any siesta to»
produced here have been considered much otherways than as ornamental,
oe 2, For this purpose they serve but for a certain time, which
reign. past, it has been their fate to be cut down long before haying)
attained maturity. But from the vast plantations now esta-)
blished, it is,to be hoped, that another century may obtain,
to
:
PRUNING FIR-TREES, 161
to English Fir some. of the character of the English Oak 5
towar ds such end, if attainable, every means should be used,
aud towards it nothing appears more likely to succeed, than
a well grounded. general practical mode of management,
from the time of their being planted out, to their greatest
imaginable age of improvement. That a knowledge of such
may by perseverance be gained, is not much to be doubted;
and by imspecting and considering the specimens herein re-
ferred, to, there ¢ appears great reason to conclude, that early
gud proper pruning “and thinning. will form a considerable
feature in the system to be adopted.
Now as forms are first instruments in good systems, and
- as proceedings on fundamental principles (though in the
essay they may a little err) are better, in a general view, than
occasional success by hazard; so it may be warrantable that
a system for general management may be laid down, al-
though the author cannot possibly have lived to prove all by
experience : so the rules hereafter submitted are given, being
the result of only a few years observations.
For planting, from every authority or observation, there Planting thick.
can be no doubt that all firs should be planted thick; not
more than four or five feet apart.
Where firs of the same kind are planted together, there is Not several
less loss of plants from one sort overgrowing mn destroying ner toge-
the others ; consequently it appears per stan ep that all the '°"
different sorts be: planted by themselves. If any admixture
be at all admitted, the Scotch and larch may best succeed :
but this is not certain, and they will certainly be best sepa-
rate on two accounts; first, because they are not so likely to
injure each other; and secondly, the larch may be put ito
the ground best suited, to them, and the Scotch the same.
In making plantations of any particular sort, it may, be Spruce as a
right to foe a few spruce, or other sorts onthe outside, to skreen.
prevent. mischief from sudden gusts of wind; but if the si-
tuation is not subject to such gusts, the spruce had better be
. omitted, being mechanical agents only, and by excluding
the sun and air they act against the operation of nature.
In these hints ornament is not, considered; if such be Omamental
wanted, and profit also, then the spruce, larch, silver, and P/@™tons:
some others may be combined.
From
162
Rules for
pruning.
Thinning,
PRUNING FIR-TREES.
From some years observations on pruning and the effects
thereof, it appears certain, that Fir trees, at a certain age,
shouid be pruned to a certain height; and for regulating
thereof, the following simple rule is recommended. The
pruning to commence when the trees are six years old, or
when there is discernible five tiers of boughs and the shoot ;
the three lower tiers of boughs are then to be taken off.
After this first pruning, the trees to be let alone for four or
five years, and then, and at every succeeding four or five
years, the pruning to be repeated, till the stem of the tree
is clear to forty feet high, after which, as to pruning, it may
be left to nature. The rule for the height of pruning, after
the first time, to be half the extreme height of the tree, till
they attain twenty years growth; and after that time, half
the height of the tree, aud as many feet more as it is inches
in diameter at four feet from the ground. ‘This pruning is
known from repeated observations not to be excessive; and
the rule is calculated to check the too tapering top, and
strengthen the slender bottom, by carrying the pruning to
a greater proportionate degree, in a ratio compounded of
the height and bottom bulk; and by this rule it may be ob-
served, that the trees wil! be at top clothed with somewhat
Tess than half their branches. The proper time for pruning
is between September and April, and the tool to be used, the
saw.
Orderly thinning the trees at certain periods is the next
essential to pruning, and for this purpose observations have
been made on the most orderly aud thriving plantations, and
the following simple rule is recommended. Keep the dis-
tance of the trees from each other equal to one fifth of their
height. In the application of this rule for thinning, it is
evident, that each individual tree can never be made to com-
ply ; for the original distance (even if planted in the most
regular order) will allow only of certain modifications, by
taking out every other tree, and so on ; but even if the ob-
taining such equal distance was practicable, experience would
show that another way should be preferred, of which the eye
must be the judge, by taking out such trees as are least
thriving, stand nearest another good tree, &c.; at the
same time keeping in view the rules prescribed : the follow~
ing
PRUNING FIR-TREES.
ing of which rules may easily be proved by measuring a chain
square, or any quantity of the land, and counting the trees
thereon ; then by trying the height of two or three trees in
that quarter, and taking one fifth of such for the distance,
it would be readily seen how many trees should be contained
in'the piece measured: or the practice may more simply be
regulated, by taking the distance of eight or ten trees added
together, the average of which should be equal to a fifth of
the height of the trees.
In these rules nothing impracticable or complicated is pro-
posed.
The author has for years known the expense and produce
from trimming only, and fiuds in Bediordshire the produce
doubly repays the expense; and although some experimen-
talists' may differ from him, or time may show some reason
for deviating somewhat from his rule, yet it is presumed all
will‘agree that some simple system is adviseable, instead of
having plantations and woods mismanaged, to the great loss
of the’ community and the proprietors. If such a system as
proposed be generally promulgated ; if not perfect, it will
most likely, in time, become so, and thereby have its ad-
vantage; and that some advantage may be had in specula-
tion, the following concluding remarks are introduced.
163
Produce of
trimming
more than
pays expense.
In the common course of gardening, it is understood, Pruning gar-
that pruning invigorates the tree; that trimming off the side
branches makes the upright oues shoot the strouger, and by
cutting out the dead and decayed wood the tree is kept
alive: some of this doctrine will certainly apply to the tribe
of firs; it will certainly substitute clean wood for knots, and
of all this treatment, from their particular uses, they of all
other trees stand in most need, and will be most improved
den trees.
by it., And should it be admitted, that like treatment would Advantage of
on the firy:as ‘well as other trees, produce the like effect, i
would lead to a well-grounded expectation, that, as well as
producing clearness from knots, straightness, and length, the
same operation would advance the quality nearer to that of
foreign fir; for it may be traced, that where trees are tall
and clear of boughs-or knots, the whole substance of the
wood is better and of finer grain, and it appears likely, that
such will always be the case: the reaso: may probably be
é inferred
t pruning Firs,
164 ; “ATTRACTION AND REPULSION
inferred from the sap haying farther to rise and. descend;
and having no boughs to divert or delay it, the civeulation
must be mote fine and rapid, most increase be left. in, the
neighbourhood of the boughs at the top of the tree, and
least on the sides,at the lower’ part; consequently adding to
the length of the head, and rendering more fine each annual
increase to the body ; thereby producing a close-grained,
clean, long, and regular, easy-tapering, useful piece of tim-
ber; instead of a coarse-grained, short, sudden-tapering
|
|
|
|
|
trunk, with a quantity of boughs and knots.
Appieabloute The foregoing observations and rules are meant to apply
ether timber. to. fir.timber only, but to a certain degree they may. be ap-
plied to other timber} though by no, means ,to the same, ex+
tent, orage. But if applied as far as the first fourteen years
of their growth, and. then the pruning altogether .omittedj
and the thinning-out very much increased, any. plantation
would be rendered much more valuable, than if left epbinely
to nature.
ROBERT SALMON, ctaeae ss
Woburn, April 2, 18006;
TH.
Abstract of a Memoir read at the Meeting of the fifth, Class
of the Institute, September the 29th, 1806, by Mr. ae
PLACE, on the apparent Attraction and Repulsion of small
Bodtes Jloating on the Surface ft Laquids™.
a :
t 334
Bodies Hottuie I N the theory L have given of capillary attraction) Thave
on fluids at- subjected to analysis the attraction of two vertical and) pa+
ee ae rallel planes, very near each other, with their lower -extre=
mities immersed in a fluid. I have shown, that, if they be
when they are of the same matter, this action tends to bring them meéarer
of the same together; whether the planes elevate the fluid near. them,
raise as-ivory immersed in water; or depress it, as laminar. tale,
on which we feel a. kind of unctuosity, that. prevents tliem
* Journal de Physique, Vol. LXUI. p. 248,
from
:
OF SMALL FLOATING BODIES.
from being wetted. Bach plane is then pressed toward the
_ Other plané by a force equal to the weight of a parallelopipe-
don of the fluid, the height of which is half the sum of the
_ elevations above the lev el, or depressions below it, of the ex-
| treme points of contact of the interior and exterior surfaces
of the fluid with ‘the plane ; ; and the base of which is that
part of ‘the plane included between the two horizontal lines
drawn through those pomts. "This theorem includes the true
cause of the apparent attraction’ of bodies swimming on a
fluid; when it is elevated or depressed ‘around them. But
experience shows, that: bodies repel each other, when the
- fluid risés toward one of them, and is depressed toward the
other... Having applied my analysis to these repulsions, it
has ld me to the following results, which T conceive may be
deemed interesting by the natural’ philosopher and geome-
trician, «and complete the theory of capillary attraction:
ct we’ still suppose the bodies to be vertical and parallel
planes, the section of the surface of the fluid included be-
» tween them by another vertical plane perpendicular to these
will have a point of inflexion,; when the two planes are a
few centimetres [a centimetre is near four lines English]
from each other. | [f they be brought nearer together, the
point of inflexion will approach nearer to that plane, toward
which the fluid is depressed; if the depression of the fluid in
‘contact with the exterior side of that plane be less than the ele-
‘vation of the fluid in contact with the exterior side of the other
plane.’ If the contrary be the case, the point of inflexion will
approach the other plane. This point is always in the level of
_ the fluid in the vessel, in which the planes are immersed. The
“elevation and depression of the fluid in contact with, these
_ planes’ are less’at the interior surface than at the exterior.
In this state the planes repel each other. On continuing to
bring them nearer, the repulsion still subsists, as long as
there is'a point of inflexion. This peint at length coincides
“with one of the planes, |The repulsion still continues be-
yond this period; bat on continuing to bring the planes
_mearer together, the repulsion becomes null,-and is con-
“verted into attraction? At this instant the fluid is equally
elevated on each side of the plane that is capable of being
wetted ; and it is as much elevated ubove the level at the
interior
165
Force of this
attraction,
But they are
repelled, ifone
eleyate the
fluid, the other
depress dite
i.
Theory.
Circumstances
under which
the repulsion
takes place.,
At length an-
nihilated, and
becomes at-
traction, when
the ae is
equally elevat-
ed on each side
of one plane,
and as much
depressed on
one side of
the other.
166
Case of con-
stant repulsion
The equation
of the curve of
the surface not
obtainable in
finite terms,
except within
a certain dis-
tance,
Modified by
friction.
When thesur-
face is wetted
it attracts at a
greater dis-
tance.
ATTRACTION AND. REPULSION
interior of the other plane, as it is depressed below it at the
exterior. ‘Thus the repulsion is changed into attraction at
the same moment in each plane. On bringing them still
nearer, they attract each other, and proceed to unite with
an accelerated motion. These planes,therefore exhibit. the
remarkable phenomenon of an attvaction at very small dis-
tances, that is changed into repulsion beyond certain limits ;
a phenomenon which nature presents likewise in the iuflexion
of light near the surfaces of bodies, and in the attractions
of electricity and magnetism.. There is one case, however,
in which the planes repel each other, however small»their
distance may be; and this isswhere the fluid. is depressed |
near one of them as much as it is raised near the other.. Here’
the surface of the fluid has. constantly an inflexion in the
middle of the interval between them. r
The integration of the differential equation of this susface
in general depends on the rectification of conic sections, and
consequently it is impossible to obtain it in finite terms,
But it becomes possible, when the planes are at the distance —
where repulsion is changed into attraction ; as this distance
can then be determined in a function of the elevation and
depression of the fluid at the exterior of the planes. . Thus
we find, that it is infinite, if the depression of the fluid on-
the exterior of the plane incapable of being wetted, be infi-
nitely small: whence it follows, that the two planes never
repel each other then. This may take place too even in the
case where the fluid is perceptibly depressed at the exterior
' of the latter plane: as it is suMficient, if friction keep the
fluid a little more elevated at the interior of the plane, than
it would be if this friction did not exist; an effect analogous
to that daily perceived in the barometer, when the quicksil-
ver 1s falling. We find too by this analysis, that, if the sur-
face of the plane capable of bemg wetted come to be made
wet, the two planes will begin to attract each other at a very
perceptible distance, greater than that at which they began
to attract each other before. | It is net the truth. therefore
to say, that two planes, one capable of bemg wetted, the
other not, always repel each other. The same thing happens
here as with two balls having the same kind of electricity,. a3
these attract each other notwithstanding, when we vary in a
suitable
OF SMALL FLOATING BODIES. 167
suitable manner the respective intensities of their electricity,
and their distance.
By means of the two following theorems, we may calcu- Calculation of
late the tendency of the planes toward each other, or their Sede
mutual repulsion,
Whatever be the substances of which the planes are form- Theorem I.
ed, the tendency of each of them toward the other, is equal
to the weight of a parallelopipedon of the fluid, the height
of which is the elevation of the extreme points of contact of .
the fluid with the interior plane, minus the exterior eleva-
tions the depth half the sum of these elevations; and the
breadth that of the plane in a horizontal direction. We
must consider the elevation as a negative quantity, when it
is Changed into depression below the level. If the product
of the three preceding dimensions Prete negative, the ten-
dency become repulsive. ’
When the-planes are very near together, the elevation of Theorem Ul.
the fluid between them is the inverse ratio of their mutual
distance ; and is equal to half the sum of the elevations, that
would haye taken place, if we suppose the first plane to be
of the same substance as the second, and then the second
plane to be of the same substance as the first. We must ob-
serve too, that the elevation must be put as riegative, when
it changes into depression.
We see by these theorems, that in general the repulsive The repulsion
force is much weaker than the attractive, which displays itself Spe ieee
when the planes are brought very close together, and must
then carry them toward each other with an accelerated mo-
tion. In this case the elevation of the fluid between the
planes is very great, relatively to its elevation near the same
planes exteriorly. If therefore we neglect the square of the
latter elevation, with respect to the square of the former,
the fluid parallelopipedon, the weight of which expresses the
tendency of one of the planes toward the other, in yirtue of
the first of the preceding theorems, will be equal to the
product of the square of the elevation of the interior fluid,
by half the breadth of the plane in the horizontal direction.
This elevation being, by the second theorem, reciprocal to
the mutual distance of the planes; the parallelopipedon will
; ofa Te
168 ATTRACTION AND REPULSION, &c.
be proportional to. the horizontal breadth of the plane di-
Follows the vided by the square of this distance. The tendency of the
pallor lair two planes toward’ each other, therefore, will follow the ge-
raction. : ? 2 5c
neral law of attraction, that is to say, it will be in the in-
verse ratio of the square of the distance.
Put to the test -° Desirous of kriowing how far these results of my theory
ofexperiment, Pore agreeable to nature, I requested Mr. Haiiy to make
some experiments on this delicate and curious point in na-
and found to. tural philosophy. » Te complied with my wishes, and found
beagreeable the formule in perfect unison with experience. “He parti-
ae cularly ascertained the singular phenomenon of an attraction
‘changed to:repulsion By thes increase of distance, as the fol-
ieivchad note I received from hin ‘will show. :
Abbe Hays 2% I sdioeth aka a small square leaf of laminar talc to 4 very
experiments slender thread, i such a manner, that its lower part was
on thesubject. + omersed in water, In the same water, at the distance of 2
few centimetres, I immerséd the lower part of an ivory pa-
yallélopipedon, ‘so that one of its faces was parallel to the
leaf of tale. I then caused the parallelopipedon to advance
very slowly toward the leaf of talc, keepmeg it still in a pa-
rallel position, and stopping at intervals, to be certain
thé motion, that might be imparted to the fluid, did not
sensibly affect the experiment.’ The leaf of tale then re-
ceded from the paralleloptpedon ;* and when, on continuing
"to ‘move the latter with extrerne slowness, there remained but
avery small distance between the two bodies, the leaf of talc
suddenly approached the parallelopipedon, and came into
contact with it. I then separated the two bodies, and found
the parallelopipedon wetted toa certain height above the le-
vel of the water; and on repeating the experiment, without
wiping it, the attraction began sooner; sometimes indeed
it took place from the first, without being preceded by any
perceptible repulsion, These experiments, carefully re-
peated several times, always afforded the same results,”
gta ver Cary.
ADHESION OF BODIES TO FLUIDS, 169
i
Abstract of a Memoir on the Adhesion of Bodies to the Sur-
Jace of Fluids, read at the Sitting of the first Class of the
Institute, November the 24th, 1806. By Mr. Laruacr*.
A GREAT number of experiments have been made on Dr. Young first
the adhesion of bodies to the surface of fluids, but without accounted for
any suspicion, that this adhesion was the effect of capillary pelos aig
action. Dr. T. Young appears to me to be the first, who surfaces of flu-
made this ingenious remark ¢. On applying my analysis to ‘pa ies “ng
his experiments, I have found, that it represents them as
well as could be expected with regard to experiments so very
delicate, and not always agreeing exactly with each other.
~The phenomena of capillary action being now reduced to a Theory of ca
mathematical theory ; nothing more is wanting to this inte- P”9 i, papi
refting branch of uatural philosophy, but a series of accu= ly experi-
rate experiments, in which every thing capable of affecting ™°"'*
‘the result of this aétion is carefully removed. The want of
very precise experiments is felt, in proportion as the sciences
advance toward perfection. To the concurrence of the great Cause of the
discoveries in mechanics and mathematics with those of the eta
telescope and pendulum, astronomy is indebted for its vast
progress. We cannot therefore too strongly invite the phi-
losopher to give the greatest precision to his operations; as
we cannot sufficiently encourage the skilful artist, who de-
votes his labours to the improvement of the inftruments of
science. A single experiment badly executed, has frequently Necessity of
been the cause of many mistakes; while an experiment well Fy ras,
performed subsists for ever, and sometimes becomes a source
of discovery. On such an experiment we rely with confi-
dence; but the cautious inquirer feels himself under the
necessity of verifying the results given by an observer, who
has not acquired a solid reputation for accuracy.
* Journal de Physique, Vol. LXIII. p. 413. Nov. 1806,
+ Vhilosophical Transactions for 1805: or Journal, Vol. XIV. p. 74, .
158.
VoL. XVII.—JvuLy continued, 1807. N When
170
Glass on the
surface of wa-
ter resists sapa=
ration with a
force propor-
tional to its
size.
Cause of this.
Vase where the
fluid would
sink in a capil-
lary tube,
ADHESION OF BODIES TO FLUIDS.
When a disk of glass is applied to thé surface of water
standing at rest in a vessel of considerable extent, on endea-
vouring to separate it from the water we find a resistance
proportional to the surface of the glass, On rdising the
glass, we raise at the same time a column of water above
the level of the surface, which resembles in its figure the
grooved wheel of a pulley. Its base extends indefinitely on
the surface of the level : as the column proceeds upward it
diminishes to about seven tenths of its height: above this it
enlarges, till its summit covers the surface of the disk, To
determine its volume, let us conceive in the plane of its
least diameter an interior canal, at first horizontal, after-
ward curved vertically as far as the level surface-of the fluid,
and at that point resuming its horizontal direction. It is
easy to perceive, that, in the case of the column being in
equilibrium, the power owing to the capillariness of its sur-
face must balance the weight of the fluid in the vertical
branch of the canal. On raising the disk higher, the weight
becomes more powerful from the capillary attraction, and
the column separates from the disk. The weight of the co-
luma of water raised m this state of equilibrium is the mea-
sure therefore of the resistance experienced in separating
the disk. If the breadth of the disk be considerable, we
find by analysis, that this weight is equal to that of a cy-
linder of water, the base of whichis equal to that of the
disk, and the height the product of one millimetre [0°391
of a line] multiplied by the square root of the number of
millimetres in the height to which water would rise in a tube
of glass one millimetre in diameter. The surface of the
water is a tangent to that of the disk; but if these two sur-
faces cut each other, the preceding result must be multiplied
by the cosine of half the acute angle formed between them,
and divided by the square root of the cosine of the entire
anele,
When the fluid, instead of rising, would be depressed in
a capillary tube of ‘the same materials as the disk, as mer-
cury ‘is in a tube of glass, the column raised by the disk
has no longer the shape of a pulley: its base extends inde-
finitely on the surface of the fluid, but the column decreases
continually from this base, till it comes into contact with the
disk,
ADHESION OF BODIES TO FLUIDS.
disk. The weight of this column, in a state of equili-
brium, 1s equal to that of a fluid cylinder, the base of which
is the surface of the disk, and the altitude the product of
one millimetre, multiplied by the number of millimetres the
fluid would sink in a tube of the same material as the disk,
and of one millimetre in diameter, this product being mul-
' tiplied by the line of half the acute angle that the surface
of the fluid forms with the disk, and divided by the square
root of the cosine of the whole angle.
All these results require a slight correction, relative to the
supposition of a great diameter of the disk. I shall give
this correction, which may be neglected without any sensi-
ble error for disks the diameter of which is thirty millime-
tres [11°74 lines] and upward.
To compare the preceding results with experiment, let us
consider a disk of glass 100 millimetres [3 in. 9 1.] in diame-
ter. Mr. Haiiy has observed, that in a tube of glass one
millimetre in diameter, water would rise 13.569 millimetres
above the level: whence it is easy to conclude, by means of
the theorem above given, that the force necessary to sepa-
rate the disk from the surface of water would be equal to a
weight of 28-931 grammes [446819 grs.]. Now according
to Mr. Achard this force is 29°319 grammes [452°832 grs.],
which differs very little from the preceding result. I made
some experiments on the resistance opposed by a disk of
glass applied to the surface of mercury. But to compare
them with the theory, it is necessary to know the angle
formed by the surface of this fluid in contact with the glass.
An experiment of this kind, made with precision, is well
adapted to determine this angle, which appears to be of 30°
or 40°.
171
The theory
compared with
experiment.
~ If we place two disks of glass horizontally on each other, Two disks of
leaving between them a very thin stratum of water, these glass with a
stratum of
- two disks will adhere with considerable force. Tc determine water between
this force, it must be observed, that the interposed fluid
then takes the form of a pulley; and that the smallest ra-
dius of curvature of its surface is very nearly equal to half
the thickness of the stratum. Neglecting here then, as may
be done when the disks are very large, the greatest radius of
curvature, we find the resistance, that the two cylinders op-
ty pose
them,
172 ADHESION OF BODIES TO FLUIDS.
pose to their separation, equal to the weight of a cylinder of
water, the base of which is the surface of the disk, and its
altitude the height to which water would rise between two
parallel planes of glass, as distant from each other as the
aba Si interval that separates the disks. Mr. Guyton de Morveau
much greater made an experiment of this kind with two disks of glass, the
ais mp, diameter of which was 81°21 millimetres [3°18 inches], and.
theory, he found their resistance to separation 250°6 grammes
{3870°5 grs.]. According to the preceding theorem, the re-
sistance would be only 155°78 grammes [2406 grs.J. The
from mistak- difference of about one third between these two results,
ing their dis- : : : :
tance, arose, no doubt, either from the estimation of the. interval
that separates the disks, which requires great nicety in such
or inequalities small intervals; or to the equalities of the surfaces of the
of their surface. disks, which it is difficult te render accurately plane.
Wieory 6 The sustentation of small bodies on the surface of fluids
small bodies. depends on thts general prmeiple: “ The diminution ef
oo on weight of a body merging in a fluid, that sinks around it
by capillary action, is the weight of a volume of fluid equal
to that of the part of the body beneath the level, added to
the weight of the volume of fluid displaced by capillary ac-
tion. If this action raise the fluid above the level, the di-
minution ef weight of the hody is the weight of a volume
of the fluid equal to the part of the body below the level,
minus the weight of the fluid raised by capillary attrac.
tion.” :
Diminution of . Lhis prmeciple embraces the known hydrostatical prin-
weight of bo- ciple of the diminution of weight of a body plunging
ies in Auids. ito a fluid: it is sufficient to omit what relates to capillary
action, which totally disappears, when the body is com-~
pletely in the fluid below the level of its surface.
Demonstia- To demonstrate the principle just laid down, let us sup-
ia oe pose a vertical tube large enough to include the body itself,
and all the body of fluid that it sensibly raises, or the space.
it leaves empty by capillary action. Let us conceive this
tube, after having penetrated into the fluid,.to bend hor
zontally, and afterward rise vertically, preserving the same
~diameter throughout its whole extent. It is clear, that, in
the case of an equilibrium, the weights in the two vertical
branches of the tube must be equal. The weight of the
body
ADHESION OF BODIES TO FLUIDS, de
body therefore must compensate the vacuum it produces by
capillary action; or, if it raise the fluid by this action, its
inferior specific gravity must compensate the weight of the
fiuid raised. in the first case this action raises the body,
which by this means may be retained on the surface, though
specifically heavier than the fluid: in the second case it has
a tendency to sink the body in the fluid. It is thus that a Steel floating
very slender cylinder of steel, the contact of which with ° Water.
water is prevented either by a varnish, or a thin stratum of
air surrounding it, 1s supported on the surface of the fluid.
If we place thus two equal and parallel cylinders, touching Two equal
each other, but the extremity of one passing beyond that eee tee oe
of the other, we perceive them immediately sliding by each contact, will
other to bring their extremities on a level. The reason of tigation’
this phenomenon is visible. The fluid is more depressed by their whole
the capillary action.of the two cylinders at that extremity of 78th.
each which is in contact with the cther cylinder, than at the
opposite extremity. The base of the latter extremity there-
fore experiences greater pressure than the other base, since
the fluid around it is more elevated. Consequently each cy-
linder tends to unite with the other more and more: and as
the accelerating forces always carry a system of bodies, the
equilibrium ef which is deranged, beyond the state of equi-
libration ; the two cylinders must alternately pass each other,
producing an oscillation, which, diminishing incessantly, by
the resistance the cylinders experience, will at length be an-
nihilated. The cylinders, being thus arrived at a state of
rest, will have their extremities parallel. These oscillations
may be determined by analysis, and we may compare the
theory of capillary action on this poimt with experiment.
These comparisons are the true touchstone of theories, which path ronta
leave nothing to be wished, when by means of them we can Seaside,
not only foresee all the effects that must result from given
circumstances, but determine their quantities with accu-
racy.
if we consider the whole of the phenomena of capillary Capillary at-
action, and their dependance on one single principle of an pas a = :
attraction between the molecules of bodies decreasing in a 2 eer =
very rapid ratio, it is impossible to call this principle in culesofbodies,
question, This attraction is the cause of chemical affinities : which is the
' ++ cause of che-
# micalaffinities,
1.74: ADHESION OF BODIES TO FLUIDS.
it does not stop at the surface of bodies, but, penetrating
into them to depths which, though imperceptible to our
and accounts S€4Ses, are very sensible in the action of affinities, it produces
for the influe that influence of masses, the effects of which have been dis-
eg ger played by Mr. Berthollet in such a happy and novel man-
ner. Combined with the figure of capillary spaces, it gives
rise to au almost infinite variety of phenomena, which, like
those of the celestial bodies, are now brought within the do-
Allies chemis- mains of analysis. Their theory is the most imtimate point
Caer PPY- of contact between chemistry and natural philosophy ; two
sciences, which now approach each other on so many sides,
that one cannot be cultiyated with much success, without a
thorough knowledge of the other.
Capillary at- = The resemblance of the figure of fluids raised, depressed,
traction pro- : 4 A 5
duces a cate- oF rounded by capillary action, with the surfaces generated
nary curve, by the curves known under the name of catenary, lintear,
and elastic, on which mathematicians employed themselves
at the origin of the infinitesimal calculus, led some _philo-
but the sur- sophers to suppose, that the surfaces of fluids had a uni-
Aa bills pice form tension, like elastic surfaces. Segner, who appears to
form tension. have been the first that suggested this idea*, was well aware,
that it could be no more than a fiction, adapted to represent
the effects of an attraction between the molecules decreasing
with great rapidity. This able mathematician endeavoured
to demonstrate, that this attraction must have the same re-
snits: but, if we examine his reasoning, it is easy to per-
ceive its inaccuracy; and we may conclude from the note
appended to his researches, that he seems not to have been
satisfied with it himself. Other philosophers, resuming the
idea of a uniform tension of fluid surfaces, have applied it
to various capillary phenomena. But they have not been
more successful than Segner, in the explanation of this force ;
and the most able have contented themselves with consider-
eer ee ba ing it as a means of representing the phenomena. Tn giving
truths, into all the conjectures, which may arise from the first view
of these phenomena, we may hit on same trutiis; but they
will almost always be mingled with many errours, and the
but he is the discovery of them belongs only to him, who, separating
discoverer who
observes or in- * Mem. cf the Royal Society of Gottingen, Vol. I.
them
LOOM WORKED BY STEAM OR WATER. 175
them from this mixture, goes fo far as to eftablifh them on V*tigates
: 2 . : . them with ace
folid foundations by obfervation or mathematical invef= curacy,
tigation.
V. °
Account of a Loom to be worked by Steam or Water ;* by Mr.
j Joun AustTIN, of Glasgow,
SIR,
Ar TER much trouble, expense, and reiterated experi-
ments, I have happily succeeded in completing a new WEAV- New looom for
1nG-Loom, a Working-Model of which, with cloth in it, is weaving.
presented to the Society for their inspection. it has, upon
trial, succeeded beyond expectation, answers in every respect
the purpose for which it is intended, and has met with the
approbation of manufacturers of the first respectability in the
country.
After many different attempts, I think that I have brought worked by
my weaving-loom, which may be driven by water, or steam, water or steam
to such a state of perfection, as to prove its utility, the more
it is known and employed. attempted
, long ago, and
My first attempt was made in the year 1789: Tat that Qaiiedinto ex:
time entered a caveat for a patent, but relinquished the idea ecution.
of obtaining one, and have since made many improvements
‘upon my original plan. In 1796, a report in its iavour was
made by the Chamber of Commerce and Manufactures at
Glasgow ; and in the year 1798, a loom was actually set at
work, at Mr. J. Monteith’s spinning-works, at Poliockshaws,
four miles from Glasgow, which answered the purpose so well,
that a building was erected by Mr. Monteith, for containing
thirty looms, and afterwards another to hold about two
hundred.
‘The model now submitted for inspection is an improvement
upon those constructed for Mr. Monteith.
* Transactions of the Society of Arts, 1806. The gold medal of the
Society was voted tv Mr. AusTIn for this invention,
The
176
Enumeration
LOOM WORKED BY STEAM OR WATER.
The following are the advantages which my ‘com pos-
of its advanta- sesses,
ges.
1. That from 300 to 400 of these looms may be worked
by one water-wheel, or steam-engine, all of which will weave
cloth, superior to what is done in the common way.
2. That they will go at the rate of sixty shoots in a mi-
nute, or two yards ofa nine hundred web in an hour.
3. That they will keep regular time in working, stop and
_ begin again, as quick as a stop watch.
4. They will keep constantly going, except at the time of
shifting two shuttles, when the weft on the pirns is done.
5. In general, no knots need to be ‘tied, and never more
than one, in place of two, which are requisite, in the common
way, when a thread breaks.
6. Incase the shuttle stops in the shed, the lay will not
come forward, and the loom will instantly stop working.
7. They will weave proportionally slower, or quicker, ac-
cording to the breadth and quality of the web, which may be
the broadest now made.
8. They may be mounted with a harness, or spot heddles,
to weave*any pattern, twilled, striped, &c.
9. There is but one close shed, the same in both breadths,
and the strain of the working has no effect on the yarn behind
the rods,
10. The bore and oe always keep the same proper
distance.
11. There is no time lost in looming, or okie out the
cloth; but it is done while the loom is working, after the first
time. |
12. The weft is well-stretched, and exactly even to the
fabric required,
13. Every piece of cloth is measured to a straw’s breadth,
and marked where to be cut, at any given length.
14. The loom will work backwards, in case any acci-
dent, or of one or more shoots missing.
15. Every thread is as regular on the yarn beam as in the .
cloth, having no more than two threads in the runner.
16. Ifa thread should appear too coarse or fine in the web,
it can be changed, or any stripe altered at-pleasure.
17.
LOOM WORKED BY STEAM OR WATER. ,
A7. They will weave the finest yarn, more tenderly, and
‘regularly, than any weaver can do with his hands and feet.
18. When a thread either of warp or weft breaks in it,
the loom will instantly stop, without stopping any other loom,
and will give warning by the ringing of a bell.
19. A loom of this kind cccupies only the same space as
a common loom; the expense of it will be about half more;
but this additional expense is more than compensated by the
various additional machinery, employed for preparing the
yarn for the common loom, and which my loom renders en-
tirely unnecessary.
20. The reeling, winding, warping, beaming, looming,
combing, dressing, fanning, greasing, drawing bores, shifting
heddles, rods, and temples, which is nearly one half of the
weaver’s work, together with the general waste accompanying
them, which is about six per cent of the value of the yarn,
and all which occur in the operations of the common loom,
do not happen with my loom, which, by its single motion,
without further trousle, performs every operation after the
spiuning, till the making of the cloth is accomplished; by
which, independent of the saving of the waste, the expense in-
curred for reeling, warping, winding, &c. is saved, amount-
ing to above twenty per cent of the yarn.
21. The heddles, reed, and brushes, will wear longer than
usual, from the regularity of their motion.
22. More than one half of workmanship will be saved:
one weaver and a boy being quite sufficient to manage five
looms of coarse work, and three or four in fine work.
These advantages, which from experience my weaving-loonr
has been found to possess, and which upon inspection will be
perceived, will, I presume, be esteemed of some magnitude.
My loom, as now constructed and improved, is much sim-
plified, so that the manual labour requisite is trifling; and if
it is encouraged by the Society of Arts, I am sensible much
advantage will arise from their approbation, and the publicity
it will in consequence receive.
| Tam, Sir,
Your humble servant,
JOHN AUSTIN.
Certificates
177
178
Certificates of
its utility.
Copying ma-
chine,
COPIES OF WRITTEN PAPER BY PRESSURE.
‘Certificates were produced from Messrs. Hue Cross,
Mattuew Prrsren, and Davip Murrieg, dated Glasgow,
October 12, 1796, stating that, by appointment of the Cham-
ber of Commerce in Glasgow, they had inspected the Loom,
constructed by Mr. Austin, and were of opinion, that it will
be found to contain some ingenious and useful improvements,
by producing saving and facility in several of the ordinary
operations.
Messrs. Nerz, Macvicar, and Toomas HenpeErSON, of
Edinburgh, certified on the 12th of April, 1804, that they had
seen, in the Trustees office there, the model of Mr. Austin’s
Loom, and that they thought it ingenious, and the best they
had then seen.
Further Certificate, from Edinburgh, dated April 14, 1804,
from Mr. Jounn Drummonp, and from Messrs. James
Rerp and Joun WavueGu, partners in the house of WALTER
BicGer and Co. linen-manufacturers, testify to the ingenuity
of Mr. Austin’s Loom, and that it is capable of being employed
to the great advantage of the manufactures of this country.
Mr. Austin having left a complete Working-Model of his
Loom with the Society of Arts, &c. a reference to it will con-
vey an idea of its principles, better than any description that
might be attempted ; as from the variety of minute parts in it,
the Committee of the Society have thought it impossible to
have a drawing of it, upon their usual scale, which can be ren-
dered sufficiently intelligible.
Vie
»
Observations and Experiments respecting the Art of making
Copies of Written Paper by Pressure. By R.T.
SIR,
A Few years ago, a Machine, called a Copying Machine,
was offered to the Public for the purpose. of obtaining a copy
from any recently written paper.
To merchants and others, who are in the habit of writing a
great number of letters, &c, of which they wish to have a
copy
COPIES OF WRITTEN PAPER BY PRESSURE. 179
copy, this invention bas been of so great utility, that it has
now come into very general use.
The method of using this instrument, which is a rolling Method of
press, is briefly this: Having covered the paper to be copied ™sing it.
with a piece of damp copying paper (a kind of white, thin,
unsized paper, made on purpose), place it between oiled pa-
pers ona board, cover it with some blotting paper, and pass
it through the press: a copy, which is legible through the
copying paper, is thus obtained from writing that has been
- written only a few hours. Thus far this machine fully an-
swers the purpose; but when old writing is made to undergo Does not an-
this process, no effect is produced. Pacee old
Should any method be discovered of obtaining copies from i
old writing, it would prove a valuable acquisition to many
persons, and to mein particular. It is with the view of obtain-
ing information on this subject, that I have troubled you with
this letter; you, or some of your correspondents will, 1 hope, tpformation ow
through the medium of your valuable Journal, favour the this head de-
public with some communication, that may throw a light on mani:
this interesting subject.
The following account of a few experiments I have made
will, perhaps, be of service in forming a judgment as to the
means most likely to succeed; or they may be useful to any
one, who may chvose to prosecute the matter experimentally.
I remain, Sir, | |
Your obedient servant,
To Mr. NICHOLSON, ae
—_——
4 first tried the most violent pressure (both with and with-
out the substances hereafter mentioned), without advantage.
A moderate pressure is best. Writing can seldom be got out anaes
after it has been written more than 24 hours,
In taking off writing, a considerable improvement was dis-
covered ; it consists in covering the copying paper with flannel
instead of oiled paper. By glueing the copying paper on.a
piece of white paper, the writing is rendered more legible,
Notwithstanding these, and using boiling water instead of
cold, the old writing continued refractory.
Experiments.
Mechanical
180 COPIES OF WRITTEN PAPER BY PRESSURE.
Solutions ap= Mechanical means having failed, it was necessary to en-
re rape crease the power by the assistance of chemistry.
copying paper With this intent, I soaked either the old writing or the co-
pying paper in various solutions, and passed them through
the press. Old writing is rendered blacker by being soaked
Infuston of for some hours in infusion of galls, but it bas no power to bring
ma it on to the copying paper.
Green vitriol, | Solution of sulphat of iron produced no effect.
Praisivetave With triple ake of potash a faint copy was Sometimes
ash, obtained ; often it had no effect: a few drops of sulphuric
acid added to it increased its power, but the whole was ren-
dered green.
Hidrosulphuret of ammonia has more powerful action on
writing than any thing I have yet tried. When this liquid is
Fe hestvhve pee on faded or almost any kind be eid? it eee it
ret of anmo- io an intense black colour. By the aid of this preparation,
nia. T have been enabled sometimes to procure tolerably good
copies, but could not obtain a constant effect, though I often
varied the progress. -
But the action of hidrosulphuret of ammonia is incom-
plete, the black it gives to writing is not permanent, and on
some writing it has no effect.
As this substance appeared more likely to succeed than any
other, I was induced to examine it more particularly, but the
result has convinced me its power is inadequate to the
purpose. |
The reason it gives a black colour to writing is this : almost
all inks contain an excess of sulphate of iron; the ammonia
combines with the acid, and the sulphuretted hidrogen With
the iron, forming the black colour; and because different
inks contain different proportions of sulphate of iron, they will
not be equally affected by the hidrosulphuret of ammonia.
LCR, The hidrosulphuret of iron is mi ole by the carbonic
tet of iron de- acid of the atmosphere.
coniposed by
the air. :
The following experiments will prove these positions. Write
; on paper with;
No. 1. A solution of tan.
No. 2. A solution of green sulphate of iron.
COPIES OF WRITTEN PAPER BY PRESSURE. ist
No. 3. A pale ink formed with green* sulphate of iron
and solution of tan, having excess of sulphate.
No. 4. An ink as above with excess of tan.
Pour on the writings hidrosulphuret of ammonia; Nos,
1 and 4 will remain unchanged, Nos. 2 and $3 will instantly
become intensely black, but No. 2 changes by exposure to a
rusty brown, and No. 3 becomes faint.
If hidrosulphuret of ammonia is poured into solution of sul-
phate of iron, a black powder precipitates; when this is ex-
posed to the air it turns toa red rust.
Although the hidrosulphuret appears to have no effect on
dry tannate of iron, yet when poured into the ink No. 4, it
changes it toa red colour; writing written with this mixture
becomes nearly black inan hour. When filtered, a red sub-
stance remains, and the filtered liquor is of the same colour.
I have somewhere seen it asserted, that ink consists of a b duiststinnty
black powder suspended in water, so extremely fine as to pass ablack powder
with the liquor through a paper filter; this is not exactly Suspended in
water,
the case.
If ink, prepared as No. 3, be exposed to the air a short time
-and filtered, a black mass remains on the filter, and the li-
quor that passes through is of a fine deep blue colour: if a
drop be let fall from the filter on a piece of ivory, and exa-
mined immediately, it will appear a homogeneous liquor, but
in the course of a minute numerous black particles will
be seen floating in it.
These effects are best perceived with a glass. Some of the
filtered ink placed ina wine glass is speedily covered with a
film; on shaking the glass, black pieces will be seen in the
apparently colourless liquid, that trickles down the sides.
From this it is evident, that new ink consists of at least two 4 .jubte blue
substances, one soluble in water, and communicating to it a and insoluble
3 black sub-
dark blue colour, the otheran insoluble black powder. uaees
* This was the green vitriel of commerce boiled on iron filings to de-
prive it of any excess of acid, and to bring it toa minimum of oxigen ;
but Ido not know whether it was exactly in that state. The ink is of a
blue colour, and passes through the filter without leaving scarce any resi-
duum: the writing written with it is at first excessively pale, but gradu-
ally becomes black. i
182
both probably
tannates of
iron,
Ink not well
understood.
Queries res-
pecting its na-
tare.
Water not the
only men-
struum ofdyes.
OF VIOLET PURPLE DYES.
It is highly probable, that these are tannates of iron, differ-
ing merely in the proportion of oxigen which they contain,
especially as the blue is changed into the black by exposure
to the air.
The nature of ink is ‘at present not well understood ; but it
is not my intention to undertake its investigation, I leave that
task to an abler hand. I beg leave, Sir, to conclude, by pro-
posing a few queries for your consideration, and for that of
your correspondents.
In what do new aud old writings differ ?
Is the difference in consequence of the particles of the old
writing having become more firmly united together by time;
or is iton account of their having undergone some chemical
change®? If the latter, in what does this change consist?.
Tsit the tannate ofiron, which has suffered an alteration? or
is it the gum, which all inks contain?
Is it there any substance capable of dissolving, without de-
composition, the black tannate of iront?
ERE ENLIST ET
VAE.
Of Violet Purple, and the different Tints that may be derived
from it; by Joux Micnaut Haussmayf.
'W arer is not the sole menstruum capable of extracting
the colouring parts of plants, in order to enable them to ad-
here to alumine or oxide of iron fixed in any cloth. ‘There
are vegetables, as alkanct root, which give out their colouring
* That it isnot on account of a chemical action having taken place
between the tan and the gelatine of the paper, will appear from this, that
unsized paper yields a copy no easier than any other.
+ From the experiments of Bouillon Lagrange, which render it pro-
bable, that strictly there isno such thing as gallic acid, and from the
manner in which ink is generally prepared, viz. by long boiling, which _
must dissipate the acid if it exist, I have been induced to omit taking i¢
into account.
t Annales de Chimie, vol. Ix. p, 288, December, 1806.
matter
es tek
OF VIOLET PURPLE DYES. 183
matter only to alcohol. I shall not attempt to define the na-
ture of the colouring matter of alkanet: it is so readily de-
composed by the continued action of heat, even below the fs colour de.
temperature of boiling water, that, after it has been extracted composed ata
by alcohol,,it cannot be concentrated by evaporation without nee
being destroyed; so that it is impossible to make any farther
use of the spiritous part of the tincture of alkanet, as I have
convinced myself, by reducing a certain quantity to one
fourth by distillation. The alcohol that came over appeared
to me perfectly pure; and the residuum was muddy, and un-
fit for dyeing. I confess I was to blame for not having exa-
mined it more thoroughly, to see whether it contained any
thing oily or resinous; but I had then no other object in
view, than to avail mysclf of the colouring properties of alka-
net, with which I had reason to be satisfied. ;
On mixing a sufficient quantity of spirituous tincture of Tincture of
alkanet with six or eight parts of pure water in a copper a eae eae
boiler; and afterward dyeing in it hanks of cotton prepared water. f
for Adrianople red, according to my process inserted in the gy. cotton,
Annals de Chimie, year 10, by Mr. CHarrat, at that time prepared for
Minister of the Home Department; at the expiration of an S¢anerle
P ? | red,
hour, raising the fire gradually till the bath was brought to boil,
they were of a fine violet purple colour.'To produce this colour
constantly of the greatest brightness, the cotton must not be
made dull by the preliminary preparations, and consequently
must not be galled. The linsed oil [ employed for the prepa-
ration was boiled with ceruse, taking care not to burn it, that
it might not soil the cotton.
The great lustre of this violet purple on cotton, which sur- of alustre sua
passes that of the finest satin dyed in the common manner, ie! to that
soe i of satin,
a fine purple,
suggested to me the idea of producing it in fine printed goods.
My expectations were so far answered with success, that we
presently manufactured some whole pieces of long shawls,
with a ground of this colour, for Mr. Soehné, Sen. and Co. of
Paris, who received them a few years ago, and admired them
very much. They found the price, however, too high for the yee we
times. Formerly, when it was common for ladies of fashion pensive tor the
to wear printed calicoes both in summer and winter, it was PTsem! tines.
necessary for those who would force a business to have arti-
cles
184 OF VIOLET PURPLE DYES.
cles of this kind of very high price. I had proofs of this two
fn 1775, rich and thirty years ago, when I lived at Rouen; for having then
prints sold at 5 few sown pieces of ten ells, of a very rich pattern, to sell on
Rouen for 5 2 y p ?
£1 13 6 a commission, I disposed of them without difficulty at two and
yard. thirty louis a piece. These articles were from the manufac-
Mr.von Schule tory of the illustrious John Henry von Schule, of Augsburg,
pune lc age who is well and justly entitled to be styled illustrious, as the
printed goods first manufacturer in Europe, who carried the printing of
ui Europe. — calicoes to great perfection and extreme beauty. His arti-
cles have made so much noise in all parts of the mercantile
world, that the emperor of China desired to see them, and
admired them in comparison with the productions of his own
dominions.
_ Cottons intended to be printed with violet purple grounds,
Cottons must 22d to have any white figures, require to be very well
be well bleached, that they may be muddied as little as possible in
bleaghed: dyeing: for, though the violet purple is such a fixed colour,
as to support the action of the alcaline lixivium of oxigenized
munriate of potash,without being much weakened, the white is
restored but slowly.
Alumine fixed in the cloth, and saturated with the colour-
eee ing particles of tincture of alkanet, will still admit the colour-
upon the alka- ng matter of other vegetable or animal substances; which
mar aie week gives rise to an infinite number of other tints, that may be in-
j creased indefinitely, by more or less diluting the acetate of
alumine employed in the printmg; and by dipping the violet
purples, and their derivative tints, thus produced, in a bath
of madder, cochineal, kermes, brazil, weld, quercitron, &c.
By mixing these drugs in different proportions, the tints may
be greatly increased in number; and still farther by mixing
more or less acetate of iron with the concentrated or diluted
solution of acetate of alumine.
Cotton printed with oxide of iron, or a concentrated solution
chant ia of acetate of iron, takes a greenish black from the tincture of
alkanet: and by diluting the solution of acetate of iron in
different proportions, we shall obtain a great variety of grays,
more or less deep, and more or less green. These tints are
equally susceptible of variation by means of the dyeing drugs
Other colours #/7eady mentioned. ;
printed by the If we wish to produce other colours by the: side of the
side of ite ground
;
-
hi
se
&
4
3
colouring drugs, or the acetate of iron.
ON CAST IRON. 185
ground of purple violet, or its derivative tints, without per-
ceptibly altering this ground, it is necessary, before the
blocks with other mordants are applied, to pass the alkanet
ground through dilute sulphuric acid, to carry off the alu-
mine, that has been left untouched by the colouring parti-
cles of the alkanet. The purple and its derivative tints will
be reddened a little indeed by the action of the acid, without
however being much weakened.
Linen prepared in the same manner as cotton presents
nearly the same colours and tints when dyed with tincture y+ an may be
of alkanet ; and admits the same variations by means of other dyed with al-
kanet,
The same may be said of silk properly alumed. It affords and silk,
very brilliant colours by being passed through tincture of ~
alkanet ; which however only gives the silk a muddy tinge,
‘if it be prepared with a solution of tin of any kind, instead but not with
of being alumed. This shows the little affinity of the “07 o™
- oxide of tin for the colourimg particles of alkanet, which
produce no better effect on linen or cotton, prepared with so-
lutions of the salts of tin.
__ 'The same inconvenience would probably take place with
wool, which I have not treated with tincture of alkanet: but
no doubt it would exhibit nearly the same colours as cotton,
linen, or silk, after having been well alumed.
Woollen.
~
Vill.
On Cast Iron; by PRroressor Provust.*
(GFRAY' ana black cast iron afford an aromatic hidrogen,
‘which appears to me to hold in solution a part of the oil that apes hi-
‘is formed during their solution in acids. This hidrogen iat cecal
burns heavily; and its flame is tinged with yellow and green. cast iron,
“Four mches of this gas, however, burned with eight of
‘oxigen, consumed only two, or no more than pure hidrogen
‘would have done. The residuum did not render lime-water
“turbid. I suspected, therefore, that the oily particles might:
PBs .
a * Journal de Phisique, vol Ixiii..p, 463, December, 1806,
Vou. XVII.—JuLy, 1807. O have
186 ON CAST IRON.
have escaped combustion; but we must not forget, that very
small quantities of carbonate of lime are soluble in lime-water.
Sia eh ana ~ Six inches of this gas, and sixteen of oxigenized muriatic
16 of oxigeniz- gas were reduced im the space of an hour to ‘halves inch, the
ed muriatic - syeater part of which was still oxigenized muriatic gas. A cloud
gas reduced by : Se :
mixture to:» Was formed at the instant of mixture, anda light greasy pel-
_ Greasy pellicle licle flodted on the surface of the water, but I was not able to
formed. examine it. This gas likewise contains phesphorus. Phos-
Contains phos- phorus, in fact, must occur in cast iron oftener than is ima-
phorus. gined ; for I have perceived a phosphate in almost all the
solutions of our Spanish cast iron. But beside the ore there
Phosphate in are some kinds of charcoal that coutribute to this. That of
the ashes of
the quercus ) the evergreen oak, for instance, must contain’ either phos-
ilex. phorus or a phosphate, since the latter is found in its
ashes. |
Their Plumbago.
Carbon sepa- The carbon separated from cast iron has the leaden ap-
rated from cast... att: : aed oy ,
ai tapiear pearance, lustre, and scaly texture of plumbago ; particularly
likeplumbago. when it has been thoroughly freed from iron by the muriatic
Is plumbago acid: but is plumbago in fact a combination of iron with
acarburet? — Gaybon, a metallic carburet, as it has been considered ever
since the time of Scheele? His own experiments, in con-
junction with some particular facts, lead ine to doubt this; _
and I am at present fully persuaded, that, before we give im-
plicit credit to this combination, it would be proper to sub-
ject it to a fresh examination.
Supercarburetted Cast Tron.
Cast iron over- [ had occasion to examine some cast iron that had been
bi a ae refined according to Grignon’s principles, or by keeping ita
fusion, long time in fusion. The cannons made of it were proved
by dic corps of artillery under the reign of Charles II, and
would not stand the trials. —
This iron, when broken, had not the granulous appear-
ied eee ance of gray cast iron; it exhibited to the eyea heap of small
needly cones, very obtuse, between which micaceous scales of
plumbago were visible when inspected with a lens, The
superabundance of this facilitated the crystallization. Under
the hamimer it is compressed, and crumbles, The file cuts
it
*
’
.
ON CAST IRON. 187
it very easily. A skilful workman succeeded in forging a
piece without melting it, and formed a plate of it, which, af-
ter tempering, appeared to be very steely. Hence I conceive
it follows, that, if cast iron gain in metallization by continu-
ing the heat, it loses by the diminution of its oxide a princi-
ple, that seems indispensable to the solidity of its texture.’
‘If this oxide, which segves the purpose of interlacing the Tough cast
metallized parts, and of preserving a more complete conti- oye Ansa
guity between them, happen to be deficient, the liquidity of iron in the
the fused mass cannot avoid being diminished, and its place metal,
must be supplied by carbon, to keep up this effect. But
when the iron owes it liquidity to this new principle, it is far
from having the same coherence or tenacity as in the former
case. Whatever may be thought of this opinion by those
metallurgists, who are engaged in casting artillery, I conceive
it will be of use to them, to preserve the history of these facts.
But if we continue for the present to consider-the carburet If a carburet,
of iron as an actual combination, we must allow, that its’ex- Still Pues 4
_ istence, or its solution in cast iron, affords us an example of a ee eat)
combination, a compound with the excess of one of its ele- f one of its
. : : : . , elements.
ments, or, if you please, of another kind of union, to which
Mr. Berthollet does not appear to me to give a full assent.
I have examined cast iron obtained with the pit-coal of As- Cast iron im-
turia in furnaces, that had neither the height, nor strength of eid pit
blast, commonly required to reduce iron ore by this combus- coal.
tible. This cast iron, on coming out of the crucible, boiled ;
till it began to fix. The result was white, blistered masses,
fit for nothing but making cannon balls. It was easy to see,
that this ebullition was nothing but a continuation of the ef-
fervescence, which had not terminated in the furnace.
Its solution confirmed this opinion, for it afforded infinitely 4 gorded less
less hidrogen than white cast iron. hidrogen.
The labours of Bergman, Berthollet, and many other sci- @, 5, ; on re-
entific men, confirmed by the methods practised in England, tains oxide in
to promote the disoxidation of the parts in which this process solution,
has not taken place, scarcely admit of a doubt, that cast iron
is nothing but metallic iron serving as a menstruum to a por-
tion of its oxide. But are not such solutions so many exam-
ples of compounds dissolved in an excess of one or other of
their elements?
Og - Sulphurate
iss.
Analogous in-
stances.
Copper.
Silver.
Superphos-
phurretted car-
bon.
Amalgams.
Water.
Hidrogen.
Hidrurets.
Various com-
pound solu-
tions in che-
mistry.
ON CAST IRON:
~
Sulphurate of copper dissolves in copper, one of its elements.
The black coppers contain it, and even sulphurate of iron and
suphurate of silver likewise. We may presume from these
instauces, therefore, that there would be nothing extraordis
nary in finding sulphurets, phosphurets, and carburets, dis-
solved in their respective metals ; and consequently, to see
these metals dissolve other oxides. Af cast iron be an instance
of this, that of the oxide of copper in its metal is another, for
which we are indebted to Mr.Chenevix ; and the experiment
of Fernandez on the solution of muriate of silver in its metal
is a third.
~Phosphuret of carbon is a compound, that dissolves in
phosphorus, one of its elements, im we know not what pro-
portions,
_ Amalgams are compounds, some of which appear to bie
proportional, and others not. Some separate from the exeess
of mercury, and afford means of studying them: others re-
main in complete'solution in it in progressive quantities, the _
extent of which is not known.
Water is a compound, which by the assistance of circum-
stances dissolyes in oxigen gas, and in hidrogen gas, or in
either of its elements.
Hidrogen is anelement of fat oils, volatile oils, camphor,
&c.; but we find, that, during their passage in vapour through
a red hot gun-barrel, hidrogen can disengage itself from ihe
coal, and dissolve a part of these vapeours.
Nothing surely can be objected to our disses Pe an
extension of these principles, solutions of sulphur, phospho-
rus, carbon, arsenic, zine, &c. in hidrogen, not as simple
solutions without any measure, but as so many compounds
in ‘due proportion, as so many hidrurets of sulphur, phos-
phorus, &¢e. which an excess of the solverit may hold in
solution. - ;
If we cast our eye over the whole field of chemical science,
we shall discover there too a multitude of compounds, -
which dissolve others; some in proportions that are ‘easily
estimated by a separation of the excess ;-and others, that, not
yielding to this method, continue to fluetuate in the-e¢ean of
indeterminate quantities: so that even at 'the present hour
we are ignorant, whether we ought to place m the’same “tne
the
“4
, ON CAST TRON. 189
the compounds that are confined to constant proportions, and
those that are subject to none, though both are the result of
the same power. aie :
Mr. Berthollet, in his Third Series oftaguiries concerning
Affinities, expresses himself thus:
“«< Proust asserts, that compounds, the proportions of which Objection of
are fixed, may unite with an excess of one of their elenrents Pollet.
inan indefinite proportion ; without defining the characters,
that distinguish combination from this other-kind of union.
It is obvious, that, in consequence of the latter distinction, it
would be difficult to object to him any observation, which he
would not find means to explain.”
-. ifthe preceding faets, to which many others might be pyoust’s an-
added, since the works of the elder chymists are loaded with swer.
_ them, sufficiently prove the existence of these kinds of union,
or solutions of compounds by their elements, or even by other
compounds; it would appearto me superfluous to insist longer
upon them: but I have been able to make them concur in
the explanation of certain phenomena, without any contra-
_diction of principles. As to the characters that distinguish
them, or ally them to those compounds that range under the
laws of proportion, I am entirely of Mr, Bertholiet’s opinion.
But how should I define those characters? All the elements
of such unious are not sufficiently known. Chemistry not
having yet called for-their being subjected to a particular
study, it is enough for the present to exhibit them as incon-
testable facts, till reflection determines their proper place in
the edifice of science. -
-
Hidrate of Iron.
Mr. William Talaker, our collector for the Cabinet of A fne yellow
Madrid, found a very fis yellow ochre in the mountains of Beds mee
_Artana, in the kingdom of Valentia: It contains a little carbonate of
‘carbonate of lead, though there isno mine of that metal in lead.
the neighbourhood. This was taken up by weak nitric acid,
without altering the colour of the mineral.
This ochre, freed from lead and carefully dried, was sub- 6, distillation
jected to distillation in a retort of ten inches capacity. The gave out 12 of
aqueous vapour that arose completely expetied the air from 4"
‘the retort, and with it about half-an inch of carbonic acid
eon gas
o
190 FILTERING STONE.
~
gas. A hundred parts of the ochre freed from lead were
reduced to eighty-eight of a —_ fine red powder. The
product was pure water.
“Muriatic acid = Muriatic acid applied to the residuum, separated forty-
separated "44 four parts of sand: consequently there were forty-four parts
of sand. : : .
of red oxide likewise, :
Hidrate of read ‘Lf forty-four parts of this oxide were combined with twelve
oxide. of water, one’ hundred parts must have been united with
twenty-seven in this oxide. It was therefore a hidrate, with
base of red oxide.
If the red oxide, which is generally less disposed to enter’
into combination, be capable of producing a hidrate, must.
~ not the black oxide be mucli more so? The hidrate.of iron
then with base of oxide at a mmimum will be found some
Hidrate of — day, either pure, or in a compound of this metal. I am of
canbe ae opinion it is in this state, that it makes a part of the car-_
carbonate of f i pllee ibe
iron, bonate of iron, the base of which is always at a mmimuin.
-
TX.
On Filtering Stones, and the Method of determining the spe-
cific Gravity of Substances with large Pores. By Mr.
Guyton*,
\
Filtering Boru Linneus and Wallerius have spoken ofa filtering
cP TC sandstone: cos filtrum particulis arenaceis equalibus, aquam -
ceous, transmiltendo stillans: cos particulis arenaceis puris aquam
transmiittens. On their authority most mineralogists have
classed these stones among the varieties of arenaceous quartz:
but we do not find, that they had ascertained whether the
silex in them were pure, or merely the predominant princi--
ple. The former appears however to be the most general
Kirwan men- 9pinion, since, excepting one passage in Kirwan, where he
Pe cliciennn mentions the pierre de liais among the silicicalcareous stones
as porous, and used for filtcrind: ft, we do not find in the
‘
* Annales de Chimie, Vol. LX, p 121. Nov. 1806.
+ Elements of Mineralogy, Vol. I. p. 102, 7
most
FILTERING STONE, 191
most modern works on mineralogy any mention of-that kind
of stone, which is so much used at Paris for filtering water,
and the advantages of which have been confirmed by an ex-
perience of more than thirty years.
This is a yellowish free stone, of a middle-sized grain, Common fl-
soft enough to be cut with a toothed saw, easily pale ue er
ting ats grain to be rubbed out by the fingers, and yield-
-ing a fine powder, by rubbing two pieces against each
other.
J found its specific gravity to be 2°322. A piece, weigh- Spec grav.
ing while dry 102°155 gramines, weighed 114°5, after it had
lain ten minutes in water, though it was carefully wiped ;
which gives an increase of 12°545 grammes, or very near an
eighth of its weight.
_A hundred eae: of this stone dissolved slowly in Effervesced
diluted nitric acids and the carbonic acid gas evelved occa- with acids.
sioned a diminution of weight of 33-59, including the small
quantity of water, which it always carries off with it.
The filtered solution left only 12°11 of siliceous earth.
The lime precipitated by sulphate of pore gave 139 of
sulphate of lime.
Hence we may seiner the composition of this stone, con-
sisting of
Carbonate of lime eeoserese rece 87°89 ; Its component
RepINeixt tere eter ota tees atele. cielevia oct ahieiaie ete 12°11 aa, parts.
Bini esies 3 100
I was desirous of knowing the place where this stone was place where
found in strata of sufficient extent, to supply the shops that tS kept se-'
work it up into filters for water; but from all my inquiries, ©
and what information I could get, it appeared, that the in-
~ yentor of these filtering stones, who has thus rendered a real
service to society, has thought proper to keep the knowledge
to himself.
In consulting the description given by Mr. Brisson, how- Many similar
ever, in his Treatise on Specific Gravity, of the stones used stones used in
for building in Paris and its environs, from the collections egy
of Perrenet and Wailly, several are found to exhibit the
same characters so completely, that we cannot doubt their
Possessing
192
® ;
FILTERING STONE.
possessing the same properties, and being applicable to the
same uses.
- There are ten in particular, that resemble it in want of
hardness, and size of grain, and that are capable of receiving
into their pores from eight to twenty-five hundredths of wa-
ter: such are, among others, those from Maillet quarries,
at St. Leu, and from the quarries at Vergelet, Gentilly,
St. Germain, Conflans, St. Honorme, and Bouré, near Mont-
richard.
The same author mentions, in the series of sand stones,
under the name of filtering sand stone, a piece froma stone
“used as a filter, that absorbed a tenth of its weight of water;
True sand
stones absorb
much less wa- ,
tere
The proper fil-
tering stone a
carbonate of
lime, with "12
or ‘13 of silex.
Errours in de-
termining the
while the crystallized siliciferous carbonate of ‘lime of Fon-
tainebleau did not absorb quite four thousandth parts ; and
among the true sand stones, such as those used by paviors,
cutlers, &c. and even those in which the remains of organ-
ized bodies sometimes occur, there are none that admit so
much. These circumstances. lead to the suppesition, that
the specimen subjected to this trial by Mr. Brisson actually
belonged to a filter of the same kind as those now generally
used ; and that he gave it the name of sand stone, merely
from the preconceived notion, that the property of filtering
existed only in stones of this species. A
We may conclude then, that the filtering stone employed
for domestic purposes at Paris is not a a stone, but.a
carbonate of lime, containing only 12 or 13 per cent of si-
lex, in such a state of aggregation, as to leave pores suffi-
ciently open to admit water to run out of them gradually as
they imbibe it: that it differs not only from the sand stones
with siliceous cement, but likewise from the. argillaceous
sand stones, such as the grindstones of Geneva, Brives, &c.
which in time imbibe a pretty considerable quantity of water,
but let it pass through with much more difficulty: and that
several of the quarries I have pointed out from Mr. Brisson
may have calcareo-siliceous strata of the same nature, and
possessing the same property.
To remove all doubts on this head, it appears to me ne-
cessary to offer some remarks on the mode of. determining
the specific gravity of substances with large pores.
It may appear surprising, that I assign to the stone I have
i described
=a
‘@
SPECIFIC GRAVITY OF POROUS SUBSTANCES, 195
described and analysed, a specific gravity of 2°322; while specific gravity
Mr. Brisson gives no more than 1-232 for that of the piece aoe =
of filtering stone, which I have mentioned as serving to es-
tabish a similarity. But it must be considered, that, to ob= from supposed
tain this result, Mr. Brisson adds to the weight necessary to corrections.
restore the equilibrium, when the substance is immersed in
water, the weight of the quantity of water that has penetrated
at. Such was the method adopted by the author, for sub
stances capable of imbibing water, which appears to me to
require a farther examination, though followed by many nas
tural philosophers. It is true Mr. Brisson gives to the spe-
cifie gravities of these same substances a second expression,
derived from a calculation, in which the absolute weight, or
the weight taken in air, is increased by the weight of the
water absorbed. But neither of these expressions can give
the true ratio of the mass of matter to the actual place it
occupies; since in the first, that water is reckoned as dis«
placed, which only succeeds to the air that before occupied
the pores, and which ascends in bubbles from every part of
the surface; and in the second, the weight of the mass is
confounded with that of the fluid employed to circumscribe
its solid parts. me
In fact, if I had proceeded on this principle, I should But no correc.
have found the specific gravity of the filtering stone no more UOn Bessy»
_ imbibe and part with moisture so regularly, that they were capable of
; when the sub-
than 1°813, which comes very near to that assigned by Mr. — is sufhi-
: . + ciently per-
Brisson. On the other hand, if we apply to the data of his ae a4
experiment the simple calculation of dividing the weight of
the body in air by the weight necessary to add to restore
- the equilibriam when it was weighed in water, we shall have
as the quotient 2391, consequently still a little more than
the same calculation for the stone I examined gave me.
Sand ‘stones and filtering stones are not the only fossil Other fossils
substances, that receive into their pores the surrounding Penetrable by
medium. Chalcedonies, pitchstones, steatites, asbestos,
water,
mesotype, schists*, some micas, and eyen, according to
‘Gerhard, some varieties of jade, are more or less penctrable
_ by water.
- * Mr. Ludicke has described some hard schists, which he found to
answering the purposes of an hygrometer,
This
oe
\
194 SPECIFIC GRAVITY OF FOROUS SUBSTANCES. |
Spec. gravity | This property unquestionably ought to be noticed.in de-
regen i scribing them: it makes a part of the characters, the aid of
illustrating the which is requisite to the naturalist in discriminating species ;
few of bo- but when he seeks the true specific gravity of any substance,
it is to acquire a more intimate knowledge of its nature, not
to derive from the measure of a surface full of pores, and
roughened with asperities, a gross calculation of the solidity
of its mass, as if his object were the estimation of a load.
The problem, which it is of real importance to the pro-
gress of science to solve, is to determine the exact ratio,
that the proper substance of'the body under examination
bears to the bulk of its contiguous parts, that leave no more
spaces into which the surrounding fluid can have access.
The water, wiich is absorbed as the air escapes, can no more
be considered as water displaced by the solid, than that im-
bibed by a sponge; and we should fal] into a great error, if
Spec. grav, of WE were to estimate its density on this principle. It would
soluble sub- _ be superfluous to say, that in all cases we suppose the water
a. oe to have no chemical action, as it has on salts; for then the
ometer 5 hydrostatic balance could not even give an approximation to
the truth, and we must have recourse to Say’s stereometer * 5.
or if we have not this ingenious instrument, which is not yet
copanciechintl in very genéral use, we must employ a fluid that has no ac-
ina fluid that tion on the subject to be examined, as for instance, water
Fo sidenct completely saturated with the same salt, Thus I used a
ready saturat- saturated solution of nitrate of potash, when I was engaged
pipiens iss in the year 11, as member of the committee appointed by
in solution of the minister at war, to give a comparative table of the spe-
pane cifie gravities of all the different kinds of gunpowder used
“yn the fleets or armies of various nations. ,
_ The same principles led me to suspect, a few years ago,
Errour in re. the errour, into which most mineralogists had fallen, im
gard to pumice ascribing to pumice stone a specific gravity even inferior:to ”
a ag that of water. Mr. Klaproth observes, in his analysis of
that of Lipari, that, though it contains more than 0717 of
alumine, it is not at all attacked by acids: this, added to the
hardness ‘we find in its smallest particles, though they are
easily separable, indicate a state of combination inconsistent
* Seea description of it, Annales de Chimie, Vol. XXIII. p. 5.
seo | with
t
HEAD OF FLINT. 193
\
with the idea of rarefaction attached to such lightness. Itis
evidently owing therefore to the multitude of pores and hol-
low spaces, into which the water cahnot penetrate, to cir-
cumscribe the volume of the solid parts. Powdered pumice !ts spec. grav.
: ye : kee), 2149
i me oe 1x De O*. —
stone afforded me a specific gravity of anaes anid this-48 p) ous <ub-
the only method of weighing hydrostatically porous bodies, stances should
so as to obtain a constant expression of their density, truly °°“ shed ®
oo eY> ¥ powder,
comparable, and affording a just idea of the power of ag-
gregation possessed by their integrant parts, which is the most
important point, on which any light can be thrown by a com-
parison of specific gravities.
~ = «i
Report on a Sculptured Head of Flint, with a Covering of
Calcedony, made to the Physical and Mathematical Class
of the Institute, March 31, 1806. By Mr. Guyton t..
M R. MILLIN, our associate, of the class of history and 4 4; ae
ancient literature, having had an opportunity of examining mitted to the
a piece of sculpture found in the Faubourg du Roule, prone a
thought it his duty to offer it to the inspection of the phy-
sical and mathematical class, as an object leading to ques-
tious that were interesting both to mineralogy and the arts ;
and you have commissioned Messrs. Berthollet, Vauquelin,
and myself, to make a report to you on the subject.
The fragment was very obligingly entrusted to us by Mr.
Cerf, to whom it belongs. It was found, four months ago, wore found.
in the garden of a house, that was formerly part of the
Committee.
* See Annales de Chimie, Vol. KXIV_ p. 204
N.B. I did not neglect this method of verifying the specific gravity
of the filtering stone. I reduced it to a fine powder; and the moment it
was immersed in water, all the air interposed between its parts, or rather
that adhered to its surface, rose in one single bubble; and the loss of
weight indicated, without any correction, a specific gravity of 2-261,
which differs very little from that I mentioned before.
+ Annales de Chimie, Vol. LVUI. p. 75.
Chatean
196
Described
Tts age:
The flint co-
vered with a
thin coat.
“HEAD OF FLINT.
x
Chateau des Térnes, and is now a boarding-school for young
ladies. A gardener discovered it 11 digging up the ground,
at less than two feet deep. This was al! the mformation we
could get ; and nothing since has been discovered, that can
lead to the slightest conjecture respecting the time or cir-
cumstances-of its being buried there: but the singularities
it exhibits sufficiently excite the curiosity of the antiquary,
the naturalist, and even the artist, to induce us to attempt
to satisfy it, by an examination of what remains of it.
It is a head sculptured out of a piece of flint, of the same
nature and appearance as that of which eun-flints are made.
From the point of the chin to the crown of the head it is 9
cent. [34 inches], from the forehead to the back of the head
76 mill. [S$ inches], and its circumference, taken above the
nose, is 236 mill. [9% inches].
A hole 18 mill. [3 an inch] in diameter, in the lower part, ,
and still partly filled with gypsum mixed with lime, appears
to have served the purpose of uniting this head with the
body of the figure, probably formed of another piece of
flint, or perhaps of some substance more easily wrought ;
and which, according to the usual proportions, must have.
been 54 cent. [21 inches] high; so that the whole statue
would have been 63 cent [24% inches]. '
From the form in which the hair is dressed, it appears to
be the head of a man. The hair is shert, and confined by
a simple, narrow band, such as the Greeks and Romans,
wore ; which, added to the style of the figure, seems to in-
dicate an antiquity considerably prior to the times of the
Gauls; though-the apple of the eye is, mar ked out, which
very rarely occurs in really ancient works. -
But we shall leave to more competent judges the discus-
sion of these points, of which we thought a brief mention
necessary, to render the description of the stone: complete,
and place in its proper point of view the question, that has
principally engaged the attention of the class.
The flint, of which this head is made, has been covered,
in all the parts that have neither been broken nor worn away
by friction, with a fine white coating of a scarcely pereepti-
ble thickness, attackable by no acid, and uniting with a
hardness at least equal to’ that of calcedony the glassiness
oe _~ of
HEAD OF FLINT. 107 .
of an enamel, sufficiently transparent to allow the different
shades of the silex, more or less gray or bluish, to appear
through it in some places.
Is this coverin eg, for 1 do not-think it can be termed a crust, Is this natural
the work of nature,-or of art? eumenicc
It is obvious, that we cannot refer to analysis, to solve this Obstacles te
question; for thus the fragment must be destroyed, and 8 404!yss-
even then we should not obtain a sufficient quantity of the
_ covering to afford unequivocal results. Nay, should they be
certain and easy, they could inform us of nothing more,
than we know already. by its external characters of colour,
opacity, hardness, and unalterability in acids, that its con--
stituent parts are the same as those of calcedony.
The first idea that suggests itself on the inspection of this Appatently an
head is, that the block of flint, after having been laboriously roe
cut on the wheel, in the same manner as geims, received a co- -
vering in the fire of the same nature as that applied on the
biscuit m making porcelain. Not only do the glassiness of
the enamel, and its thinness, appear to afford grounds for
this opinion; but it is supported by comparing its shining
surface with the dullness of the white crust, on two frac-
tures occurring at the bottom of the left cheek, this crust
having been formed evidently ‘since it was buried in the
earth.
_ Buta large aud more recent fracture on the right side ex- But the flint
poses the silex retaining all its ordinary characters ; and it is Mae a oma
well known, that this Shictaniee loses its colour and trans- strong heat.
parencey in a fire incapable of fusing even feldtspar. The
fragment I subjected to this trial was exposed to a heat of
° of the pyrometer only, when it separated into several
_ pieces, and assumed the appearance of a biscuit to its inte~
_Ylor parts.
. This no doubt has led to a more general adoption of the probably
opinion, that the calcedony covering the silex can have been therefore na-
deposited on it only in the humid way, during its having been ona
in the ground. /
Before I embraced it, I thought it necessary to search
- among collections of minerals of: the same kind, for indica-
\ tions, at least, of the possibility of such a covering :being a
_-. natural. production.
q 4] : Tn
198 EAD OF FLINT.
‘
But itdoes not In these collections, flmts commonly appear encrusted
ee ae rather than covered; and the crust is dull, adheres to the
af other fints. tongue, imbibes acids, and even exhibits some signs of ef-
fervescence. There are some, it is true, covered with a
very hard calcedony ; but it is always thicker, less transpa-
rent, forming an uneven crust, exhibiting only a few shin-
ing parts in the fractures where traces of friction are percep-
tible, and never possessing the glassiness of enamel.
Calcedonies It might be supposed; that the polish of the cut flint
cies cae occasioned the glassiness of the calcedony that covers it, and
faces have not produced the difference appearing im the earthy calcedony,
vt obsh of that covers the two fractures: but the calcedony observed
on several rock crystals, on mamillary agates, and moulded
on cubes of fluate of lime or other crystals, the surfaces of
which may be considered as polished, never have this shining
aspect. aie
nor stalactitic. The stalactitic caleedony of Geysser, in Iceland, is equally
without the appearance of enamel, even on Surhices that
have been in contact with flat bodies.
nor hydropha- ‘The hidrophanous calcedonies, observed as forming thai
nous calce- » sitions in’ pitchstones, chert, &c. are likewise of a dull
ane white, frequently even in the recent fractures. They are
nor opal. always found in veins too, never as crusts; The same may
be said of the opals, the fracture of which, though of a more
vivid lustre, is always unequal, undulated, and exhibits no
appearance to the eye approaching the lustre given by po-
lishing.
Two calcedo- Two specimens however offered me a surface of sufficient
2 sale tle polish, to give no hope of finding i in nature a silex analogous
werenot | to this antique. One came from the department of the
bia Indre and Loire. {It appeared entirely covered with white
calcedony; but on breaking it, to examine its interior, I
perceived only a continued mass of the same nature, the
and! poleted surface of which had acquired its polish solely from ‘friction,
by friction, | which excluded all comparison.
The other specimen came from Siberia. One of its sur-
faces approached somewhat more in appearance a vitrified
enamel, and had a tolerable lustre: but it was quite as fo«
reign to flint and its transitions, since it was nothing but an
opake white calcedony, on a calcedony more transparent.
It
s
HEAD OF FLINT. 199
It was likewise intersected by reddish hnes, crossing each
other in different directions, asin the ludus Helmontii.
The doubts arisiig from this comparative examination in- Attempts to
duced me to inquire, Satcher it might not be the work of art, imitate it by
at least how near art could approach it. a4
I have already noticed. the facility with which silex is al-
tered by fire; we could not think therefore of employing the
processes by which porcelain is covered. - But might not the
same end be obtained, by cementations with a moderate
heat, long digestion, saline fusion, or combined solutions, .
to set at work powerful affinities? Chemical experiments
alone could throw light on this subject, and to them I had
recourse. .
- It will be sufficiént to give a brief account of the results
of the first unsuccessful attempts. ‘
Flint cemented in lime from marble, sulphate of lime, Unsuccessful
sulphate of alumine, and muriate of soda, underwent no trials.
alteration, as long as the heat was not carried to a certain
point. Beyond that it began to lose its colour, transparency,
and tenacity.
A fragment of flint treated with caustic potash ina pla-
tina crucible experienced only a trifling diminution of
weight, more or less in proportion to the time in which it was
continued in a heat sufficient to keep the potash in fusion.
Alumiue being one of the constituent parts of calcedony, Alumine with
though in a small proportion, I conceived, that by treating °° nape: ee
the flint with a solution of potash saturated with alumine,
and adding a portion of free potash to act on the silex, the
affinity these two earths have been shown to possess for each
other*, and with a common solvent, must eitect on the sur-
face of the silex a new combination, at a temperature inca-
pable of altering its nature.
_ Considering on the other hand, that analysis had developed and the same
in some calcedonies the presence of lime, 1 put a.simall With Pep onigs
quantity with another piece of flint into a similar preparation Ss ‘Beso
of potash and alumine. milar coat,
These two experiments were .made in platina crucibles,
-and the success exceeded my expectations, though they were
* See our Journal, Vol. LY. p. 164
not
200 HEAD OF FLINT.
not preceded by any trial, to adjust the doses of the agents,
and the duration and intensity of the fire. The flint was not
altered internally ; it only acquired a very thin coat on its
surface, of a uniform thickness, united into one body with
the mass, unattackable by acids, and of such hardness, that
of great hard- it rapidiy wore away the stones used by lapidaries, and was
— as impenetrable to adamantine spar, or corundum, as the
coating of the sculptured head.
and capable of The pieces came out of the crucible of a dull white, as I
a fine polish. hye } ee
expected ; but some parts, which I had polished in the same
manner as hard stones, showed them to be capable of as good
a polish as the head found at Ternes.
The artist It cannot be denied, that such a complete imitation favours
might haye ee : . oat
employed this the opinion of the coating having been a;work of art. . It is
process, not necessary for this to suppose, that the chemical affinities,
though igno-- ,. SUC neM ees i
rant of its Which Jed to this imitation, were known to the artist whe
theory. executed the antique: for it would net be the first. process
found out by loose trials, and practised with success for cen-
turies before the true theory was discovered. |
This opinion This opinion however has not obtained general penne
still questioned Those who contest it rely chiefly on the resemblance of the
sre ay coating of several flints found in the environs of Ternes, spe-
similar coat, .cimens of which were shown to the class by, Mr. Chaptal ;
; and which in fact exhibited on some of their faces parts, of
an enamel, if not equally uniform in tint and in thickness,
at least as glossy.
Still apparent- Others have thought with Mr. Fourcroy, that, whether
ly polished at the coating of the sal picid head were formed in the.earth,
least by art. :
in the same manner as the crusts of. these flints, or added by
an artificial process after it came out.of the sculptor’s hand,
_it must be admitted to have received its polish from. art ;
and that this was the only way of xeconciling the inferences
we are obliged to deduce from its present state, :
Under these circumstances, the committee can only. pro-
pose, to the class to suspend its judgment, and,to leave the
subject open to farther inquiry and discussion, for the solu-
tion of a question interesting to the history of the.arts, and
to the sciences of the antiquary and the naturalist.
Xt.
:
EXPERIMENTS ON DOUBLE VISION. 201
XI.
Experiments on Doubie Vision by Dr. Hanpar, Secretary
to the Academy of Nancy.*
Tur superiority of single vision, or vision with one eye, Se ge |
over double vision, or with both eyes, has long been the 84rly supposed
ba i yt P sage bs to be most dis-
subject of two opposite opinions. It is maintained by the tinct,
vulgar, that single vision is most distinct. Philosophers on
the contrary assert, that we see better with two eyes, than
with one. The latter opinion, established by father Che-
rubin in his treatise on distinct vision, and placed beyond ee
all doubt by Dr. Jurin, by means of an experiment, which Jurin.
consists in looking at a sheet of white paper, with a piece
of pasteboard, or other opake substance, affixed to the
right temple, and projecting so far forward, as to conceal
half the sheet of paper from the right eye, while the whole
is visible to the left. On looking at the paper alternately
With one eye and with both, we perceive very distinctly,
that the part seen by both eyes is much brighter than
that seen by the left only : the former appears with all its
natural whiteness, while the latter appears as if shaded by a
thin ‘gauze. Dr. Jurin even estimated the intensity of this
obscuration by a very ingenious photometric contrivance.
If this experimental proof of the superiority of double Hea
vision over single wanted farther support, we might adduce
the experiments made by means of binocular telescopes,
the superiority of which have been acknowledged by all ob-
servers, both for distinctness of vision and magnifying
power, over single instruments magnifying equally, and of
équal clearness.
From this well established fact, that double vision pro- A double sen-
bane , A 3 AG sation produces
duces a more vivid and distinct sensation than single, it fol- a single percep-
lows, that the sensation produced by the impulse of light tion.
, on one of the eyes is reinforced, if I may use the expres-
sion, by that produced on the other; and that consequently
a complex sensation may give rise to a simple perception.
But does this faculty of forming simple perceptions, when But may two
* : . different sensa-
the impressions are complex, equally take place in all cases? tions be blend-
Is it the case when the impressions are heterogeneous, as ¢d into one?
:
* Journal de Physique, Vol, LXIII. p. 387, Nov, 1806.
You. XVIL—Jczy, 1807. P well
" EXPERIMENTS ON DOUBLE VISION.
ww
So
CS)
well as when they are homogeneous? Such is the question
I propose to resolve. I confess, however, that 1 was led
to the experiments, that constitute the subject of this me-
moir, by an accidental circumstance, on occasion of an
eclipse of the sun, the progress of which I set myself to
An eye viewing observe. The instrument I used not being farnished with a
an eclipse with- f
outa dark glass, Coloured glass, my right eye was so much affected by it,
ve sight was that it was deprived of distinct vision for somedays. When
estroyed fora , J ;
time, and after- 1t began to recover, all white objects appeared to me to
wards repre- have changed colour, and acquired a reddish hue, the
sented objects § °
red, depth of which I could alter at pleasure, by looking at
them with both eyes, or with the affected eye alone, When
This blended J looked at them with the right eye, which had been over-
De, cher strained, they had a red hue; when with both eyes a rose co«
both eyes were lour; when with the lefteye only, white as usual. This fact,
ose the explanation of which is foreign to my subject, led me
to conclude, not only that the perception produced by the
impulse of homogeneous light on one of the eyes was_re-
inforced by that from a similar impulse on the other; but
that the impression of heterogeneous rays on each of the
two eyes might give birth to a complex perception, which,
being composed of both sensations, would be a mean bee.
tween the two.
Experimentson Desirous of satisfying myself whether the impression of
er gn 4 ail the primitive colours, applied separately and simultane.
betweenthe ously to both eyes, would constantly produce a complex
ae the sensation analogous to that I have just related, I determined
to procure myself transparent coloured mediums, which,
suffering rays of one sort only to pass, might, by being ap-
plied separately to each eye, subject this double organ to 2
complex impression. The difficulty of procuring myself
coloured glasses of allthe tints, or colours sufficiently trans.
parent to paint similar ones to those of magic lanterns, in-
duced me to reject these, which would have been more
convenient, and have recourse to hollow quadrilateral prisms
of white glass, into the cavity of which I poured liquids of
a proper colour and tint for all my experiments.
Thoice of co- The choice of tingeing substances for colouring the wa.
prans i.3 ter, with which the prisms were filled, requires some pre-
cautions, of which it may be proper to inform the reader ;
not
EXPERIMENTS ON DOUBLE VISION. 903
not only because all colouring substances have neither the
same solubility nor the same transparency, but because Many not the
they have not all the same tint by reflected and refracted sea eas ig
‘light; as Spallanzani observed with respect to the globules tion.
of the blood, which appear red or yellow in the microscope, Blood,
according to the manner in which they are acted upon by
the light. It has long been known, as may be seen in
Newton’s Optics, that the lignum nephriticum exhibits a Nephritic
phenomenon of this kind. The infusions of violets and li- bashes
iolets, litums.
tums, which have a pure blue tint by reflected light, have
2 decided violet by refraction. Butit is particularly diffi-
cult to obtain the desired tints among the yellows. Those Yellows,
that are the purest yellow by reflected light have a decided
orange by refracted. They can only be divested of this red
hue, that alters them, by filtering them a great many times,
after diluting them with a considerable quantity of water.
This effect, which depends apparently on the opacity of the
colouring particles, and the force with which they repel the
most easily reflected rays, and admit only those that are the
least, seems to me well adapted to explain most facts of this
kind. In reality it is the least refrangible colour, the red, _
that generally produces those differences observed in colour- nae
ed mediums by reflected and refracted light; and these dif. cause.
ferences are diminished by weakening the tinctures, and di-
luting them with water.
Two prisms of glass being filled with different coloured Glass prisms,
liquors, and applied oie to each eye, if we direct both eyes ae airetow
at once to the same object, we receive a double impression, applied before
the perception corresponding to which is simple, and that the eyes.
of the colour resulting from a mechanical mixture of ana-
logous colouring substances. Thus a yellow prism, and a
red prism, applied one to the right eye, the other to the
left, produce the sensation of orange, as a mixture of ver-
milion and yellow ochre would do. But not to enter into
tedious details, I shall give a tabular view of the results of
the numerous experiments I made on this subject.
As the results of these experiments cannot be exact, un- Cautions.
less the colours be distinct and pure, in reflecting the light
toward the eye we ought to exclude two kinds of bodies,
those that are too bright, and disturb the sight by their
EY glare ;
204
Method of
making the ex-
periment.
Resuits-of the
combined per-
ception of dif-
ferent colours
by refraction.
The colouring
matters that
were employed,
EXPERIMENTS ON DOUBLE VISION.
glare; and those which, reflecting colours proper to them.
selves, vitiate the results: such as candles, lamps, &c.:,
which diffuse too abundant light-in yellow rays. The best
method is to take a piece of white paper, about eight inches —
in diameter; place itona black or brown ground at the
end of a moderately light room opposite the window, and,
standing two or three yards from it, with the back to~the
window, look at it with both eyes, each having its proper
prism before it. In this manner I obtained the following
results.
Red and yellow produced orange.
Red and orange aurora.
Red and blue violet.
Red and violet a pleasing rose colour.
Red and green a muddy red. |
Red and indigo an indeterminate colour. .
Orange and yellow light orange.
Orange and blue muddy green.
Orange and green light green.
Orange and violet muddy rose colour.
Yellow and blue - muddy green.
Yellow and green light green,
Yellow and violet harsh red.
Blue and green sea green.
Blue and violet a deep violet.
In order to enable those who wish to repeat these experi-
ments to execute them with greater facility, and render the
results uniform, I shall add here an account of the colour-
ing substances, that were employed. The red was a decoc.
tion of brazil brightened by an acid. I likewise employed
for this colour red wine, and a decoction of cochineal. The
yellow was prepared from quercitron bark, the decoction
of which must be weak, well filtered, and brightened: the
orange, from French berries, or turmeric: the blue was
aqua celestis, a solution of copper in ammonia: the green,
an infusion of mallow flowers changed by potash: the violet
was prepared from litmus and violets. These experiments
are easy to execute; they only require a little practice, and
the habit of distinguishing different tints of colour.
After
EXPERIMENTS ON DOUBLE VISION. 2905
’ After having thus proved, that coloured rays of a dif- Experiments
ferent nature, obtained by means of refracting mediums, tt era
produce the perception of a mixed colour by their separate ig
action on the eyes; I was desirous of satisfying myself,
whether these effects would equally take place from light
reflected by different bodies, and reccived immediately by
the eyes. But asit was necessary for this purpose, that
the organs should be placed in such a situation, as to render
the impression received by each eye totally unconnected
with that received by the other, I separated the bodies sub-
jected to the experiment by a thin opake plane, placed per-
pendicularly between the two eyes. The little apparatus Apparatus,
I employed consisted of a square piece of wood, on the
middle of which was placed a very thin vertical plane, the
upper edge of which was applied against the forehead and
nose, so as to separate the two eyes. The whole of this
apparatus, which was twelve or fifteen inches high, was
painted black in distemper. The coloured surfaces, the
double impression of which was to be observed, were placed
parallel to each other on the base, one on each side of the
vertical plane. These coloured surfaces were little pieces
of pasteboard ten or twelve lines square, painted in distem-
per, and representing the primary colours. It is necessary
to have some smaller, and some narrower, and particularly
to be provided with at least three shades of each colour.
The apparatus for double vision being placed opposite a yfernoa of
-window, and the pasteboards on each side of the base, the using it.
forehead is to rest lightly on the upper edge of the vertical
plane, and then, viewing both objects with great attention ,
at the same instant, the effect of the double impression will
_be perceived. The phenomena that accompany or precede Phenomena.
the complex sensation resulting from it are worthy notice.
1, When with steady attention, for about half a minute,
or even longer if necessary, we see the objects evidently
approach each other, and the plane that separates them The objects ap-
disappearing, they: gradually encroach upon each other, ean a A
till they are entirely confounded together, if the distance other,
from which they are observed be in proportion to the mag-
pitude of -the little pieces of pasteboard; as that of twelve
or
906 EXPERIMENTS ON DOUBLE VISION.
till they begin or fifteen inches. 2. In this apparent progress of the bodies.
to overlap ; and toward each other, they approach with a pretty regular
then blend at motion, till they partly cover each other ;; when we see
dae them suddenly confounded together, as at one leap; and
then the compound sensation is changed into a simple per-
ception, and only one single object is discerned, the colour
of which is the result of the combination of the colours .of
the two pieces of pasteboard. All the primary colours,
subjected to the same trial, afforded me analogous results,
indicated in the following table, a few modifications except.
ed, which I shall notice.
Resulteofthe Red and yellow produced orange.
ee Red and orange a bright aurora.
fecent colours ed and blue violet.
by reflection. Red and green a rosy green.
Red and violet a rosy violet.
Red and indigo a dingy violet.
Orange and yellow light yellow.
Orange and blue muddy green.
Orange and green reddish green.
Orange and violet light violet.
Orange and indigo harsh violet.
Yellow and blue faint, indeterminate green.
Yellow and green light green.
Yellow and violet muddy green.
Yellow and indigo a dingy green.
Blue and green deep or light green, accord.
ing to the shade of blue.
Blue and violet deep violet.
Blue and indigo “ deep blue.
Green and violet a dingy violet.
Green and indigo _ avery deep blue.
The experi- These experiments, though not difficult to execute, re=
ments require . . : ° :
practiceand ire a certain practice, and steady attention, without
attention, which they will not succeed. The strong convergence ne.
oe ee cessary to be given to the optic axes renders them fatiguing.
*T have met with several persons, who, not being able to
keep up their attention, and view the two objects steadily
at one time, did not experience the compound sensation,
or
EXPERIMENTS ON DOUBLE VISION. . oe
or the perception resulting from it: practice however -has
rendered it very familiar to me, as well as to several per-
sons, whom [ have employed to repeat them.
As the perception of the mixed colour in these experi- All colours do
- : : not blend with
ments results from the impression made by two objects of equal case.
different colours, and received simultaneously by each or.
gan of vision, it would seem, that all colours, being equal.
ly capable of producing’such an impression, should occa
sion a sensation equally complete and distinct, and produce
it with equal facility. This however is not the case: several , :
of them combine but imperfectly, or not at all. The com-
bination of blue and yellow for instance is not only pain- Blue and sel-
ful, on account of the continued attention it requires, but Laima
the colour resulting from them is vague, nearly indetermi-
nate, and of a disagreeable hue. This singular anomaly,
the most remarkable that occurred in these experiments, is
not sufficiently accounted for by the extreme difference and
-heterogeneousness of blue and yellow; since blue and red,
which are equally heterogeneous, combine easily and com-
pletely to produce a violet. The property of. illuminating, -7);, brite ite
which these colours possess in different degrees, confirmed a difference in
by Newton, and subsequently by Herschel, is the only eae
circumstance, that appears to me capable of giving a plau- -
sible explanation of it: for this property of illuminating
depends on the force with which the colours act on the eye.
Thus when two colours possessing this property in different
degrees act at once on the two eyes, the too powerful im-
pression on one necessarily renders that on the other less
sensible, and the mixed colour produced by this double im-
pression will not therefore be very distinct. This appears fence blue
to me the better founded, as the green is more distinct purine
when the yellow is weaker, and the greenish tint produced ‘
by the combination of blue and yellow appears to contain the yellow has
much more of the latter colour than of the former: and eee its
further, if the impression of the yellow colour be weakened | 4 4.0 pest
by the interposition of a semitransparent substance, the green is produc-
green is rendered much more determinate. Both yellow mn A cela
and orange combine very difficultly with blue and violet,
while they combine together, or with red, very easily.
Homogeneous
208 EXPERIMENTS OX DOUBLE VISION.
Homogeneous Homogeneous colours of different shades combine witht
Se the greatest facility. Thus a strong red and a faint red give
a mean tint of red. What appears very astonishing is, that
ee ae black and white comport themselves as pigments of the same
with and modi- Colour would do. White, which is the result of a union of
fy all colours. a]! the primary colouring rays, renders colours lighter, as
a mechanical mixture of a white powder would the pigments
that represent the other colours. ‘Thus red and white give
a flesh colour. Black, which is merely the absence or pri-
vation of colour, might be supposed to produce no effect on
the organ of sight; yet it has just the same as a mixture of
any black powder would with the pigments that produce
other colours. ‘Thus light blue or green with black gives
the perception of dark blue or green. Glaring colours,
such as red and orange, less readily associate with black :
but white and black, the white pasteboard being placed on
a black ground, and the black pasteboard on a whi 4
ground, produce the sensation of gray, like a mixture of
ivory black and chalk. 4
: I should tire the reader, if I were to relate all the differ,
ences I have observed in colours with respect to the degree
of facility with which they combine, or rather associate the
effects they produce separately on the two eyes. But}
cannot pass over another class of facts, which pertain ta
the same theory, and may serve to elucidate it. These facts
‘Double vision relate to the double vision of objects resembling each other
ern rae in colour, but differing in form, or differing both in form
Parallelograms and colour at the same time. Little parallelograms of paste-
placed in oppo: board, either black, white, or of various homogeieal co-
lours, twelve lines long and four broad, placed on the op.
posite sides of the vertical plane of the apparatus, one pa-
rallel the other perpendicular to the plane, exhibit the
form across, appearance of a cross with equal arms. Two equal disks,
eight lines in diameter, placed on opposite sides of the same
vertical plane, are so blended together, that itis impossible
to distinguish them. +Parallelograms like those just des.
and theirce- eribed, or squares of unequal size, if of different colours,
ieee exhibit by double vision crosses or concentric squares, the
join. place of junction or superposition of which exhibits the
mixed colour,
1 shalt
EXPERIMENTS ON DOUBLE VISION, | 209
' Yshall not enlarge on this article, as theory alone is suf- In all cases one
ficient to determine all the cases of alteration of figure by ea ae
double vision; for it is sufficient to imagine the two objects other.
‘placed one upon the other, the effect which double vision
produces. |
I was not satisfied with thus combining the primary co- More than twe
Jours by pairs only, but extended my researches to more hires:
numerous and complicated associations, which led me to
some remarkable results, that could not have been deduced Four colouss
by analogy alone from the simple association. ‘The first of aue tis abs
these results is, that it is possible to receive at one time two
‘distinct and comparable sensations by the simultaneous im-
pression of several objects on our eyes. Little parallel.
ograms of red, blue, yellow, and green, placed parallel to
each other, and on opposite sides of the vertical plane of
. the apparatus, in the order [ have mentioned, aiid subject-
ed to double vision, give the perception of orange, produc-
‘ed by the association of red and yellow, and of sea green,
produced by the green and the light blue.
The second remarkable result is, that the colours, in They havea
their apparent associations or combinations, seem obedient ruth ripest’
to a kind of affinity, by virtue of which those that haveseck ou’ those
most analogy to each other combine in preference, be owed be
disposition of the parallelograms. what they may. Thus
the yellow combines with the red, and the blue with the
‘green, let them be disposed in either of the following modes:
‘yellow, blue, red, green; or yellow, blue, green, red;
‘or blue, yellow, red, green; arrangements in which the
‘colours are obliged to jump over one another, if I may use -
the expression, to seek out and combine with those analo-
gous to themselves. This tendency of certain colours to This perhaps
‘combine together in preference to others appears to me to ae “
be the principal cause, that opposes the recomposition of al} into white
light by placing all the primary colours on each side'of the !ight.
‘vertical plane, which I at first hoped to have effected.
The experiments on double vision by means of reflected The cfects of
and refracted light suppose a third class, composed of il eh chee
‘eombination of the processes of the other two; but, as together ae
there is no éssential difference in the results, I proceed to ‘#4?
explajn these phenomena,
| The
210 EXPERIMENTS ON DOUBLE VISION.
Enumeration of ‘The facts established by our experiments, and of which
the facts. we have to give the-proof, may bereduced to the following.
1. Simultaneous and separate double vision of objects
differing in colour produces a mixed or compound sensation,
which gives rise to a simple perception, similar to that
which. would be produced by a mechanical mixture of co-
louring substances, representing the colours combined.
2. Objects differing in figure, and similar in colour, com.
bine their figures, as objects of different colours do their
colours. :
3. Colours in their association, or apparent combination,
by double vision, seem to obey a kind of affinity, which
renders it more easy between some than between others.
Reason why a The explanation of the first fact is deducible from the
srt ple ee iuecaCO™Mon laws of our sensations. Perception being gene~
tion Is produce
by acompound rally proportional to the sensation, and this to the im-
sensation. pression made on our organs, a stronger impression must
occasion a more lively sensation, and consequently a pro-
portional perception. Hence when an impression is double,
from being received by both eyes, it must be heightened.
The perception however will not be double, because we
distinguish similar impressions with difficulty ; and under
the same circumstances, and by the same agents, we are sus-
ceptible of impression only to a certain degree.
The facts respecting the apparent combination or asso-
ciation of objects of heterogeneous colours, by artificial ~
double vision, offer several questions to be solved with re«
Why do we not spect to their cause. The first and chief, with which all
ay clei 4 the others are connected, is to know why, in these experi-
when both are ments, a double heterogeneous impression does not occa-
seen by each sion a double perception, as when we see two objects with
eye? .
d both eyes at once; and why on the contrary there is
but one perception, as when we see a single object with both
eyes.
Hypotheses of Lo explain this common phenomenon of vision, physiolo-
physiologists gists have invented divers hypotheses, which I have at-
OnsLIBLE TISION tempted in vain to apply to the explanation of my experi-
ments. Some have asserted, that perception was simple in
Union of the consequence of a union of the optic nerves, which, being
optic nerve > dependant on each other in their functions, could therefore
produce
EXPERIMENTS ON DOUBLE VISION. 211
produce only a single perception: others, that, as similar and in capacity
impressions cannot be distinguished, we have but one per- pliers Sagal
ception, though there are two impressions. But it is easy to ceptions.
see how far these hypotheses are from affording a satisfactory These unsatis-
explanation of the phenomena: for it is evident, that, ac- SE:
cording to the one, we can in no case distinguish similar
objects; and according to the other it would be impossible
for us ta besensible of the compound perceptions established
by our experiments.
The explanation of the physiologists who tell us, as wellas that
that perception, being recoived in a simple subject, Laois ieee
cannot be otherwise than simple, by no means elu- received ina
cidates the question. Whatever opinion may be enter- ‘imple subject.
tained of the cause of our sensations, it is certain, that Faculty ofcom-
‘we have within us a power that tends to individualize, ere
to identify with our being, the different sensations we expe- neous sensati-
rience at the same time. Thus in a piece of music we do °'”
- not distinguish the sound of any one instrument in parti-as of sound,
cular, or the effect of any of the parts that compose it:
we receive only a simple perception, resulting from these
manifold and simultaneous impressions. Thus two dishes, in and of taste.
which the refinement of luxury has combined substances
of the most heterogeneous nature, occasion only a mixed
taste, without our being able to distinguish any of those
of which itis compounded. But desirous of obtaining a
“more accurate knowledge of this faculty of identifying
and combining simultaneous heterogeneal sensations, I at- Experiments of
tempted to make experiments on the smell and taste analo- Chiat leiden
gous to those on the sight, and this by means of hete- scarcely practi-
. yogenous flavours and odours of equal solubility and “>!
volatility.
As I was unable to preserve the action of heterogenous Experiments
‘agents on these senses sufficiently distinct, to obtain satis. 0" the hearing.
factory results, I attempted analogous experiments on the
sense of hearing, which, as it consists of a double organ
like that of sight, was better adapted to my experiments.
I took two leaden speaking trumpets, covered exteriorly Apparatus.
with wet cloths, and introduced their extremities, ~vyrapped
‘ round with tow, one into each ear. ‘These were employed
to isolate the sounds of two monocords, which I intro-
duced
2
9342 EXPERIMENTS ON DOUBLE VISION.
w
duced into them, so that the sounds excited in one of the
organs were kept distinct from those excited in the other.
Sounds inpres- On making the strings of these Nttle instruments vibrate at
si aie the same time, I convinced myself, that the different im-
combine. pressions produced by different sounds combined in the
same manner, as when they are received simultaneously by
~ thesame car. The monocords tuned to thirds, fourths, or
fifths, to cach other, produced the perceptions correspond-
ing with those concords. IT know not whether it were
prejudice, but these concords seemed to me better united,
and more lrarmonious, that when received by the same
ear.
These facts, and many others of a similar nature, leave
no doubt, that we enjoy the faculty of identifying or com-
bining heterogeneous sensations. However, as we can
likewise experience a distinct perception of heterogeneous
This faculty and simultancous impressions, it is evident, that this fa.
dependant on ‘ é Spee ;
circumstances, CUlty is not so inherent in our organization, as to be inde.
pendent of certain cireumstances, without which we cannot
Instance in — produce the effects that characterise it. Thus we cease to
an atan experience the perception that results from the apparent
combination of heterogeneous colours, when the objects are
at too great a distance from the vertical plane that separates
them, or of too great extent.
We see objects These circumstances well considered have enabled me to
eS oS reduce these facts to the common laws of vision, ‘accord-
judgment is ing to the theory of Buffon and Condillac, which is that of
engi by the the majority of physiologists. Objects according to these
philosophers appear to us single, though there is a double
representation of them, one at the bottom of each eye,
because the touch, which corrects the judgment formed
by the siglit, teaches us, that the object, which we see
afterward from double, is notwithstanding single. Habit and experi.
ae ence haye rendered this manner of seeing so necessary,
that it.is impossible for us to change, without disturbing
the order established between the sight and touch. But
as every object, that produces a double impression on the re.
tina, is necessarily in the point of meeting of the optic axes,
and consequentiy painted on corresponding points of the
retina; and that itis with respect to this correspondence of
the
‘
EXPERIMENTS ON DOUBLE VISION. 913
the images on the two retinas, that the habit of judging Hence a single
an object seen double to be single is established ; an object piartal neg)
will appear double, whenever this correspondence does not the correspon-
take place. This happens when we press upon one of a eins)
the eyes in such a manner, as to determine the impression eyes is altered,
of the image of a single object to parts of the two retinas —
that are not commonly acted upon simultaneously, This sen
happened, as Cheselden relates, to aman who had one of is lcamed from
his eyes distorted by a blow; and he saw objects double, ®?*-
till habit and experience had done for the new points of
correspondence on the two retinas, what they had before
effected for the points that corresponded previous to the ac-
cident.
Double objects will appear single on the contrary, when Hee tean
their impression being made separately and simultaneously ington com
on corresponding points of the retinas, we experience the cc CORES:
same impressions, as would be excited in us by the picture .
of a single object. This is what takes place in our expe- pitied
riments: for the two eyes, in consequence of the vertical jimenis. 3
plane that separates them, receiving separately different
and simultaneous impressions on points of the retinas which
are the same, or nearly the same, as those that correspond
by habit to the two images of a single object, must excite
in us the idea of the presence of a single object only. What
convinces me that this association or combination of the
double image depends on its being depicted on correspond-
ing points of the two retinas is, that, when this corres-
pondence is destroyed by placing the objects at too great a
distance from each other, or by giving them too great extent,
the association does not take place, and we have a distinct
perception of the images of both objects. This in fact
must be the case, for the rays proceeding from one object
to both eyes necessarily observe certain proportions of cor-
respondence, which cannot exceed a given limit.
The superposition and apparent motion of the two objects The motion of
one toward the other is an illusion produced by the force re inks
of habit, which, having constantly taught us, that objects, other an illu
the double image of which is painted on the bottom of our “°™
eyes, without exciting a double perception, are placed in
the point of meeting of the visual rays, transfers them to
| 5 the
914 - =XPERIMENTS ON DOUBLE VISIONi
the point where we see them habitually. This allusion is
the more unavoidable, because a single perception always cor-
responds toa double image, and a double image is necessarily
produced by a single object seen by both eyes ; but in our
experiments, from the interposition of the vertical plane,
one impression only is received from each body, while with-
out this plane we should receive two impressions from each,
that is to say a quadruple image would be formed.
The combina- Lhe apparent combination of heterogeneous colours is
tion of colours another necessary consequence of this allusion, of this ap«
accounted for. ; . :
parent displacement of the objects; for we experience the
sensation of mixed colours, as often as their united elements
produce their impressions conjointly on the organ of sight.
Thus a mixture of blue and red wool gives a violet colour
to the cloth made of it. Here, though the colours act
separately on each of the two eyes, it is on points, the
correspondence of which is so confirmed by habit, that
only one perception can result from them, which is con-
sequently composed of the different effects of the double
impression.
That of figures I say nothing of the phenomena of the association or
a same combination of figures, its theory flowing so naturally from
what has already been laid down, that a particular explas
Affinity of co- nation of it would be superfluous. As to the greater or
lours simliar to Jess facility, with which heterogeneous colours combine by
that of concords rea ial gaa : A
in music. double artificial vision, it is explicable in the same manner
as the different effects of concords on the ear. In the same
manner as there are sounds, the association of which is
disagreeable, because their proportions are perceived with
difficulty, there are colours, the heterogeneousness of
which renders their association laborious, and consequently
not pleasing. I cannot discuss this question more amply,
without entering into the depths of the theory of sensations,
and wandering from my object, which was to make known,
and to reduce to the common laws, some remarkable
facts, that add to the number of illusions we expe-
rience from the wonderful but not very accurate organ of
sight.
Experiments
EFFECTS OF HEAT ON THE ANIMAL ECONOMY. 915
XII.
Experiments on the Effects produced by a high Tempera-
ture on the Animal Economy: by F. F. De taArocue,
of Geneva.
(Concluded from p. 149.)
Seer. II. Of the Degree of Heat Man is capable of |
supporting.
PaystoLocists have paid much more attention to the Experiments of
effects of heat on man, than to those it produces on other a HACE
animals. The extremely interesting experiments of Drs.
Fordyce and Blagden leave little to be desired on this head :
yet I thought it not amiss to repeat some of them, in order
to determine whether other individuals would be able to en-
dure heat as well as those gentlemen. For this purpose
Mr. Berger and I shut ourselves up in a room heated by a
stove, our bodies being naked, and defended from the radi-
antheat by a linen screen. We estimated the temperature
by a thermometer hung against the wall, four feet nine in-
ches from the floor.
Experiment I.
Temperature of the room at the beginning - 189° -5 Fahr. Temp. from
attheend - ~ 194 1 eeanen
Tentered the roomat - - > - - - = = 3h. 17m. — 8 minutes,
materi ie itd) abe A eels a Le SE! Sham)
Weight of my body when I entered - 128\b. 1loz. 3gr. loss in weight
ten minutes after I came out - © 128Ib. 5o0z. pee .
On entering I felt pretty sensibly the impression of the Other effects
- het air, but without being inconvenienced. In four minutes
’ afew drops of sweat appeared on my forehead. In five
minutes all my body was covered with a copious perspira-
tion. At this time I began to feel a little weakness, and
difficulty of breathing, which continued to increase, and
obliged me to quit the room.
Expériment II.
. Temperature of the room at the beginning - 194°. From 194° to
attheend - - 189°°5, 189° °5,
: Mr.
216 EFFECTS OF NEAT ON THE ANIMAL ECONOMY.
13 minutes; Mr. Berger entered itat + + - - + + 3h. 41m,
left \it/at.,...J7 2) a0. = 7) th, 54m.
loss near 11 oz. Weight of his body when he entered - . 105ib. 202. |
five mimutes after he came out + 104)b..7o0z. 6gr.
Othereffects. On entering he felt a slight burning heat at the nostrils
and round the nipples. ‘The perspiration, Brhich began to
appear on his forchead in four minutes, flowed copiously
from all parts of his body two minutes after. _ At coming
out he felt a little weakness and even faintness. His pulse
the instant before beat 128 in a minute.
agers iil.
From 228° 8 Temperature of the room at the beginning - 228° 3,
teeppeal at theend + - 225°°5.
Mr. Berger entered itat - + - - - - 4h. 32m.
leftitat = = =< = = 4h Some ..
loss 7oz. 138". “Weight when he entered - - - - 1031. 150z. 3gr.
ten minttes after he came out - 103Ib. 802. ligne
Other effects. He felt a pretty sharp burning round the nipples, at the
f nostrils, and even all over the face. In four minutes he
was covered with a copious and general perspiration. When
he came out he was weak and ill. A moment before he was
not able to count the beats of his pulse. Three quarters of
an hour after he came out he had recovered his natural state.
Cee cet. These experiments agree entirely with those reported by
Save feats in. Sir Charles Blagden in showing, that man is capable of en-
individuals. during exposure to very high degrees of heat for a short
space of time: but they show likewise, that there is a great
difference between individuals with respect to this capacity.
In these experiments Mr. Berger supported heat much better
than I, as appears obvious on comparing them. On the
other hand, if we compare them with those of the English
philosophers, we shall find, that they, or at least Sir Charles
Blagden, suffered much less from the heat than Mr. Berger
himself. In fact in one experiment he endured for eight
minutes a temperature between 240° and 260°, without ex.
periencing more inconvenience, than Mr. Berger did after ~
staying seven minutes ina temperature of 227° -8. Another
time Sir Charles Blagden was exposed for twelve minutes to
a heat of 222°, without suffering any inconvenience but a
little weariness,
7 minutes,
oO aes
EFFECTS OF HEAT ON THE ANIMAL ECONOMY. 21%
‘Mr. Delaroche made a’great number of experiments too Heat applied
on the heat both men and animals are capable sf enduring in Pe SS
baths of hot water, and in vapour baths; on the in/luence
sheat exerts on respiration; on the connexion that exists be-
tween the evaporation of the perspirable matter and ihe fa-
culty animals possess of producing cold; on the infiuence
of heat on respiration; and on the state of the bodies of
animals destroyed by excess of heat.
He concludes his labours with the following observations.
Such are the inquiries I have made, with a view to inves- The subject not
tigate the effects of a strong heat on men and animals.. J exhausted.
could have wished to have extended them farther, and ren-
dered them more complete: but the time such a labour
would have required, and the difficulty attending it, did not
permitme. I cannot therefore deduce from them general
consequences, but I shall briefly recapitulate the results General results.
they afforded me.
1. The object of my first experiments was to determine Small animals
the degree of heat requisite to destroy animals; and from Pea nae ie
them I learned, that small animals perished on exposure to at 133° 25.
‘a heat of 144° -5, or even of 133° -25. It is even proba-
ble, that a lower heat, but longer continued, would pro-
duce this effect.
2. Mr. Berger and I confirmed by experiments made on Extent of the”
ourselves, the faculty that man possesses of enduring expo- eR eel
sure to high temperatures, though but for a short time it is differs,
‘true. A comparison of these experiments with each other,
and with those of Sir Charles Blagden, taught us, that the
extent of this faculty might be very different is different in-
dividuals.
I. The experiments in which we exposed ourselves to the Dry heat borne
action of aqueous vapour enabled us to verify an observation ™°t easily.
of Dr. Fordyce, that the sensation of air loaded with va-
pour is much more painful than that of dry air at an equal
‘temperature.
4, We endeavoured to calculate with precision by weigh- Perspiration in
ing the effects of heat on perspiration. The loss of weight ae
we experienced in this way appeared to be in the direct ratio
_of the increase of temperature. We found too, that the
heat of aqueous vapour excited perspiration much more
powerfully than dry heat. 5.1]
Vou. XVII. Juny, 1807. Q
218 EFFECTS OF HEAT ON THE ANIMAL ECONOMY.
The faculty less 5. I think I have shewn, that the faculty possessed by
pa than man and animals of preserving a constant temperature,
: though exposed to great heat, is much less extensive than
has generally been supposed from the experiments made by
or than that of Drs. Fordyce and Blagden ; and that it is by no means com-
resisting cold. parable to the faculty they have of resisting cold, and pre-
serving a temperature superior to that of the t eakonaglites
medium. |
Whiat is its 6. Though this faculty is limited, it is nevertheless real:
mange ? it was an interesting inquiry therefore, to determine its
cause... Does it reside wholly in the perspiration produced
by evaporation, as some physiologists suppose? ‘The ex.
periments I have made render this opinion extremely proba~
ble, at least with respect to cold-blooded animals: but they
have not enabled me to decide, whether it be the same in
animals with warm blood. I have only found, that inani.
mate substances, the surfaces of which were entirely wet
and susceptible of evaporation, acquired a less elevated tem.
yperature, when exposed to a high heat, than warm-blooded
animals, under similar circumstances.
Less oxigen 7. | afterward endeavoured to ascertain the influence of
eceens ae heat on the phenomena of respiration. Dr. Crawford, who
‘thightempera- investigated this subject very minutely, imagined he observ
- ‘ed, that the vitiation of the air by breathing was propor.
tionally less, as the heat to which the animal was exposed
was greater. In a considerable number of experiments I
made, I was not able to discover any constant proportion
between the vitiation of the air in which animals were ine
tluded and the temperature to which they were exposed.
‘Podies dissect- 8- Lastly I turned my attention to the circumstances,
ed. that accompany death occasioned by exposure to heat ; and
I particularly examined the state of the bodies of animals
thus killed. The phenomena that appeared on dissection
however, among which the most remarkable was a great
Muscular irri- diminution of muscular irritability, were not sufficiently
Seb eh constant, to allow me to draw any conclusion respecting
: the cause of this death.
Observations
PREPARING ACETIC ETHER. B19
XIII.
Observations on the Two different Methods of preparing
Acetic Ether ; by Mr. Henry, Professor in the sal fs
Pharmacy at ‘Paris*.
Bere directed by the Society of Pharmacy to ascertain
the difference between acetic ether prepared in the direct
way, and that prepared by the intervention of sulphuric
acid, I shall proceed to give an account of the experiments
I made on the subject.
Mr. Gehlen, in a letter addressed to Mr. Guyton, in the Geblen says
79th Number of the Annales de Chimie, affirms, that he ce. Ga
has proved the truth of Scheele’s assertion, who says, without a mi-
acetic acid is incapable of forming ether, without the in- ee
tervention of a mineral acid.
The author does not say what acetic acid he employed ; But very little
he merely asserts the fact, recommends ‘ the use of very y sullices.
pure acetic acid,” and adds, “ that a minimum of sulphu-
rous acid is suithibiont to form ether.”
I know that ina great part of Germany acetic acid is The German
extracted from acetate of soda by means of sulphuric acid; etic ba
while that directed by Pelletier is obtained from acetate of acetate of soda.
copper. JI employed the latter, and it did not contain an
atom of mineral acid. But without entering into the dis-
cussion of a point long decided by uniform facts, I return
to the object of my inquiry, the examination of the two
kinds of acetic ether.
We are indebted to Pelletier for the process for obtain. Pelletier’s pro-
ing acetic ether, which consists in mixing equai parts of cen ba:
rectified alcohol and acetic acid; in cohobating the product
of the distillation on the residuum three times; and in
rectifying the ether from the potash.
I followed his process with this difference, that I carried
the cohobation as far as six times.
From a mixture of 500 grammes f{a little more than a Its results.
pint] of alcohol rectified to 36°, and an equal quantity of
“acetic ether at 11°, I obtained 495 grammes of ether at
* An. de Chim. Vol. LVIII. p. 199, May, 1806.
Q2 242
990 PREPARING ACETIC ETHER.
24°, immiscible with water, of a pleasant smell, and power-
fully reddening vegetable blues. No particular gas was
evolved during the operation; the atmospheric air alone
being displaced by the gasiform ether. I rectified this
ether over potash purified by alcohol; after which it no
longer reddened blue vegetable colours, indicated 25° by
the areometer, and weighed 420 grammes.
Durosier’s with The process by the intervention of sulphuric acid, Eine
sulphuric acid. ut by our colleague Durosier, consists in introducing
500 grammes of powdered acetate of copper into a tubu-
lated retort, and adapting to it a Woulfe’s apparatus.
. 500 Grammes each of. rectified alcohol and sulphuric acid
are then mixed together, and when cold are poured through
the tubulure into the retort; heat is gradually applied; and
640. grammes of acetic ether are immediately obtained,
mixed. with a small quantity of sulphurous acid. ‘This ether
marks on the areometer 254°, powerfully reddens vege-
table blues, and forms a precipitate with barytes or lime
water. During the process a small quantity of elastic fluid
is disengaged, which I found to be sulphurous acid gas.
Examination I rectified this ether with 50 grammes of potash purified
Mi at al by alcohol; and, to ascertain whether any sulphuric ether
ric ether. existed in it, 1 separated what came over into portions of
50 grammes each.
Gravity of the The first portion indicated on the areometer 31°, the
product differed 3 I A
atdifferent second 28°, the third 272°, the fourth 264°. These dif.
periods. ferent products together indicated 28°, and Nae 535
grammes.
Gravity of sul- To find whether it were easy to detect the presence of
Pees one: sulphuric ether in acetic ether by separating the products,
mixed near the I] made a mixture of 50 grammes of the former at 56°, the
ee thermometer being at 0, with 200 grammes of the latter at
25°. The two ethers thus mixed after two days standing
indicated 30°.
I distilled about 70 grammes of ether; it indicated 398, |
and had the smell of sulphuric ether very perceptibly ;
whence I concluded, that the mode I had employed was the
only one for separating the two ethers.
The two kinds [afterward subjected the acetic ethers to the following
eomipesse examination,
1. They
OXIDATIONS OF IRON. wat.
1. They were both of a pleasant smell.
2. Their specific gravity differed only four or five degrees,
3. They began to boil at nearly equal temperatures: the
first at 50° of Reaumur [1443° F.] the second at 46°
[1354°] making a difference of 4°, [9°.]
4. Exposed to-the air they evaporated slowly.
5. They were both equally soluble in eight parts and half
of water.
6. Sulphuric acid has very little action on these ethers;
it colours them slightly; and one part of ether and one of
acid, very completely mixed, evolve but little heat, about
30° [672°.]
7. Nitric acid at 46° is powerfully decomposed by these
ethers, a considerable quantity of nitrous gas is evolved,
and the residuum is oxalic acid.
From these different facts it follows, that the two ethers
are nearly the same, having only some shades of difference,
which do not affect their nature.
Thus the process proposed by Mr. Parmentier appears pre- The process
ferable to that of Mr. Pelletier, in being less expensive, re- eae
quiring a shorter time, and furnishing a larger quantity of Z
ether. But, while I give the preference to this process,
I am far from subscribing to the assertion of Mr. Geblen, but not essen-
that a mineral acid is necessary to the formation of acetic "*
ether.
XIV.
Inquiries concerning the Oxidations of Iron; by
Mr. Darso. *
Ir is ten years since ‘the celebrated chemist, Professor Proust supposes
Proust, struck with the two combinations that some metal. ™¢tals to com-
bine with oxi-
lic oxides form with acids, and reflecting on the two pro- gen in two fixed
portions of oxigen, that unmetallic combustibles usually cela
take, advanced the opinion, ‘* that metals combine with
oxigen only in two proportions :”? and though several che- Othersthe con. |
mists have since maintained, that there are intermediary "'Y-
* Journal de Physique, Vol. LXIII. p. 292. October, 1806.
oxides ;
922 OXIDATIONS OF IRON.
oxides ; and the author of Chemical Statics has gone still
farther, asserting, ‘‘ that the proportions of oxigen united
with metals vary, from the point at which the combination
is possible, to that in which it has attained its highest de-
gree;”? Prof. Proust has not considered the facts objected to
his doctrine as sufficient, and persists in the opinion, that
nature has fixed these two invariable terms of oxigenation.
Though I consider the subject somewhat differently from
the Madrid professor, I have a high opinion of his labours
and observations, and incline to think with him, not that
But wehave the proportions of oxigen are invariably determined by na-
“eeoearead su ture, but that most of the facts, on which the opinion of
cient accuracy r :
to determine intermediary oxidations are founded, have not all the accu.~
the question. yacy such a discussion requires.
Persuaded, that every research tending to elucidate this
point of theory cannot but be of great utility to the ad-
vancement of science,-I proposed to myself to make some
Iron well adapt- experiments on iron, as one of the metals best adapted ta
€c to the inves- such researches: and I shall relate them in the order I pur.
tigation, i
sued in my labours, persuaded, that I could not adopt a
better arrangement, than that of following the ideas that
suggested them. | .
New oxides The first means that occurred to me for discovering new
might be ob-
Sea by the oxides of iron were, Ist. to treat the red oxide with oxige.~
aid ot cisco: nizing. substances, confining the expansibility of the oxigen
sion, by compression. As experiments of this kind relative to the
carbonic-acid succecded so well with Sir James Hall, I had
or the electrics! 00 doubt of thus i increasing the oxigenation of iron. Qdly,
ari m. 40 subject iron wire to different discharges of electricity in
air containing more or less oxigen. Previously however I
was desirous of ascertaining how iron comports itself in
other modes of treatment, to which it has been already
subjected.
Oxides by Calcination. went
fron calcined I took one part of iron filings and three of nitrat of ‘pot.
with mitre, ash well powdered, mixed them, and threw them into a red.
much passed hot crucible, After keeping up the fire for three quarters
through the = of an hour, I withdrew. the crucible, and founda great part
ws stb of the potash and oxide of iron had passed through its. The
mixture
OXIDATIONS OF IRON. 993
mixture when cold exhibited a brown mass, with a few
green and iridescent spots.
This mass, pounded. and washed repeatedly with boiling The oxide
water, to divest it of its alkali, afforded me a brown pow- ste Poca
der, strongly attracted by the magnet, and not soluble insoluble * cald
cold miriatic acid. Heated with this acid diluted with a ™™tic acid.
little water, it afforded a colourless solution, from which
alkalis precipitated a blackish brown oxide, that did not Dissolved and
alter by exposure to the air, and at the expiration of a few eau
minutes, had acquired so great a cohesive force, as to he eae
insoluble in cold muriatic acid. When dried in the air it
was magnetic, and indeed retained the same characters as
before it was dissolved. * -
As the loss prevented my calculating the quantity of ox.
igen in this magnetic oxide, while its colour and magnetism
led me to conclude, that it contained less than the red, ob.
tained by calcining iron filings alone, I proposed to try this
method, seizing the moment when the magnetic oxide should
be formed. Accordingly I put into a crucible 100 grains
of iron filings, and after having kept them half an hour in Iron filings cal-
a brisk heat, stirring constantly, I withdrew them, and ‘imed alone,
found the weight 120 grains. I observed on this occasion,
that each grain of the filings, though covered with a stratum
of oxide, contained a metallic nucleus; and in order to ex,
pose the metal, and accelerate the operation, I triturated
these half oxided filings, before I put them again on the
fire. On continuing the calcination, and trying the oxide
occasionally with muriatic acid, I found the magnetic
_* JT fancied this at the time to be a peculiar oxide; but I afters
ward perceived, that its colour and magnetism arose from the con- Cause of the
centrated state of the solution and of the alkali with which I precipi- colour and
tated it; since if I diluted the alkali with water, or used lime, stron- sia. ah an
_ tian, or barytes water, the precipitates were entirely red,
On mixing green and red solutions of iron ina certain proportion
that may be found by trial, we likewise obtain black magnetic preci- Othe; magnetic
pitates, that do not change on exposure to the air: but the two phe- oxides.
nomena must not be confounded together, for there are magnetic |
oxides, that do not contain an atom of green oxide. The green
salts of iron too may be precipitated so as to be black, magnetic,
and unchangeable by the air. [ah
5 oxide
994 OXIDATIONS OF IRON.
Magnetic from oxide succeed the green, when the 100 grains had absorbed
"28 to 265 of ¢ P
oxeen. from a0 to a6 of oxigen.
This experiment, which [ repeated several times, always
afforded me the same results, except that sometimes I found
Sometimesa @ few hundredth parts of red or of green oxide. It is
wi red or, Obviously impossible however, from various circumstances,
ree oxide i
with it. that every particle of the iron should be equally exposed to
the action of the air and the caloric. .
‘Red and not On carrying the calcination so fair, that 100 grains had
yada with taken np 38 of oxigen, the precipitates were entirely red,
without exhibiting any trace of magnetic oxide. From
eae this term to:that- of 45 or 50 the oxigenation was very slow,
Ww ye : :
; and would have been impracticable without an increase of
but carried as heat: by raising the fire however, and renewing the air by
faras ‘36 nearly, : : ,
means of a pair of bellows, I carried the oxigenation as far
as 56. ‘This operation is very tedious and tiresome; butan
ap .aratus to save the trouble of renewing the air might ea-
sily be contrived, if the excess of oxigen were of any advan-
tage in physic or the arts.
All the oxides I treated this oxide at 56 with acids, and afterward pre-
aierthe itae? cipitated it by the alkalis and alkaline earths; 1 likewise
netic alike. ; i f
added to its solutions prussiates, gallates, and phosphates ;
to see if I could discover any properties distinguishing it
from the oxides that had preceded it. My trials however
were in vain, as I might have expected, since those at 38,
40, 45, and 48 had afforded me no characters to distinguish
them from one another.
Redness and The only difference I observed among these oxides was,
magnetism not . .
awit A oa that the red colour became more decided, and the magnetism
portion of weaker, in proportion as the oxidation advanced: but
Sa these properties depend more on the difference of the com-
pactness or density of the oxides, than on their preportion
of oxigen. *
ian ale This conformity of the properties of oxides, among which
o t : : ‘
ewiiie to aie the difference of the proportion of oxigenextends as far us 20,
ference of the or even 40 hundredths, as I shall show, proves the error of
oxide, a : Ate sme
requiring the formation of a difierent salt as characteristic
of each degree of oxigenation. Jn fact too extensive an
influence on the oxides of iron, and I believe on all the me-
* See the Note subjoined at the end of this Memoir.
tallic
r
OXIDATIONS OF 1RON. 225
tallic oxides, has been ascribed to oxigen. It has been sup-
posed, that all the properties of oxides of iron, both che-
mical and physical, are owing to oxigen; while on the con-
‘trary, from my observations I am induced to believe, that
its part is so passive, as to give it a claim to scarcely any of
| those properties.
Notwithstanding the uniformity of the circumstances, to Oxides variable
which I had subjected the iron in its different calcinations, ander similar
circumstances.
I observed, that, when 100 grains had taken up 28 of
oxigen, dhe oxide was sometimes entirely magnetic; while
at other times, having taken 30 or 32, it afforded a very
deep and extremely homogeneous green precipitate; and
lastly that at times the red oxide occurred by anticipation
at 28 or 30.. As I was prejudiced in favour of the less or Most pheno-
greater divisibility of substances, on which I believe most Mena depend
_ phenomena depend, I did not hesitate to ascribe to this Dili a ee
cause the results I had obtained: but to satisfy myself on stances.
this head, I took 300 grains of iron filings of three different Experiments
densities, and each portion less dense than that I had before With filings of
different denst-
employed. Let us suppose the ratio of their densities to ties.
have been at 1,2, 3. I subjected to calcination the 100
grains of the most dense, removing them from the fire every
ten minutes, to triturate them in a mortar. At the end of
half an hour, and having been triturated three times, they
had taken up 24.70 of oxigen, their colour was become al-
together red, their magnetism was very weak, and dissolved
in muriatic acid they aiforded red precipitates like oxide at
56. I repeated the same experiment on 100 grains of the
second degree of density, and when they had taken up 21
of oxigen, the oxide displayed the same properties as the
preceding. Finally I subjected to the same proof the last
100 grains, which were extremely fine, and which I had
previously sifted, that their density might be more uniform ;
but instead of taking them from the fire every ten minutes,
I triturated them every five, to diminish the action of the
oxigen as much as possible. In the space of a quarter of Oxides similar
an hour they had taken up 15 of exigen, and the properties
of the oxide were the same as those of the two preceding *.
Thus
* Sometimes they contain 2 or 3 per cent of green oxide, which
- isnot perceived, and which it is difficult to separate, even though
it
226
Red oxide with
18 of oxigen:
Proportion of
oxigen there-
tore variable.
Perhaps red
oxides with
6 or 8,
OXIDATIONS OF IRON.
Thus we have a red oxide of iron made in fifteen minutes,
which gives a fine blue with alkaline prussiates, is precipi.
tated black, or rather of a very deep blue, by galls, and is
not distinguishable from the oxide at 56, at least by any of
the means hitherto employed for this purpose.
All these facts prove the sagacity of the learned author
of the Statics, when he says, not from elective attractions,
but from the properties of oxigen and metals, that the pro-
portion of oxigen to metal may vary from the point at
which the combination is possible, to that in which it has
attained its highest degree, and that a multitude of circum.
stances may check or increase the proportion,
I did not carry this experiment. farther, but I conceive,
that by favouring the division of the iron by all possible
means, and at the same time opposing obstacles to the ac.
tion of the oxigen, we might obtain red oxides of iron with
_only 6 or 8 per cent of oxigen. And who knows whether
by preventing the action of this principle altogether, we
andironsoluble might not obtain powders of iron soluble without effer.
in acids with-
out being
oxided.
Other metals
the same.
To what are
the medical
virtues of these
oxides owing?
vescence in acids, and. enjoying the same properties as
oxides? For my part I am the more persuaded of it, as I
pay little regard to the principle generally received, that
metals must be previously combined with oxigen before they
will unite with acids: I consider the oxidation rather as a
consequence of the means we employ to divide the metals,
and reduce them to the degree of fineness required for their
solution in acids, than as an indispensable condition of
their solution. On this subject I intend to make some
researches, and I may then explain the motives that oblige
me to question this principle,
Before finishing my report concerning the oxides of iron
by calcination, I would wish to make one remark respect.
ing their most interesting application, their medicinal nse,
It is not yet known, whether these owe their virtues to the
iron or to the oxigen; and as the proportions of these in the
various preparations of this metal are undetermined, we are
wholly ignorant which deserves the preference: this theres,
fore is an objéct, that merits a careful investigation.
neans (To be continued, )
it is known to be present. Digestion for half an hour however i in
very dilute muriatic acid will dissolve it, or rather the iron it con:
tains, without attacking the red oxide,
: SC IENTIFIG
SCIENTIFIC NEWS. Q27
SCIENTIF IC NEWS.
Mr. Jessor’s Method of blasting Rocks.
Tue information respecting the blasting of rocks given
in our Journal, vol. IX. p. 230*, has not only been con-
veyed to France, but the process has been followed there,
and different experiments made on it. Mr. Baduel, an en- Rocks blasted
gineer employed in executing that part of the road from bean
Simplon, which extends along the south shore of the Lake
of Geneva, has availed himself of it on that occasion. He
used the common charge of powder there, which is sufficient
to fill one third of the hole, and at first filled the rest of the
hole with sand. This quantity of sand he diminished gradu-
ally, till he found, that two thirds as much as the powder
were sufficient. Hidix saw-dust, ashes, and other light Bran, saw-dust,
pulverulent substances, substituted instead of sand, pro- cts Se
duced the same effect. wise.
Several mines thus charged, and made with various de«
grees of inclination, in single blocks of stone, and knoity
trunks of trees, succeeded as completely, as if they had
been stemmed with the greatest care. But the success was Failed in the
not so uniform in the mass of the mountain itself, com- %°!'d rock of ike
posed of a blackish siliciferous limestone. In this case the morgen
explosion frequently took place without affecting the rock, '
though the hole was sometimes filled with gunpowder two
thirds, or even three fourths of its height +
These results are scarcely consistent with those obtained Succeeded
by Mr. de Candolle, in the works carrying on over i gaa ae
Cenis. This gentleman has seen the blasting with sand ex-
ecuted with success repeatedly, not in separate blocks, but
in immense rocks of a micaceous lime-stone schist. Some with a small
of these mines, charged with two ounces of powder only, case oe hye
produced as much effect as if they had had the usual charge,
which is double that quantity.
* See also, Vol. XII. p. 60.
+ The failure in these instances may obviously be ascribed to so
large a portion of the hole being filled with gunpowder, the sand
being forced through the remaining short space, before the resist-
ance offered by the solid rock could be overcome. ‘The next para-
1 is, W, N,
graph confirms this This
998 SCIENTIFIC NEWS.
AtPesey itsuc- This method has likewise been tried at the mines, of Pesey.
eke Bee tal On a separate block it was completely successful; but it
not in the solid was not so in the solid rock. Eight or ten holes 3 cent.
mek (11:8 lines) in diameter, and 3 or 4 dec. (12 or 15 inches)
deep, were bored at the same time in the vein itself. Some
were charged in the old method, others in the new, putting
into each the quantity of powder judged to be sufficient by
the workman himself and varying from 6 to 9 decigrammes
(2 to 3 oz). All the holes stemmed in the old way blew up
the rock; those covered with sand did not even split it.—
Some of the latter were charged in the same way with a
double or triple quantity of powder, so that it occupied
half or two thirds of the hole, the remainder being filled
with sand; and the explosion again took place without any
effect on the rock. The same holes, which had resisted this
double trial, being charged again in the old way with the
usual quantity of powder, produced a complete fracture.
Perhaps the ef- From these trials we should be led to conclude, that the
fe new process, though very good for blasting rocks, will not
always succeed, when applied to the solid rock of a moun.
tain, which generally presents itself bare but in part; and
still Jess in the interior parts of mines, where the points of
contact are more numerous. There seems to bea limit of
resistance, beyond which we cannot go by the new method,
as we may by the old.
An improve- Professor Pictet has proposed another improvement. It
eit Mr. is well known, that, in military operations, by making the
capacity of the chamber of the mine equal to four times
the bulk of the powder employed, a less concentrated ex-
plosion is produced, but more destructive at a distance, than
if the wadding were in contact with the powder itself.—
. Muskets too, and cannons are daily burst by leaving a space
between the powder and the wadding. Now in working
mines, this lateral explosion is exactly what is wanted as
Leaving a va- Strong as possible; it is probable therefore, that it might be
ees the obtained with less powder, by leaving an empty space be-
Great saving by tween the wadding and the powder. This method is said
a the to have saved several thousand crowns annually, by diminish-
; ing the consumption of powder to that amount, in themines
of the Hartz.
Mr.
- SCIENTIFIC NEWS. 229
Mr. Pietet accordingly recommends to those who are en-
gaged in mining a combination of the two methods; one of
_ which, the blasting with sand, would give security to the
_ Miners; the other, a partial vacuity, would save powder. His method.
‘This may easily be effected, by introducing into the hole, after
the powder, a cylinder or cartridge of paper, open at one
end, and with a small hole in the other, whichis to be placed
uppermost, to admit the priming straw. Over this the sand
may be poured in, and thus a vacuum of two or three
inches between it and the powder preserved.
Mr. Gillet-Laumont suggests another additional contriv- Gillet-Lau-
ance. He thinks, if the hole be vertical, or not much in- as
clined from this. direction, a more forcible concussion might
be given to the rock, by loading the sand with a heavy
weight. ‘To effect this he would introduce into the hole an A heavy weight
iron cylinder, with a lateral groove for the passage of the ae
straw, and surmounted by a heavy mass of iron, being a
continuation of the cylinder. This he supposes would add
greatly to the resistance; and the same piece of iron would
serve repeatedly for the same purpose, as it could not be
blown far, and therefore would easily be found.
EE
Extruct of a Letter from Mr. Gruen to J. C. Derame-
THERIE.*
SIR,
YOU are acquainted with the observations of Sir James
Hall on the effects of heat modified by compression +; but
Mr. Bucholz has just written to me, that powdered chalk
may be converted into a substance analogous to marble
without compression.
Wanting to prepare some quicklime, he put four pounds Chalk fused
‘and a half of pure washed chalk into a Hessian crucible, Hear mine
which he covered with a brick, and exposed it ina wind —
furnace for an hour to a bright red heat, not gradually
- raised. On examining the contents of the crucible, Mr.
* Journal de Physique, Vol. LXIII. p. 238, ait 1806.
+ See Journal, Vol. IX. p. 98; XIII. p. 328, 381; and XIV.
P- 13, 113, 196, 302, 314.
2 Bucholz
830 SCIENTIFIC NEWS.
Bucholz found it contracted one sixth. The chalk on the
surface and next the sides of the crucible was quicklime to
the depth of a line; but this was followed almost to the
centre by lamine adhering strongly to each other$ very
hard and solid, half fused, and of a yellowish white co-
lour, with a reddish tinge scarcely perceptible. Their hard-
mess was so. great, that here and there they would scratch
glass; and their softening, or incomplete fusion, which had
' taken place, was very evident, notwithstanding their lami-
nar form. Under this schistose mass was anather, extend-
ing to the bottom of the crucible, whieh bore still more de-
cided marks of fusion. It was broken into seven or eight
pieces, which exhibited a perfectly smooth, flattened, con-
choid fracture; were so hard in some parts on their edges,
as to cut glass, and so solid, as to require a pretty stout
stroke with a hammer to break them. Small fragments
were in some degree or even quite transparent.
Only one per On dissolving this fused chalk in muriatic acid, it lost
cent. of its acid 0.42 of carbonic acid, of which before it was heated it gave
Sadia out 0:43. The acid exhibited itself with all its character-
istic properties, and had not undergone the least alteration.
Magnetic iron | Mr. Bucholz has shewn too, that the magnetic iron stone
stone contain- of Suhl in Germany, is iron ata maximum of oxidation, or
ang red oxide. , é A - :
in the state of red oxide. This appears singular, as it has
hitherto been supposed,, that the magnetic property is con-
fined to the black oxide, and is destroyed by an excess of
oxigen; as it is according to Mr. Hatchett by an excess of
¢ sulphur and of carbon, and perhaps of phosphorus.
Volcanic cal- The same chemist has analysed the hyalite of Frankfort,
ae silex or volcanic calcedony, and found in it nothing but silex.
He had a loss however of 7 per cent. probably therefore it
contained also an alkali, which he was not able to examine
into, for want of a larger quantity.
Chromat of Mr. Klaproth has analysed a new fossil from Virieglach
aon. in Stiria, which afforded chromat of iron, mixed with a fo-
liated talc in curved laminz. I[t was tinged of a cochineal
red, and a peach-blossom colour by the chrome.
Flint of recent Mr. Haquet, of Cracow, the author of several geolo-
formation, —_ sical works in much esteem, has communicated to me a
memoir on the formation of gun flints, and the different
situations
-
SCIENTIFIC NEWs. 93h
situations in which they are found. He thinks them of very
recent origin, since they occur only in calcareous mountains
of secondary formation, and near their surface; and be.
sides he has found in these mountains petrified roots, wood,
and animal substances. In several fragments he has met
with rhomboidal crystals passing in gradation from carbon.
ate of lime to nearly pure silex.
You will find likewise in my journal a paper by Mr. Rit- Muriatic acid
ter, concerning the muriatic acid and soda formed by the 274 8°da form-
; ed by galvan-
two poles of the pile. He is pursuing his experiments on ism.
thissubject ; and Messrs. Berzelius and Hisinger are doing the
same, for they observed the formation of these in 1802,
_and consequently before Pacchiani.
See
Autographs from Stone Blocks. ss
A method of printing from designs made on stone was Printing from
mentioned in the last volume of our Journal, p. 158. paveerephs an
am informed, that the circular letters froma snuff manu-
factory at Offenbach to its correspondents, are printed in
this manner; and thata Mr. Reuter, a painter, of Berlin,
was the inventor.
=
Art of Swimming.
A society has been formed in Denmark for im proving and Swimming sb-
extending the knowledge of the art of swimming; an art mre ae, Den-
certainly of great utility with respect to health, cleanliness,
and safety, and particularly valuable to a maritime nation,
ee
Description and Chart of the Faro Islands.
Mr. Lorvenorrn, a distinguished officer in the Danish Chart and a
navy, has lately published a new chart of the Faro islands. abet sige
A particular and interesting description of this little known
portion of the Danish dominions is given with it.
Scientifie
232
Scientific ex-
pedition from
Russia.
Application of
electricity to
discharge can-
nom,
Premium for
the improve-
ment of alegar.
it has hitherto received.
SCIENTIFIC NEWS.
Scientific Voyage.
AN expedition has been fitted out from Kamtschatka to
the Curile and Aleutian islands, and the North West coast
of America, the objects of which are entirely scientific.
Mr. Redowski, who accompanied the embassy from the
court of Russia to Pekin, as botanist, is placed at the head
of it. An astronomer will sail with him for the purpose of
making observations, but his name is not mentioned, or that
of any other man of science. The voyage is to be of three
years duration.
TE
Rockets discharged by Electricity.
THE 14th of February, at two o’clock in the afternoon,
M. Bouche made an experiment in the Jardin des Plantes
at Paris, to try the effect of electricity applied to gun bat-
teries. Instead of guns he had fixed about one hundred
rockets on long sticks, disposed in the garden. The rockets
were all connected by an iron wire, and the same spark
caused them all to explode at the very same instant. The
concourse of people was very great, the weather being re-
markably fine. This new invention is not intended to in-
crease the destructive powers of those formidable weapons ;
but it is expected to afford the means of using them without
exposing gunners to the fire of the enemy.
—— TEE
Imperfections of Alegar.
VINEGAR made of beer, properly called alegar, con-
stantly retains a mucous matter, which prevents it from
keeping. The society of amateurs of sciences and arts at
Lisle, wish to have this defect removed; and propose a
medal for the best mode of improving alegar in those qua-
lities which may render it equal, or nearly so, to the best
wine vinegar. It deserves notice, that this liquor has some
properties, which, could they be separated from others not
so valuable, would render it worthy of more attention than
j :
JOURNAL
OF
»- NATURAL PHILOSOPHY, CHEMISTRY,
AND
THE <-ARTS.
AUGUST, 1807.
ARTICLE I.
A Memoir on two new Classes of Galvanic Conductors. By
Mr. Erman*,
Tue faculty of propagating or isolating electric effects, Galvanism has
exhibited in such different and variable degrees by different apse Le
substances, eminently demands our attention, because the ciectricity,
time is arrived for comparing this faculty with the chemical oe
constitution of bodies, to establish something respecting the perties of vas
nature of the electric fluid. The anomalies of the conducta ducting sub-
. a ° ei) stanceés.
ing faculty are so strongly marked in galvanic electricity,
that they have afforded arguments to those, who refer the
phenomena of this class to a principle essentially different
_ from electricity.
The examination to which I have subjected a great num-= New experi-
ber of substances, with respect to the phenomena they pre- san r gerry
sent, when they are employed to complete the galvanic cir- arguments,
cuit from one pole of the pile to the other, has furnished
* Journal de Physique, Vol. LXIV. p. 121. Feb. 1807,
To this Memoir the French National Institute awarded the Prize of
$000 fr. [£125], founded by the Emperor, to be given annually to the
best paper on the subject of Galvanism, till a discovery on its principle
or application shall be made, of sufficient importance to merit the sum
of 60,000 fr. [£2500], of which this is the interest.
. Vou. XVIL—Aveust, 1807. R me
2) RR ee ae ee ore
:
234
and lead toa
new arrange.
ment of con-
ductors.
1. Perfect non-
conductors.
2. Perfect con-
ductors.
3. Imperfect
conductors.
NEW CLASSES OF GALVANIC CONDUCTORS.
me with answers to some of these arguments: but I have —
obtained.a result of much more importance, stnce I have
convinced myself by authentic facts, that in effects of this
kind every possible combination is realized; for, if any sub-
stance be applied to the two poles of the pile, one of the
five following effects will take place.
1. Either this substance, not acting separately on either
of the two poles, leaves them perfectly insulated, when we
attempt to set them im action by its intervention. The re-
sult of this perfect insulation is, that the galvanic circuit ‘is
not completed ; and-that the electric tension remains at its
natural maximum at each pole, without our being able to
modify it by the interposition of the substance employed.
Perfect nonconductors are cold glass, oils, and resins, in
every state of aggregation ; water, when solid or in vapour;
&e. ’
2. Or the two poles exert, through the mtervention of the
substance applied, a reciprocal action so intimate, that, per-
perfectly neutralizing each other, every phenomenon pecu-
liar to each ceases, so that it is Impossible to act in a dis-
tinct and appreciable manner on either of them. Perfect
conductors are all metals without exception, and in the fame
degree, at least as far as we know: for it must be observed,
that it is only from analogy we ascribe this property to those
that have not actually been subjected to expermment ; and it
is possible, that some metal may have exclusive properties
with respect to galvanism, analogous perhaps to those of
magnetism and iron. The possibility of this, and the great
importance of the discovery, demand a series of experiments,
from which we ought not to be deterred by the little proba- -
bility there is of success,
3. Or the substance applied to the two poles permits their
reciprocal action, and completes the galvanic circuit, but in
such an imperfect manner, that the distinct effect of each
pole will continue to manifest itself, and that it will be pos-
sible, by the intervention of the substance applied, to in-
fiuence each pole separately, according as we act on one
extremity of the imperfect conductor or on the other. This
property, which IT have demonstrated in moist conductors,
and in water itself, is so much the more important to be
studied,
NEW CLASSES OF GALVANIC CONDUCTORS. 935
studied, as it is connected with chemical and physiologiéal
phenomena. In. fact, except in the case of sparks alone,
there is no decomposition that takes place but in conductors
of this class; and all the parts of organized bodies, that
galvanic electricity is capable of modifying, equally belong
to it.
4. Or the given substance, acting as a perfect conductor 4. Positive con-
when applied separately to either of the two poles, is found ductors.
nevertheless to beiong exclusively to the positive pole, as
soon as it is applied to both at once to complete the galvanic
circuit. Conductors of this kind do not close the circle *
completely from their insulating the negative effect; and if
the contact of the two poles by their interposition, we can
neither charge the positive, nor discharge the negative
pole.
. . Or lastly, the effect mentioned in the preceding para- 5. Negative
graph is inverted, that is to say, the substance, that acts on conductors.
either pole separately as a perfect conductor; belongs en
tirely to the negative pole, as soon as it is applied simul-
taneously to the two extremities of the pile. Hence resujts
a maximum of electric tension in the positive pole, and the
impossibility of producing any divergence at the negative
side by the intervention of substauces of this class.
The phenomena of the first.and second class have been Phenomena of
known too long to excite our attention, though they furnish Se pia
many interesting particulars. Those of the third I suppose Knowl.
_ to be equally known; and therefore I shall confine myself
to the facts, that demonstrate the existence of conductors
of the fourth and fifth classes. These facts, beside their
novelty, afford some interesting problems to be solved, and
new views to be pursued in galvanic researches,
Before I-proceed to the new facts I have to offer, I shall Must be exa-
mined by the
3 . electrometer
themselves with clearness, and in their whole connexion, but alone.
as far as they are studied with the assistance of the electro-
meter alone applied directly to each pole; and without hay- Inconvenien-
ing recourse to the condenser, the employment of which ir aga Fou
_ being always interrupted, and its language frequently equi- — uh
vocal, sometimes even deceitful, it fetters the progress of
the observation, and never allows us to take it in at one view
$ Rg : all
observe, that the phenomena in question do not exhibit
236
The gold leaf
electrometer
very convenie
ent.
The apparatus
must be per-
fectly insulat-
ed.
Glass not suffi-
cient.
Particular at-
tention to the
electrometer
necessary.
NEW CLASSES OF GALVANIC CONDUCTORS.
all the changes, that characterise each state of the pile. In
the nice experiments I have to relate, it will be seen, that
the number of simultaneous observations to be made would
render the use of the condenser extremely inconvenient :
and if the modifications necessarily produced at each pole
by the augmentation of the electric capacity, that results
from the very application of the condenser, be considered,
the reason of my excluding it will be obvious. Gold leaf
electrometers, applied immediately to the poles, and to the
the subjects of the experiments, are free from every incon=
venience; and if they be ever so little sensible, they indicate
with extreme fidelity and promptness the progress and de-
gree of the most complicated modifications, that the pile un-
dergoes.
Another essential condition to the success of the investi-
gation is, that the pile and all parts of the apparatus be per=
fectly imsulated. I have found no mode of insulating the pile
better than to fix it in the centre of a large cake of resin,
taking care not to render the cake an electrophorus by any
accidental friction. As to the other parts of the apparatus,
we should never trust to the insulating power of glass alone;
and in applying a resinous coating to the surfaces, 1 have
found the dry way far preferable to the moist. Lastly, be-
fore commencing the experiments, and during their course,
it is proper to try by means that may readily be contrived
and varied, whether all parts of the apparatus completely
insulate the electric effects: and it is particularly impor-
tant, to pay this attention to the electrometers, to be certain
whether the glass of these instruments, which cannot be
coated with resin, preserve itself constantly m a perfectly in-
sulating state. I know by experience, that the progress of
the observations is frequently confused, from the surface of
the electrometer having imperceptibly become a conductor.
This inconvenience is remedied by drying the instrument,
and not by exhausting it, for fear of falling into a still worse
inconvenience, the communicating to the glass an electric
charge.
Sect.
NEW CLASSES OF GALVANIC CONDUCTORS, 937
Secr. I.
Of Conductors, that,.in establishing a Contact between the
two Poles, insulate the negative effect, while they continue
to propagate the positive Electricity.
When we apply separately to each of the poles of the Flame a per-
pile the flame of a spirit lamp, it acts as a perfect conduc- Pic ees!
tor: but if it be applied simultaneously to both poles, it separately, but
completely insulates the negative effect, while it continues pet fem
to conduct the positive electricity with the same energy; and tricity when
in consequence of this partial insulation, the electric circuit a et both
is not completely established.
The faculty that flame possesses of conducting the fluid Its conducting
of the pile, which has been so much disputed, is placed be- Powerdisputed
yond doubt by the following facts.
To eitherof the poles of a perfectly insulated pile of a Facts that
hundred pair of plates, more or less, apply a very sensible PTOv?
gold leaf electrometer, which will presently acquire the de- Electricity
: . ., communicated
gree of divergence corresponding to the energy of the pile, p, flame to ei-
and the more or less perfect insulation of the opposite ex- ther pole.
tremity by the circumambient air, As soon as the diver-
gence of the instrument is become stationary, present to the
metallic wire of the opposite pole the flame of a spirit lamp
completely insulated ; and the divergence of the electrome-
ter will not be increased. But the moment a communica-
tion.is established between the flame and the ground, by in-
troducing into it a wire not insulated, the electrometer will
diverge as much as if a communication had been established
between the opposite pole and the ground, by means of an
uninterrupted metallic conductor. This effect is the same
at the negative as at the positive pole, a circumstance which
will appear by and by of importance. Electricity therefore
may be communicated to either of the two poles of the pile
by the medium of the flame of spirit of wine.
In the same manner it may be radically abstracted from Abstracted by
either of them, Let each pole communicate with an elec- priesiy a se sd
trometer by means of a wire. If an insulated flame touch _ na,
either of these wires, the corresponding electrometer will
oy lose
Both effects
may be shown
at once by two
flames.
Farther proo‘’s
of the conduct-
ing power of
flame.
Flame there-
fore does not
insulate galva- .
nism, and con-
uct electricity
,
Its conducting °
power isiferior
to that of me-
tals,
NEW CLASSES OF GALVANIC CONDUCTORS.
lose nothing of its divergence; but it will be completely des
prived of it, the moment a divect communication between
the ground and the flame is established.
AER o effects may be seen at once acting i im combina-
tion, by preparing two perfectly imsulated flames, and guid-
ing into each one of the wires proceeding from the two ex-
trentities of the pile. If the insulation be perfect in all
points, both the electrometers will indicate after a few se-
conds the same state of divergence, as if the poles were not in
contact with the flame. Now if one of the flames be made to
communicate with the ground, the electrometer of that pole
will immediately lose all its divergence, and the divergence
of the electrometer of the other pole will be a maximum.
The alternate contact of the two flames therefore produces
the same effect, as if we had immediately touched the extre-
mities of the pile itself. :
Lastly, that we may be fully convinced of flame being
an excellent conductor for all the effects of the pile, that de
not depend on the closing of the cirele, the following facts
should be noticed.
- Bend the wire on the top of the electrometer, so that the
point shall terminate in an insulated flame. Into the same
flame insert a wire from one of the poles. If now the oppo-
site pole be touched, the electrometer will receive a maxi-
mum of divergence corresponding to the case. “If afterward
the electrometer itself be touched, the pole with which it
communicates through the medium of the flame will be dis-
charged, Lastly, by touching the flame, we shall discharge
at once both’ the clectrometer AF this pole, and ‘the electro-
meter communicating with the fiame. i!
These facts prove to a demonstration, that the flame is far
from insulating the electric effects of the pile in the cases
indicated. ‘ They show, that with respect to these cases there
is no ground for admitting a galvanic fluid, which the flame
insulates,in opposition to the electri ic fluid, of which it serves
as a conductor.’
In the following fact, however, we find an anomaly, which
shows us, that the conducting power of the flame, however
perfect it has appeared to us m the preceding experiments,
is nevertheless very inferior to that of metals, when thesé
; twa
ee as ae
= y
NEW CLASSES OF GALVANIC CONDUCFORS. 239
two kinds of conductors act in opposite directions. If one
of the poles communicate with an electrometer by means of
a wire, an uninsulated flame, brought into contact with this
wire, will take from it, as has been seen, all the divergence
before imparted to the electrometer by the transient contact
of the opposite pole. But if a permanext metallic commu-
nication be established between this pole and the ground,
the electrometer will reach the maximum of divergence, and
remain at it without any diminution, though the uninsulated
flame continue to touch the wire, by means of which the
electrometer is in communication with the pile. It is to be
observed, that this effect is precisely the same at both poles.
- But how different would be the action of a metallic con-
ductor, if in this experiment it were substituted instead of
the flame! It is well known, that the application of unin-
-sulated metal would prevent any intensity of electricity pro-
ducing divergence ; and that the application of a humid con-
ductor would at least diminish it extremely, if it did not
reduce it to nothing. Flame therefore, which has: hitherto
beey considered as a good conductor, dees not here produce
' the effect, that was te be expected from it.
~ But this anomaly is of little importance, compared with It conducts po-
that which flame exhibits, when it is applied simultaneously oe
‘ i j 3 ” city, and insu-
to both poles, with a view to close by its means the galvanic ks negative,
cirele.. The following facts prove, that in this case it be- at the same
; : Bs time,
longs entirely to the positive pole, and absolutely insulates
all the negative effects, which has led me to place it in a
~ Separate class.
Let each pele of a well insulated pile, consisting of about Experiment ia
a hundred and fifty pair of plates of silver and zine, be con- which it ap-
é ‘ ; zs pears a non-
nected with a sensible electrometer... With each pole con- gyctor,
néct a wire, supported by a completely insulating;stand; and
let the extremities of the wires be brought so near together,
that one flame may be in contact with both. On an insulat-
ing stand place a spirit lamp, and commence the experiment
by bringing the flame into contact with the two, metallic
-wires. As long as the flame remains insulated, the.electro-
meters of both poles will diverge nearly as if the two. polar
wires were perfectly insulated. After some time, indeed,
the electrometer of the negative pole will exhibit a little
c- . stronger
240
Proof that it
conducts posi-
tive electricity.
This farther
confirmed by
experiments.
NEW CLASSES OF GALVANIC CONDUCTORS,
stronger divergence than that of the positive, though: every
thing else will appear to indicate an absolute insulation; for
if a communication be established between either of the
poles and the ground, its electrometer will lose all its diver-
gence, and that of the opposite pole will attain its maximum ;
and on touching both poles at the same time, as strong a
shock will be received, as if the two poles were insulated. by
a stratum of air, It appears, that hitherto philosophers
have contented themselves with this single experiment, to
affirm that flame insulates all galvanic offceer ; but the fol-
lowing facts prove, that this insulation is partial, and that
flame continues to be an excellent conductor for the positive
pole.
Every thing remaining as in the preceding experiment, let
a communication be made between the flame and its sup-
port; or, which is more simple, touch the flame itself with
an uninsulated metallic rod. Immediately all the diver-
gence passes to the negative pole, and the positive is abso-
lutely discharged. If the strongest divergence possible have
been previously given to the negative electrometer, by touch-
ing the opposite pole, no application of a good conductor to
the flame will take off the least part of this negative diver-
gence; while the same application will instantly destroy
every vestige of divergence before imparted to the positive
pole, and transfer-it to the negative side in the strongest “ag
gree possible.
Whatever extent be given to the flame, and however near
to the negative wire it be touched, it still remains impossi-
ble to act through its medium on the negative side, so as to
take away the divergence. Flame belongs wholly therefore
to the positive pole, since by touching it this pole is imme~
diately discharged, and the negative pole is mediately
brought to a maximum of divergence.
This paradoxical property is’ confirmed by the following
experiments. The two polar wires being united in the same
insulated flame, immerse in this flame the hook. ofa: sensi-
ble electrometer, and it will acquire a weak positive diver-
gence, if the two poles had not previously arrived at an
equilibrium of intensity. But this positive divergence at~
tains its maximum, the moment the negative ‘pole is made
to
NEW CLASSES OF GALVANIC CONDUCTORS. Q4i
to communicate with the ground. If we afterward touch
the positive pole, the electrometer immersed in the flame
mamediately loses all its divergence. Lastly, if a communi-
cation be established between the ground and the flame it-
self, both the electrometer in contact with it, and that ap-
plied to the positive pole, are discharged, while that on the
negative side attains the highest degree of divergence. These
effects are completely explicable, on the supposition that the
negative pole is insulated in the flame, while to the positive
it is a conductor.
What renders this absolute insulation of the negative pole Flame gives
by a conducting substance still more paradoxical is the °¥t positive
ls 85 é iL A/a 3 electricity toa
very intimate relation the flame bears to positive electricity. distance of 12
In fact, to take from this pole the divergenee that has been % 2 feet per-
given to it, it is not necessary actually to touch the flame; ae gles i
it is sufficient to bring over it, at the distance of a foot and
half, or even two fect, a metallic conductor communi-
_ eating with the ground; when the positive electrometer will
immediately arrive at zero, and that of the negative at the
maximum of electric intensity. In hke manner an electro-
meter, the hook of which is held at a similar distance above
the flame in which the two polar wires of a powerful pile
terminate, will very readily become charged with positive
electricity, when a communication is made between the
ground and the negative side, and will be discharged on
touching either the flame, or the pole of which that flame so
eminently propagates the effect. This action of the flame and toa few
extends laterally also, but by no means with equal energy, aa
for in this direction it is confined to a few inches.
_ All the indications by the electrometer, that have been Flame does
related, prove, that the galvanic circle is not completed by ie pea ag
the intervention of the flame; and experience long ago circle,
showed, that the decomposition of water did not take place,
_.and the physiological effects of the pile were not manifested,
when the exciting are was interrupted by the interposition of
flame. Reflecting, however, on the faculty flame has .of yet momen-
conducting the electricity of each pole separately, and insu- @'Y effects on
Sind ; : 4 the nerves may
lating only the negative effect, it appeared to me) possible, be produced
to obtain some momentary effects on animals, by discharging 'hroush +t.
at once into the ground the two poles united by the flame,
and
242 NEW CLASSES OF GALVANIC CONDUCTORS.
and placing very irritable organs in the way of the discharge,
a at- After several fruitless attempts; I arrived at’ the following
vain. combination, the success of which has never since disap-
pointed me, and perhaps furnishes an interesting datum for
the general theory of the electric charge. ree
Successful ex- Let a powerful pile be perfectly insulated, and its two
ee flames be united in one insulated as perfectly. Prepare as
speedily as possible the hinder extremities of a frog, so that
the ischiatic nerves shall be disengaged from the Heth, and.
from the spine, the lumbar vertebra of which are removed.
Place the muscles on the alg pole of the pile, letting
the nerves hang down freely ; and, holding an exciting are
by a completely insulating handle, apply one extremity to
the flame, and the other to the nerves. By this no contrac-
Cautions. tion will be occasioned: or should there by chance be some
traces of contraction, as in fact has occurred to ine, though
very rarely, these must be considered as exceptions pro-
duced either by the defective insulation “of the handle, ‘a
mere mechanical irritation of the very susceptible nerves, or
by the action of the atmospheres of the poles; for I have
found in another series of experiments, that every pole,
charged by the contact of the opposite pole, becomes ‘tlie
centre of a sphere of activity, in which the capacity of sub-
stances is powerfully modified without contact, and i
_ by the mechanism of electric influences.
This may ac- [am tempted to explain by the last mentioned property
spud setiia those sparks, which observers of credit affirm they have ob-
obtained by tained by the contact of a single pole, when the pile con-
ae sisting of a thousand pairs possessed very great energy: and —
J conceive, that the contractions sometimes seen in the case
in question result from the weak positive electrisation, which
the negative pole produces by its influence’ on ‘the exciting
are, so that the equilibrium is restored not between the po-
“sitive and negative poles, to which the flaine’ presevts an in-
surmountable obstacle, but between the negative pole and
the anterior part of the insulated arc, become positive by
influence, It is’ obvious, that the effect of this restoration
of equilibrium must be-of infinitely small intensity ; ‘and
that, to produce the Weakest contractions, it supposes an ex-
traordinary degree of exvitability,
Be
NEW CLASSES OF GALVANIC CONDUCTORS.
24S
-Be this as it may, to prevent any mistake from creeping in, Farther pre-
if the contact of the insulated conductor, which terminates
at oné extremity in the flame, and at the other at the nerves,
produce a contraction during the period of the highest. irri-
tabilitv, a few moments snantd be suffered to ate the
application of the insulated exciter should be repeated from
time to time, and very soon the application will produce no
effect. The experiment then properly commences. Tn fact,
when the insulated exciter has no physiological action, it is
sufficient to establish a communication between it and the
ground, either by touching it with the finger, or taking it
in the hand without the thstlatine handle, and very strong
contractions will be produced every time the circuit is come
pleted from the flame to the nerves. “The influence. of the
ground may be proved, by, completing the circuit with an
- Msulated and an uninsulated arc alter nately. Ifa certain
interval be allowed between these comparative applications,
| those with the insulated are will never produce any effect,
those with the uninsulated will coustantly excite contractions.
_ J must observe, however, that this kind of galvanic excite-
ment, by the intervention of fiame and the ground, requires
a much greater excitability in the subject, than the common
. method of completing the circuit immediately from pole to
pole; for the muscles are obedient to the latter, long after
| they have ceased to contract by the application of an un-
: insulated conductor to the flame. It is to be understood,
~ however, that, if the prepared muscles be placed on the po-
“sitive pole, and the circuit teh be completed from the
k flame to the nerves, no effect will be obtained, whether the
are be insulated or uninsulated; for, as the flame belongs
exclusively to the positive pole, it is obvious, that it cannot
‘ podice contractions with the pole of its own nature.
7
pespetiee, effect, and consequently cannot compete the gal-
yanic circuit, But in the application of the uninsulated are
between the flame and the nerves, it is properly the ground
that serves as an intermediate chain, and the mind may dis-
tin wish three different effects at the same instant of time,
‘The first is that of charging the negative pole to a maximum
. Oa at
ose
cautions.
» Experiment.
The irritability
of the subject
must be great.
When placed
on the nega-
tive pole, no
effect is pro-
duced,
¢
‘The explanation of this fact appears to me to arise na- The fact ex-
Bacaty from what has been said.- The flame insulates al] Plaized.
G44, NEW CLASSES OF GALVANIC CONDUCTORS.
at the expense of the ground: the second, the returning
into the ground all the excess; by which the positive would
arrive at a maximum of intensity, were there not a want of
insulation: and from this want of insulation results, as a
third effect, the momentary discharge of the two poles inte
the ground. It may be conceived, that very irritable or-
gans, serving as a vehicle to this process, will experience that
kind of shock, which accompanies the prompt restitutions
of the electric equilibrium. If my object were at the pre-
sent moment to display a theory of the electric charge, I
certainly should not content myself with these germes of
ideas, which however appear to me fertile in their conse-
quences. It may be presumed too, that this kind of exci-
tation, in which the ground at large concurs, must require
a much greater degree of irritability, than these im which
the equilibrium is established immediately from one pole to -
Theanthor the other. Whether the impossibility of obtaining chemical
could never decompositions by the intervention of flame depend on this
obtain any che-* . ; ae
mical decom. Circumstance, I cannot say ; or even whether the impossibi-
positions in ity be absolute: all I knew is, that I have never produced ©
arto any such effect, notwithstanding the numerous combinations
I have tried.
Inthis casetoo When the insulating power, which has been so perempto-
re pean rily ascribed to flame, be considered, the following observa-
* tion will appear interesting. ‘To produce the contractions
just mentioned, it is not necessary, that the uninsulated ex-
citing arc should immediately touch the flame, as it: may be
held several inches above it. I have sometimes succeeded
in producing contractions, when it has been held a foot and |
half above it, particularly when I have armed this extre-
mity of the are with a metallic disc a few inchesiin diame~ |
ter, in order to bring it into mere intimate contact with, the —
hot air issuing from the flame, and serving as a conductor
to the positive electricity. '
The exciting I shall just. mention here another observation, whichs I 4
arc retains its have repeated several times, but the particulars of which I
Bae mom am far from having sufficiently studied... When the exciting f
arc, brought into communication with the ground, has pro-’
duced a contraction, by being placed sinnitizowecatslys in con=
tact with the flame and nerves, it will retaim this property for
about |)
5
44
fu
NEW CLASSES OF GALVANIC CONDUCTORS. 245
about twenty seconds, without its being necessary to keep it
insulated during this time. In this state it produces a fresh
contraction on touching the nerves-alone, without requiring
the flame to touch the other extremity. This observation
has nothing in it of novelty, as there are many analogous
facts: yet it is in some degree interesting, as it facilitates
our varying the modes of experimenting. But what induced
me to mention it here was, that the success of the experi-
ments, in which an insulated and an uninsulated arc are al-
ternately employed, depends on this circumstance; and for
- this reason, in describing these experiments, I mentioned
the necessity of allowing a certain time to elapse between
each of these comparative applications.
The facts I have recited incontrovertibly prove, that the Flame of alco.
flame of spirit of wine is an excellent conductor for either hel thusshown
; y : . to bean excel-
pole of the pile; but that in connecting the two poles it jent conductor
completely insulates the negative side, while it continues to of either em
be eminently conducting for the positive. But the problem Naa pias di
is still far from being solved: it remains to be known, what the negative _
: : : ; Rt when employ-
as the mechanism of the action, on which this singular pro- ed to complete
perty depends. It would certainly be rash to determine any the circuit.
thing respecting facts so new, and deviating so widely from
_all known analogy: I only mention the following hypothesis,
therefore, on account of the interesting facts of which I
have obtained a knowledge, taking it as a text for farther
researches.
I had long imagined, that the electric intensity manifested ,,_,. cogieas:
exclusively at the negative pole by the intervention of the ed in some in-
flame might depend on the two opposite properties assigned ete con
to it, and in fact distinguished in certain phenomena of ty: inothers te
common electricity. We conceive we have equally reason Set i
to say, that flame dissipates and destroys all electricity, as
_ for instance, when charged plates of glass or resin are pre-
sented to it; aud that in other cases it collects electricity, as
when it is applied to the summit of electrometrical points
intended for meteorological observations. I thought, there-
fore, that something analogous took place here: but the
_ dispersive effect being much superior, the positive pole was
_ constantly discharged by drawing off the excess of the elec-
tive fluid, while by this very act the negative side was left
; at
246 NEW CLASSES OF GALVANIC CONDUCTORS.
(
But this hypo- at a maximum of intensity. But amore accurate analysis of
thesis will not f : 4 ,
ariply here: the phenomena, and a farther investigation of the facts that
occurred, convinced me of the erroneousness of this hypo-
thesis: for if it were by a simple dissipation of the electric
fluid, that flame destroys the intensity at the positive pole,
and carries it to a maximum at the negative, it must be per-
fectly indifferent, whether the flame were insulated or not.
Solids produce Now we have seen, that this is not the case. Besides, it
similar pheno- ll _ RL ahae 1 se ik iM
ee will appear, that solid substauces produce analogous pheno-
mena, though inversely : so that here we have no expansible
and flames fluid to dissipate or accumulate the electric. But what de-
from different my onstratively proves the falsity of the hypothesis is the
substances dif- i d é . ; ps
fer in their ac- total difference, that exists in the mode of action of different
UsE. flames, according to the chemical constitution of the bodies
from which they emanate. :
Flame not a It is a singular abuse of the abstract signs of language,
distinct sub-
stance always tO speak of flame as one constant homogeneous substance,
ofone nature. whatever be the the nature of the matter undergcing igni-
tion. This errour might have been pardonable previous to
Electricity and the discoveries of pneumatic chemistry, particularly with
sg aE ” respect to common electricity, the chemical effects of which
mode of ope- are nothing, or difficult to ascertain. In galvanism, on the
eae contrary, the chemical efiects stand foremost: every physical
effect is preceded or accompanied by chemical action; and it
is precisely from this, that the discovery of Volta will for
ever remain a memorable epoch in the annals of science.
His pile is a landmark erected on the common irontier of
chemistry and natural philosopby.. A comparison of the
mode of action of the flame of different combustibles soon
decided the fate of my hypothesis.
Flame from, _ All flames arising from the incandescence of substances
hidrogen and
carbon produc-
es the preced- of insulating the negative pole, and acting as conductors to
ang elicets. ia positive, in the same degree. Those, on the contrary,
chase of sul- that contain neither hidrogen nor carbon, either do not pro-
phura com- i! . ; ‘
Bite noncon- duce this effect ; as sulphur, the flame of which equally in=
ductor. sulates both poles: or produce an effect totally opposite; as
Flame of phos- phosphorus, which, in a state of ignition, insulates the posi-
phorus insu- tive, and conducts the negative. Ishall enter a little into
lates the posi- : ‘
tive pole only, the detail of these facts.
containing hidrogen and carbon produce the phenomena
-
Ow
NEW CLASSES OF GALYANIC CONDUCTORS. 947
On uniting the wires of the two poles with the flame of, a Flame of vart
ous substances,
wax or ts candle, an oil lamp, yellow amber, camphor,
volatile oils, and several other hidrocarburetted substances,
the effects I have described, taking for example the fiame
of alcohol, will, be observed fully. I had a strong reason,
however, for proposing the latter, since the combustion of
the substances here mentioned is scarcely commenced under Soon produced
the influence of the galvanic poles, before a fuliginous de- beers oe
position takes place on each of the wires, particularly on
that of the negative pole. This deposition is distinguished especially on
by a kind of dendritic vegetation, very striking on. the ne- ae Riean
gative wire, but much less distinct, and sometimes not to ;
be perceived on the positive. These ramifications increase that stretched
and spread with great rapidity, particularly at the negative a eee
pole: they tend toward one another from the negative to the
positive, and the moment when these fuliginous filaments fill
the space between the two wires, all electroscopic effect ceases,
the circuit beimg closed by the conducting power of the car~
bon. The flame of spirit of wine, or a; naphtha, is free Alcohol and
from this inconvenience. If the experimenter would ob- Teed
serve these fuliginous vegetations in the greatest energy, he
Oil of turpen-
should burn in a small ee aenle oil of turpentine rectified by tine has emi
distillation. On bringing into this flame the two wires of a uenty,
galvanic pile of tolerable strength, the fuliginous vegeta-
tions will be produced in such abundance, that frequently
they will be seen to rise from the edge of the capsule, and ste Pei
form by their ramifications a very pleasing crown, the incan- pleasing exhi-
descent points of the tufts having a very rapid movement of bition.
tension on the fuliginous Selig that supports them.
To obtain the partial insulation of the negative effect, it.Carbon not ne-
is not necessary, that the substance from which the flame “?'Y:
emanates should contain carbon, I filled my gazometer yidrogenalone
with very pure hidrogen gas, carefully washed ; read the sufficient.
flame of a stream scant gas perfectly insulated between
_ the two wires of a pile; and observed, that the effects dur-
i ing the whole course of the experiment were perfectly iden~
_ tical with those which I have described above with the flame
of alcohol,
As to the flames emanating from substances that contain Of other sub-
stances only
neither carbon nor hidrogen, it is yery probable, that ane. balpiiur aid
e
948 NEW CLASSES OF GALVANIC CONDUCTORS.
phosphorus them produce the phenomena of the partial insulation of the
pi negative effect. With respect to sulphur and phosphorus, F
have proved this by experiment ; and I am disposed to ex-"
‘tend it by analogy to all substances of the same kind.
Flame of sul- ‘ The uninsulated flame of pure sulphur, applied to either
ais pole of the pile, acts as a perfect nonconductor. It is im-
es ‘possible to discharge either of the poles by the application
of this flame; and the opposite pole shows no mcrease of
intensity by this contact. Hence’ it follows, that the two
wires connected by the same flame*of burning sulphur re-
main equally msulated;-and if a communication be esta-
blished between this flame and the ground, it is still the
Theaction same. The flame of sulphur, therefore, msulates the gal-
does not be- yanic electricity as perfectly as the substance from which it
Jong to the .
flamcitself. €manates; and consequently the fourth class of efiects do
not depend on the dispersive property of flame, as flame.
Its connexion ©n the contrary, the tntimate connexion of these phenomena
with chemical with chemical affinities is demonstrated, by joining with the
affinity shown
by additions to Sulphur some hidrocarbureited substance. ‘Thus on con-
the sulphur. necting the polar wires by the uninsulated flame of a match,
or of a thread dipped m sulphur, the divergence is null at
the positive side, and extreme at the negative.
Flame of phos- ~ As to the flame of phosphorus, it cxhibits a very remark-
ot cf the able property, in belonging decisively to the fifth class: that
fifth class. is to say, applied individually to each pole, it acts as a per-
fect conductor; but the moment the two wires are united in
it, the positive side is found to be completely insulated,
while, with respect to the negative pole, the conducting
power continues in full energy. I shall not enter into the
The experi- particulars of the experiments, as they were conducted pre-
aang ah cisely in the same manner as those already mentioned : but
the phospho- I shall observe, that, to satisfy myself whether the moisture
rus being wet, adhering to the sticks of phosphorus, taken from under wa-
ter, bad any influence on the phenomenon, I several times —
took the precaution, carefully to wipe the pieces I intended J
to employ, and then to keep them a whole day in a phiak J
filled with calcmed muriat of lime. ° This perfect desicca-
tion did not affect the phenomena. Neither did brown and
“opake phosphorus, obtained directly from distillmg the acid
with charcoal, differ in its effects, or in their degree, from
that
or impure.
HISTORY OF PRUSSIATES. | 249
that which I had brovight by subsequent operations to that
colour, semitransparency, and fracture, which indicate its
greatest purity.
Perhaps we miay infet frorit this, that the impurity of Brown phos-
brown phosphorus does uot arise, as some have supposed, we des i
from a portion of carbon carried over by the phosphoric va< impure by cars
pours. In fact, if the smallest portion of carbon, burned bon.
with sulphur, immediately communicate to its flame pro~
perties absolutely different from those of the flame of pure
sulphur, analggy leads us to expect similar effects from car-
bon incorporated with phosphorus. But I found nothing of
this in the combustion of brown phosphorus. I am free>to
confess, however, that. this is an argument of no «great
weight, particularly as the most essential point of compati-
son is still wanting, for I have never been able to succeed in
burning together phosphorus and charcoal mixed in different
proportions. |
(To be conéluded in our néxt.)
Il.
Facts ced a History of Prussiates. By Mr. Provsr,
(Concluded from p. 109.)
Some Precijitations by the Simple Prussiaté.
Tus prussiate, with the metallic solutions, gives diffe- Precipitates
rent results from the triple prussiate, some of which. had With the sim-
: : ; é ple and triple
already been noticed by Scheele. The foliowing are those I prussiates dif-
have observed. . . fer,
Silver, with the triple prussiate, gives a white precipitate, Silvas,
which soon turns blue, in consequence of the white prussiate
of iron mixed with that of the silver, ;
With the simple prussiate it produces a white curd, that
does not change. -
Gold is not affected by the triple prussiate. Gold,
Vou. XVI.—Avueust, 1307. Ss With
\
950 HISTORY OF PRUSSIATES.
With the simple prussiate it gives a white precipitate, that
turns to a fine yellow. This precipitate is a true prussiate
of gold, and does not fulminate by exposure to heat. Dis-
tilled in a retort it gives out water, empyreumatic oil pretty
abundantly, and gaseous oxide of carbon that burns with a
blue fiame. The residuum is gold mixed with powdered
charcoal. I find no mention of ammonia in my notes, whe-
ther it were forgotten I do not kuow.
Molybdicacid. | Molybdic acid has no effect on either of the prussiates.
Tungsticoxide Neither has oxide of tungsten.
Titanium. Titanium, with the triple prussiate, afforded prussian blue,
in consequence of the iron retained by the oxide. ay
With the simple prussiate it gave yellow oxide of iron,
such as this prussiate produces with solutions of red oxide.
I have never yet been able to obtain titanium perfectly free
from iron.
Uranium. Uranium gave a blood red precipitate with the triple prus+_
siate. With the simple, a yellow white.
Cobalt, Cobalt gave a grass green pr ecipitate with the triple prus-
siate. With the simple, a light cinnamon.
Nickel: Nickel gave a greenish white precipitate with the triple
prussiate. With the simple, a yellowish white.
Manganese. Manganese gave a peach blossom precipitate with the tri-
ple prussiate. With the simple, a dirty yellow. ~
Copper. Copper gave a fine crimson with the triple prussiate. With
the simple, a yellow. ,
Muriate of White muriate of copper, or that in which the oxide is at
copper, (a> ty @ . = a i s . . '
PP a minimum, dissolved in muriatic acid, gives with the tri-
ple prussiate a white precipitate, but tinged with a little
crimson, It appears, that the precipitate would be white,
if the muriate were completely free from oxide at a maxi-
mum: but the solution of this muriate is like that of iron,
it is difficult to keep it at a minimum of oxidation, in consé-
quence of the action of the air.
With the simple prussiate this muriate gave a perfectly
white curdy precipitate. A few drops of solution of pot- .
ash took from it its oe acid, and turned it yellow, which
is the colour of oxide of copper at a minimum.
Platina. Platina afforded nothing with either of the prussiates: but
I find a memorandum, to examine it again.
Prussiate
HISTORY OF PRUSSIATES. 95)
Prussiate of mercury is obtained, as is well known, by Prussiate of
treating red oxide of mercury with prussian blue. This salt oe
easily crystallizes in tetraedral prisms. It is always opake,
It may retain potash, as will be seen presently, if there were
any in the prussian biue. It equally retains oxide.of iron, as
may be seen by the following experiment. Heat a few grains
‘with muriatic acid in a little matrass, and white prussiate
will be precipitated.
To free it from iron, its solution must be boiled with red Freed from
oxide of mercury repeatedly: each time it deposits oxide of “°™
iron, but this depuration is tedious. The prussiate of mer-
. cury changes its state by being boiied with red oxide, and
appears to take up a surcharge; for it no longer crystallizes
in prisms, but in small groupes of very fine needles. Theit
solutions too require to be farther concentrated; and dis=
solving the crystals afresh does not bring them back to their
original figure.
This salt heated in a retort is easily and wholly decom- Decomposéd
posed, if the fire be not urged too strongly. It is sufficient >Y heat-
to heat a few grains in a tube of three or four lines diameter,
closed at one end. If, while thus heated, the open end be
exposed to flame, the prussic gas mingled with gaseous
oxide of carbon takes fire. The flame is red and blue, ter-
‘minated by a yellowish aureola. One hundred grains of
ptismatic prussiate gave one time seventy-two grains of mer=
cury, at another seventy-two and half. The residuum of
‘eight or nine grains was a mixture of charcoal and carbo-
“nate of potash. This is nothing extraordinary; for the alkali
cannot decompose prussiate of mercury, and no doubt it
was contained in the prussian blue, which was that of the
‘shops. —
The products that arose in this distillation were ammonia; Products,
‘bil, and this even in tolerable abundance} and a mixture of
carbonic acid gas, and carbonic oxide.
There does not appear to be any prussiate of mercury The oxide of
with oxide at a minimum for its base; for the prussic acid si ws ih ,.
applied to mild muriate cf mercury, or to the nitrate with base imum.
at a minimum, eliminates a portion of the mercury, and pro-
‘duces a prissiate with base of red oxide, like that obtained
directly by treating red oxide with the acid,
oh 52 The
952 HISTORY OF PRUSSEATES.
Red oxide of | The red oxide of mercury equally decomposes. the simple
9. ata al prussiate. . The potash too is separated fiom it ; and as this
prussiates of .has no action on the prussiate of mercury, the prussiate cry~
potash, -——__staiiizes amidst it. It likewise decomposes the ‘triple prus-
siate completely, but this requires long boilings.’, In. this
process, the black oxide in the triple prussiate passes to the -
‘state of red oxide, and is deposited as an ochre. Part.of the
mercury gives out the oxigen requisite for this, and hence
it-is found in the metallic-state among the oehre precipi- _
tated ; but without this superoxigenation of the iron, which
diminishes’ the. affinity of this metal; the oxide of mercury
probably would not decompose a combination so solid as.that
of the triple prussiate.
Prussiate of The aqueous sulphuric acid has no action on fli of
panies ts not . mercury, even. with heat... Not the aii smell of prussic
ecomposcd
by sulphuric ° gaS 1s given out.
acid diluted, Potash saturates the sulphuric acid as a vehicle of the
prussiate, but occasions no precipitate. ; D
Concentrated sulphuric acid destroys the prussic, gives out
sulphurous acid, and thus.destroys all means of comparison.
or by Nitric; Nitric acid is not-more successful even with boiling. At
the beginning, indeed, a little nitrous gas is.perceived; but
_ this, no doubt; 1s oceasioned by the black oxide of iron con-
‘ tained in the prismatic prussiate.. The prussiate, however,
crystallizes in the midst of the acid; and Sega ABR
this acid without precipitating any thing. ,
but itis by the . But it does not elude the: action of the biti ony pene “AR
enna like manner. There isa separation of prussic gas,.a com-
plete decomposition, and the prussiate is totally changed
into corrosive sublimate. Accordingly, ‘alcohol , dissolves
the saline residuum of this process completely; and we find
nothing but sublimate on trying it by reagents: . It is well
known, that alcohol does not dissolve the prussiate of. mey
cury.
Solublein pot- Potash dissolves the prussidte of mercury abundantly, by
ash. the assistance of heat; and this salt crystallizes in it on cool-
ing. Alcohol separates it too, and it is found entire. -
Decomposed Muniate of tin at a minitnum, and hidrosulphuretted wa-
by muriate of
tin, and hidro: te! decompose this prussiate instantly, and the pai acid
sulphuretted is set free. 4
water; . It
HISTORY OF PRUSSIATES.- 253:
. {it has been seen, that muriatic acid acts effectually on but not by mu-
this prussiate: it might be supposed, therefore, that muriate a ea
of ammonia, which offers the prussic acid a principle capa-
ble of uniting with it, should make a change of bases ;, but
it does not. Ifa solution of prussiate of mercury be heated
with muriate of ammonia, nothing new 1s produced, and _al-
cohol separates them completely. . Potash, and limewater
precipitate nothing from the mixture, not an atom of corro-
sive sublimate; and the green suiphate of iron, which would
not fail to form a prassiate of iron with that of ammonia, if
if:met with any in the liquor, does not experjence the least
change.
Prussic gas.
- On heating 1440 grains of ‘triple prussiate in a; retort, Prussic gas,
with a sufficient quantity of dilute sulphunic acid, four ounces
[2304 grs.}..of alcohol were impregnated with about 80 gis.
of gas. I kept the alcohol ina jar in a mercurial trougl:
the gas dissolved in it rapidly, but it would have taken up
much more. The water of the intermediate receiver too was
loaded with it: its smell was suffocatingly pungent, and its
kernel flavour was extremely strong. This water did not
render,that of, barytes turbid.. The ges has a constant ten- -
dency to escape, and.is perpetually raising up the cork. If
asmall matrass filled with the solution be immersed in hot
water, the gas separates rapidly, and burns at the orifice:
gn bringing a candle near it, smoke is perceived; no doubt
. because a part of the charcoal escapes, as in the combustion
five months it becomes yellow. © It gradually loses its smell
of volatile oils.
aPrussic acid dissolved. in water; and kept in a bottle prrccic acid de-
closely stopped, is decomposed spontaneously. In four or composedspon-
_ taneously in
- { [ c ? water.
grows, ‘turbid, and: deposits a coffee coloured sediment,
which, after being heated, exhibits all the characters of char-
‘goales i:
» By distillation, it affords a little water, prussic acid, and pecomposed
ammonia, ~The carbon is azotized; and it acquires one of by heat.
the principles, which the acid relinquishes on being decom-
pased, for, on heating it with carbonate of potash, it afforded
me a lixivium capable of making prussian blue,
boi4] But
954 } HISTORY OF PRUSSIATES.
But while the carbon in separating retains azote, the
greater part of the latter, combining with hidrogen, forms
ammonia. Thus ammonia is found in the yellow liquor,
with the remainder of the acid that has escaped decomposi-
tion.
Solution of Prussic acid dissolved in water does not penta the solu-
prussic acid tion of green sulphate of iron turbid, till it bas undergone
and sulphate 5 ' : : aaah
of iron. the changes just mentioned ; it then affords blue with it, from
the concurrence of the ammonia recently formed.
Solution dis- Finally, this solution being distilled affords prussiate of
tilled. ammonia, and nothing-more is found in it but some parti-
cles of carbonaceous matter, which fall down. It would
have been of importance to ascertain, whether there were
any carbonic acid with the ammonia, but I forgot it at the
time. I intend, however, to examine it again. ;
Solutionofthe The alcoholic solution keeps perfectly well. Hence we
acid in alcohol may even infer with some reason, that, as alcohol is better
keeps very
well. adapted than water both to dissolve and retain it, the prus-
Inference. —_ sie gas, considered too with respect to its qualities of being
aromatic and inflammable, perceptibly approaches nearer to
oily, combustible, and. waa pr ioe than to saline sub<
stances.
General de- From these facts it follows, first, that. there is but one
ductions. prussiate of mercury, the base of which is at a maximum:
secondly, that the augmentation of attractive’ power,
which the prussic acid borrows from the black oxide, when
it has to combine with potash, or the red oxide of iron, and
on which Berthollet has so justly-insisted, ceases to be ne-
cessary, when it has to unite with the oxides of gold, silver,
copper, cobalt, nickel, uranium, mercury, &e. We see, in
fact, with regard to the latter, this acid, the affinities of
which are so sluggish, so little adapted to entitle it to the
name, has notwithstanding no need of black oxide, to fur-
nish with mercury a saline compound, very soluble, very
crystallizable, and, in short, possessed of all the characters,
that distinguish the most perfect compounds. 'To these
anomalies let us add those it has of preferring mercury to
all the alkalis; not yielding its oxide either to the nitric
or sulphuric acid, each of which is so far beyond it in
strength ; and sinc to yield it only to the muriatic acidy
~ which
HISTORY OF PRUSSIATES. 955
which is in so many respects inferior to the sulphuric and
nitric.
Lixivium of animal charcoal.
Equal parts of charcoal of blood and carbonate of pot- Prussic lixi-
ash, heated to redness in a covered crucible, always afforded “'"™-
me the richest lixivium.
Supposing, that the carbonic acid might be an obstacle Not improved
‘to the saturation of the potash, I added lime to the mixture, by lime.
but the lixivium was not improved by it.
I heated red hot, for half an hour, a mixture of 144 OTS.
“of charred blood, with as much carbonate of potash. After
lixiviating, 104 ers. were left, 40 having been destroyed.
These 104 ers. were again treated with 144 of carbonate
of potash, and were reduced to 62, so that the loss was
AQ. ‘
The lixivium of each of these was saturated with the so- First lixivium
lution of the sulphate of iron of the shops; and the blue S‘Toms®st.
produced by the former, after brightening, was double that
afforded by the second.
- To ascertain the influence of temperature, I tried three The red heat
mixtures of equal parts. The first was kept red hot half ™ust be kept
an hour, the second an hour, the third an hour and a quar- ies gate
ter. The lixivium of the first produced but little blue;
those of the other two a great deal, and nearly in equal quan-
tities. These results prove, either that the simple prussiate,
which predominates in the lixivia, is preserved amid the car-
bonaceous alkaline mass, or that it is reproduced as fast as
jt is destroyed.
Powdered charcoal of blood grows moist in the air. By Calcined blood
~washing, it affords muriate of soda, and carbonate of soda deliquesccnt.
‘united with a little prussic acid.
Charcoal of blood lixiviated with potash a second time Exhausted by
still affords blue, though but little; a third time, the blue is successive ld.
less perceptible; a fourth time, there is none. This char- ae
‘eoal, thus exhausted, and heated red hot, incinerates with ypcinerated.
great facility, and without exhaling any smell of ammonia,
as that does which is burned immediately after having been
exposed to distillation. It seems as if it became more coms
bustible in proportion as it parts with its azote, and ap-
proaches
\
256 HISTORY OF PRUSSIATES.
proaches nearer to vegetable charcoal: nitric acid, however,
cannot inflame it. As azote is capable of forming solid.
Would itmake combinations able to resist a high temperature, what would
superior 61¢e] ? ae the influence of animal Ehret in the formation of
steel? Workmen employ sheep’s hoofs for casehardening ;
‘has their charcoal any advantage over that of wood?
Prussiate of Equal parts of washed charcoal of blood and potash de-
cenahaelly a carbonated by lime, or lapis infernalis, afforded me by dis-
i) tillation simple prussiate of ammonia, and a great deal
of gas, which had the prussic smell, and burnt with ; a red
flame.
., Equal parts of the same charcoal and oxide of manga-
nese affordéd me carbonate and prussiate of ammonia.
But it doesnot | The desire of fabricating gmmonia with advantage led
saat eo me to the following experiment. I distilled a mixture of
ammoniac. six drachms of charcoal of blood, two drachms of clay, and
- > \9 .two 6f muriate of soda; but the product of sal ammioniac
was less than I had expected.
Prussiates from, ‘All vegetable charcoals azotized are fit for making prus-
some vegetable
charcoals, sian blue. Thus those of gluten, chich pease, indigo, and
pitcoal, afforded me tinging lixivia, sometimes mingled with
hidrosw!phuret : those of sugar and sugar of milk did net
-give the slightest indication of blue.
Charcoals of |. . The charcoals of ‘the chesnut tree and heath, which
se hee tao -Staiths prefer, because they have the property of not burn-
not contain ni- ing any langer than they are blown, do not derive this from
vais azote; for their lixivia contain no prussic.acid, .
Socens of tar. Cream of tartar heated red hot affords a lixivium, ak
ee 7 Ais does not afford the least indication of it: two parts of cream
tain propor- of tartar and one of sal ammoniac, the same: but.one part
tions afford a of. sal ammoniac, with four of cream of tartar, yields a hxi-
ates. noe vium, that contains simple prussiate, and affords blue with
the green sulphate of iron of the shops. Cream of tartar
aud nitrate of soda afford nothing,
This: proves, that animal char coal is preferable to vegeta-
le on account of the azote merely. It also follows, that, if
we should some time or other discover an azotized compound
more capable of sustaining a strong heat than the ammonia-
gal salts, we might be able to form prussic acid, perhaps, ina -
Jess laborious manner than by means of animal charcoal,
Examination
o
I divided a lixivium into two equal parts. One was pre-
_ HISTORY OF PRUSSIATES. G57
Examination of the lixivia.
By distillation these constantly give prussic acid and Lixivia exami-
ammonia, the origin of which we have seen above. nee.
They also. contain carbonate of potash in large quantity ;
simple prussiate of potash ; triple prussiate of potash; sul-
phate of potash; phosphate of lime; and sulphur,
They let fall the phosphate of lime as they are evaporated;
how it was sustained in them I know not.
If a portion of the lixivium be saturated with sulphate of
“iron, and the liquor with which the blue produced is bright-
ened be examined, phosphate of iron will be discovered in
‘it. It was this phosphate, that led, Westrumb to suppose the
acid of prassian blue to be the phosphoric.
‘Alevhol ‘applied to the concentrated lixivia takes from
them some simple prussiate ; but it appeared tome dificult,
to exhaust them of it by its means. The triple prussiate
remains in the lixivium with the carbonate.
Of these two prussiates one only can produce prussian
blue with the red oxide of iron, which is the triple prussiate,
and this because it contains black oxide of iron. The sim= Common suk
‘ple cannot, because it is destitute of this black oxide: but Phate of iron
3 E : Uw ‘ : more advan-
if acquires this property, and is converted into triple prus- tageous for
qu p g
siate, as soon as the lixivium is mingled with the. sulphate ee Lees
of iron of the shops ; and consequently, if a sulphate com- the red sul-
pletely red be employed, we shall have much less prussian Phate.
blue, because, the Black-oxide failing, it cannot forma tri-
ple prussiate and afford blue with the same sulphate. Two
experiments will render this evident.
Experiment.
cipitated’ with red sulphate, the other with the green sul-
phate of the shops. The surplus oxides being separated by
the brightening liquor, the blue from the second was found
to be to that from the first in bulk as four to one.
The first lixivium, when filtered, had a strong keruel smell.
I saturated it with potash, to fix the free prussic acid afresh;
an atom of blue, but with the green it yielded a great
al. Hence we may conclude, that a carbonaceous lixivium
¢annot yield all the blue it is capable of producing with the
; solution
fo trying it afterward with the red sulphate, it did not af-
f
958 HISTORY OF PRUSSIATES.
solution of red oxide, without the assistance of black oxide.
Hence the risk of losing all the simple prussiate contained in
a lixivium, if we were to use only a sulphate, the oxide of
which is completely red; though this I formerly recommended,
The blue from but it was from mistake. I was not aware, that, if the green
the green sul-_sy]phate have the inconvenience of affording a pale prussian
phate is pale at : : i
first, but grows blue, the oxigen of the atmosphere soon remedies this; and
deeper by ex- that it has ria essential advantage of furnishing the simple
ag ee prussiate with that portion of black oxide, which is necessar y
to convert it into a triple salt, and enable it afterward to
produce blue with the red oxide. Thus practice had at-
tained the object before theory: but practice in turn be-
comes a rational process, as soon as theory comes to its jus-
tification. Two other experiments will corroborate this.
Alumemploy-. The lixiviums are commonly precipitated by a solution of
eA four parts of alum, and one of the sulphate of iron of the
shops.
but ithasno - I divided one of these solutions inte two parts. One was
chemical effect sy neroxided by the oxigenized muriatic acid, the other was
in the process. P RN :
‘not. I afterward saturated them with the carbonaceous re-
siduum. The common solution afforded abundance of blue,
but the superoxided yielded only a pale precipitate, which
was nothing but a little blue diffused among a great deal of
alumine. This experivent does not differ at bottom from
the preceding: it has only the advantage of showing, that
alum is merely a passive ingredient ‘in forming prussian
blue. si
The lixiviam The lixiviums of the manufacturer, therefore, are not like
from blood not those made by treating prussian blue with an alkali. The
precisely the i Rs
came as that Jatter will always afford abundance of blue, because it is
from prusssan made a triple salt.in the operation itself: but this is not the
blue itself. : : : :
case with the former; they afford blue only in proportion to
the quantity of triple salt they contain, and to angment this,
or to convert their simple prussiate into it, it 1s indispensable
to employ a sulphate, that, if not strictly green, at. least
is so in a certain degree; and this is precisely the’ éase
with the sulphate of the shops, however long it has been
made. ,
In the calcina- From these details we learn farther, that, if the lixiviums
tion of the egntain but a certain portion of triple prussiate, it is either —
blood probably because
<
HISTORY OF PRUSSIATES. 259
because the charcoal of blood has-not iron sufficient to con- part of the trie |
vert all the simple prussiate that is formed during the calci- Ay eenpe
nation into a triple salt, or that part of this salt is again
reduced to the state of simple prussiate by the loss of part
of its oxide, as we have seen takes place when it is heated
alone. Of these two opinions, however, I should be in-
clined to adopt the jatter, because I have observed, that the’
ashes of the charcoal that has been lixiviated always afford
a great deal of iron: we have no reason, therefore, to sup~
pose, that in calcining the carbonaceous alkaline mixture
iron is wanting to the prussiate; and indeed, if we reflect
on the subject, it is surprising, that the triple prussiate,
which actually exists in the lixiviums, should have been ca-
pable of defending its oxide against the effects of the car-
bon continually tending to reduce it. 'The whole of this,
however, is at present very obscure: we neither know the
period when the prussic acid is formed, whether it be de-
stroyed to be again reproduced, nor, lastly, the degree of
heat required to obtain the greatest possible quantity of
either of the prussiates, that are the objects of the manu-
facturer.
' ‘The existence of the triple prussiate in the lixivia may be Proof that the
demonstrated by the following experiment. eke —
_ Saturate a lixivium with aqueous sulphuric acid. The ne Ream ie
carbonic acid first flies off, and next the prussic acid of the
free prussiate. After this, heat must be applied, when the
triple prussiate is attacked, and the white prussiate of iron
is made apparent. Beside this, concentrated lixivia long
kept déposit octaedral crystals of triple prussiate. ’
The prussic lixivium has two very distinct tastes; one of Their quality
potash, the other of kernels. By the latter we may judge at may be judged
once of its quality, If it affect the palate but slightly, the 2 Scan ae
lixivium is defective, either because the mixture was insuflici-
ently heated, or the animal charcoal in too sparing proportion,
I am of opinion too, that the calcination of the mixture in the
open air does not contribute to the augmentation of the
prussiate ; and that it would probably be more advantageous,
and save trouble, to heat it in covered crucibles in a reverbe-
ratory furnace, since it has been proved, that stirring the
mixture is not necessary to the success of the operation.
When
g60 HISTORY. OF; PRUSSIATESs
Previous'to When it is necessary to concentrate the lixivium, either to
Plirigade Bp keep it, or that it may take up less room, we should previ+
phat should be ously take care, as Curandeau perceived, to prevent the sim-
added, to pre- te : AE :
went the loss of Pe prussiate from being destroyed. Thisiis réadily done by
thesimple adding green sulphate in small quantities. In this way it
alee c dissolves completely. in the lixiviam, which first grows redy
then becomes again yellow. An excess of sulphate does not»
alter it, because the potash, which predominates, reduces it:
to an oxide; and this falls down, without being able to pass
tothe state of a prussiate. To attain this, it must: present
itself accompanied. by an acid; for the oxide here spoken of
is,entirely that at a minimum, which has no action on the
triple prussiate, i
Advantage of ~'Lhave divided a lixivium into two: equal parts: one was’
this. widtsied, or converted into a triple salt, by the green sul-
phate; the other was not. lafterward. distilled them: and
the first gave no indication’ of ammonia; the secondfur-)
nished it asusual. It is indispensably necessary therefore, to:
prepare the lixivia before they are concentrated... Finally,
Phe red oxide neither the red oxide, nor its sulphate, as,Scheele found,
does not unite
with the sim. ¥8-capable of dissolving in the simple prussiate, and giving:
ple prussiate, it the properties ef the triple. This éxide too, though
adapted to become the basis of prussian blue, is equally un«
or decompese able of itself, to decompose the triple prussiate ; ; at aenpit
Hs ed presented to it in solution by an acid:
Reccpitalation: '
t » i XT
Component Prussic acid is composed of carbon, nitrogen, and ‘hidres
parts of prus- gen, in proportions of which weare yet ignorant. We can
East only conjecture, from the great quantity of carbon it leaves
im several instances after it is destroyed,. that this principles
enters into its basis in a very large proportion, compared.
Nooxigen, With the others, Neither is there any fact, that indicates
oxigen to make a part of it; and indeed, from the well
known affinities of its three elements, added tothe circume
stances under which the acid is) formed, we can Rg
think it does... )
Has fewacid ‘The prussie acid in its separate state has very fei of the
qualities, common gualities of acids, It -has not-a sour taste; it does
not
é
“
HISTGRY OF PRUSSIATES.
not redden litmus; it does not dissolve in water, the proper
menstruum of acids, so well as in alcohol; and it is even de=
composed in it spontaneously without access of air. With
alkalis it forms combinations so imperfect, that we find in
them the specific properties of their component parts scarcely
altered; and the weakest of all acids, the carbonic, is capa-
ble of decomposing them. In short, its combustibility, taste,
smell, generation amid volatile oils and kernels, and quality
of keeping in alcohol, form an assemblage of properties, by
which it approaches much nearer to oily and inflammable
productions than to saline substances. |
_ The prussic acid, however, notwithstanding its little sa-
line energy, attacks the oxide of mercury at a maximum with
great advantage; and with this oxide it furnishes a saline
combination so strongly characterized im its qualities, that
we are obliged to acknowledge it acts under certain circum-~
stances as one of the most powerful of acids. ‘ In fact, the
prussiate of mercury wants nothing to entitle it to rank with
the most perfect. métallic salts; and what may perhaps be
deemed astonishing is, to see it refuse to combine with the
oxide ata minimum; yet, from the effect of concurrent affi-
nities, of which there are other examples, it raises it to the
state of an oxide at a maximum, separating one portion of
the metal, to form a prussiate with the other.
Prussic acid has no action on the red oxide of iron; but it
very readily attacks the black oxide, and produces with it
white prussiate. It is true this prussiate 1s not strictly white,
on account of the difficulty of preparing a precipitate with
the green sulphate totally free from a surplus of oxide;
- and aecordingly itis always greenish: but as.it becomes a
perfect prussian blue by drying , there can be no doubt, that
_ the prussic acid and the toate of green sulphate, if not af-
_ fected by contingent circumstances, would furnish @ prus-
siate as white as that which we obtain in a more easy manner.
..Prassian blue is not a single compound, as had been sup-
posed. This the following observation is sufficient to show.
It is known, that the base of this blue is the red oxide of
iron: but, if this oxide alone were sufficient to make prussian
| blue, why is not this blue afforded by prussic acid and red
oxide? and why do not the alkaline prussiates produce it
: with
266
More analo-
gous to oilsand
inflammables.
Yet toward ox-
‘ide of mercury
itacts as a powe
erful acid.
Pussiate of
mercury.
Action of prus-
sic acid on irons
Prusisan blue
not a single
compound,
962 HISTORY OF PRUSSIATES:
with solutions of this oxide? Something else therefore is
wanting to the prussian blue, and the following facts will
complete the proof. oA
Proofs of this. On applying potash to prussian blue we obtain a yellow
' chrystallizable salt, which has always a constant proportion
of black oxide of iron. If we employ this yellow prussiate
to reproduce prussian blue, the oxide repasses into thé.
_new combination with the prussic acid. The black oxide
then is a necessary element in the formation both of the —
crystallizable prussiate and of prussian blue; as well as of
all the metallic prussiates, that are prepared with the trip!
prussiate of potash. ;
Prossiids hia There are some metals, that are capable of forming both
ed by different simple and triple prussiates, as copper, silver, manganese,
metals. cobalt, nickel, uranium, &c. There are others, that form
only asimple prussiate, as gold, mercury, &c. There are some,
that admit only of a triple prussiate, as iron, &c. And lastly
others appear to be incapable of combining with the prussie
acid. Except prussian blue, however, and the prussiate of
mercury, we know but little of them, and they deserve far-
Union of black ther examination. The black oxide of iron combined with
oxide of iron prussic acid can pass from one combination to another with-
with the prus- Sie. : eee
paeeesa out changing its state. ‘The base of this combination may
even be raised from a minimum to a maximum, without the
black oxide participating in the change. The combination
of the acid with this oxide is bound by an affinity so powers
ful, that the alkaline hidrosulphurets cannot separate them ;
or attack the oxide, if you please, either in the triple prus«
siate, or in the prussian blue. 4
_The prussic acid, combined with that portion of black
oxide which enables it to form triple prussiates, either alkas
line or metallic, is a peculiar combination, the existence of
‘which is not doubtful, but of which we know nothing sepa
rately from these prussiates.
Heat reduces The triple pruissiate of potash cannot support a red heat,
the tfiple prus- without losing the black oxide, and consequently being re-
siate of potash : i
to simple, duced to a simple prussiate. a La
and decompo-. Lhe simple prussiate is decomposed likewise, but by a far
ses the simple ower temperature: its acid is destroyed, and reduced to am-
prussiate. _ monia and carbonic acid: and 4t is the destruction of this
salt
STOVE FOR HEATING AND DRYING. 063
salt by the heat of ebullition, that injures the lixivia for pre-
paring prussian blue.
The simple prussiate assumes the character of triple prus- Simple prussi-
‘ : - : A . ,_ ate converted
siate, as soon as black oxide of iron, or a salt with this oxide into triple,
for its basis, is presented to it; and thus acquires, beside the ‘
advantage of being crystallizable, that of not being decom-
posable at a boiling heat.
- This prussiate, which was the test liquor so much sought The testliquor.
after by chemists, does not afford prussian blue with solu-
tions of red oxide of iron; but it produces this blue if they
contain any black oxide, because its acid immediately at-
taches itself to that portion of the black oxide, which will
serve as an intermedium between it and the red oxide.
The triple prussiate of iron, or prussian blue, strongly Necomposi-
heated, is reduced to ammonia, carbonic acid gas, gaseous tion of the tri-
. : ple prussiate of
oxide of carbon, steeled iron, and carbon. iron,
_ The prussiate of mercury affords the same products by its
decomposition, and likewise a certain portion of oil.
: The lixivia of the carbonized materials contain little triple ye tixivia,
prussiate, but a great deal of the simple; and they muft not
be boiled down, till the constitution of the second is strength-
ened by an addition of black oxide, or of green sulphate.
- To obtain from these lixivia all the prussian blue they are How to obtain
capable of affording, it is indispensably requisite, toemploy a paige cag
sulphate of which a portion at least is green; without which
the simple prussiate they contain cannot furnish blue with a
sulphate of which the base is completely red.
_ To conclude, if the reader take the trouble to compare
this paper with Scheele, he will find, that all the truths it
contains were perfectly known to him; but I conceived they
required to be more fully explained, which I have here at-
tempted.
& of mercury.
Iii.
An Account of a Stove for Heating Rooms, or Drying different
Articles; by Mr. G. Frexp, of Newman-Street.*
Tue various advantages of heating, boiling, steaming,
evaporating, drying, ventilating, &c., are united in this stove ;
. al so
* Fransactions of the Society of Arts, for 1806,
264%
STOVE FOR HEATING AND DRYING:
so that it is capable of being applied to maiy useful purpss
ses, both in domestic economy and the arts: on which acs
count, a silver medal was voted by the Society of Arts to
the inventor. The subjoined description, with the annexed
Description of plate, will more fully explain its design.
the stove,
~ Figs 1. P). VIL Represents a Jongitudinal section of the
stove, showing the couirse of the air from its entrance into the
flues of the stove at A, to its entrance into the upper cham-
ber of the stove at B: and also, the course of the smoke from
| the fire-place at C, till it escapes from the stove at D. E, FE,
are the doors or openings of the fire-place and ash-hole.
Fig. 2. Is a similar section at right angtes with the above;
exhibiting the course of the air through the chambers of the
stove, from its entrance into the chamber No: 1. at B to its
entrance beneath the fire-place at F.. This figure also shows
sections, of the flues, with the divisions Sivan which the air
and smoke pass separately, the smoke flue. in the centre,
and the air flues on each side. G, G, are doors and openings
_ through which the articles to be dried are introduced. into
Its use asa dry=
ing stove,
and in warm-
ing tooms,
the chambers.
When the fire is lighted, and the doors of the charhbers;
ash-hole, and fire-place, closed, the air by which the fire is
supplied enters at A, Fig. 1, passes through the air-Hues a, a,
a, a, enters the upper chamber at 13, traverses and descends
through the chambers No. 1, 2, 3, and arrives beneath the
fire at F, Fig. 2. Having supplied the fire with oxigen, it —
passes through the flue with the smoke, and escapes at D,
heating in its protracted course the chambers and air-flies,
As the cold air enters the stove at A, immediately above a
plate forming the top of the fire-place, and pursuesa similar
route with the jire-flue, it enters the chambers very much
heated and rarefied, \ Hence any moist substance placed in
the chambers évapovates, in consequence not only of the
heated flues circulating round them, but of a stream of warm
rarefied air, which, while it continually causes evaporation, as
continually bears away the exhaled moisture in its passage °
to the fire, thus imitating the gradual and efficacious plan
of nature in drying by the sun and air. While these effects
dre taking place within the stove, part of the air which enters
at A, Fig. 1 and 2, passes through air-flues on the other side —
of
.
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Be STOVE FOR HEATING AND DRYING. 265
Oe die EEA ii CR a nase
te hand or face be then brought near, they would.
n ae ve a stream of warm me oe gegen from the —
pane
bas. Py ‘Bis ae el rid ehipatated ae to dayne, Milk evapo-
oe i - - ratedto dryness
yout burning or discolouring i iff and have dried cherries, ieee Brick
. an other fruits, so as to imitate those which are ing, and other
from : dri delicate pro-
reashiell om abroad. ~ Thave repeatedly ied colours and ey >%
the most « delicate aubaba nese} without the slightest i injury to
them, even though | the operation proceeded quickly. 5b ;
The height of the stove is about 5i feet: its diameter gr Constnicton,
feet, and that of the flues 4 inches. The external part is
constructed of brick, and the internal parts of thin Ryegate
or fire-stone, except the top of the fire-place, which is a plate
of cast iron. Were it to be wholly formed of iron, its effects
would necessarily be more powerful.
Represents an extension of the plan, in which The plan may
mnnected wath be extended.
Re a.
d bye an opening
ue at L.
ion to the uses already pointed out, this stove Various pur-
ind ex ‘sel ing Poses to which
Bak : ive B it may be ap-
Le Gale Sas plied. --
Its form and di-
mensions ad-
mit of consi-
derable yaria-
tions.
STOVE FOR HEATING AND DRYING.
with the great fires they employ for their boilers. It has
been shown to be useful in the confectioners art, and pro~
bably it. may be equally so in’ baking biscuits for the navy;
nor less so in drying linen for the laundress, dyer, calico-
printer, and bleacher. I have myself found it well accom-
modated for a chemical elaboratory.
The efficacy of the stove in ventilating, boiling, and
steaming may easily be shown. In manufactories and rooms
generally the heated and noxious part of the atmosphere.
ascends towards the ceiling: if then the air-flue M, Fig. 3,
is continued upward according to the height of the room in
which it is placed, the air will be drawn from the top, and
the room become ventilated, while from the opening at N it
is supplied, if requisite, with warm air.
It is unnecessary to show the various ways in which a
boiler may be connected with this plan: it is sufficient to
observe, that in the space allotted for the fire-place in Fig. 1,
there is sufficient room within the body of the stove for this
purpose; and that if the circulating air be made to pass
over the boiler; evaporation may be carried on very expe-
ditiously by the air removing the vapour as it arises. Fi-
nally, if another division of the flues be made in the man-
ner shown Fig, 2, it might form a steam-pipe or fiue, run-
ning the course of the air and fire-flues, to convey steam to
one or more apartments of the stove; or extended. beyond
the stove for heatmg the room in which it stands. One of
the air-flues might occasionally be adapted to this use. Itis
obvious that the power of steam in a heated apartment
would be not only greater, but better kept up. In steaming
it would be necessary to close the apartments of the ‘stove,
and to give air to the fuel by a different course. |
As the stove is mot confined in its dimensions, so neither is jj
it necessarily of the form described in the drawing, nor are the |
apartments necessarily three: all these particulars admit of |
variation according to the local or other circumstances, It
is evident that the air-flues themselves may be converted
into chambers for drying, &c.; and the fireplace "@f Fig, 3
is well adapted to receive an apparatas for the decomposition
of coal, &c.; for producing all the effects of the thermo- 9
lamp, or illuminated smoke, &c, But it is needless to enu= §
. merate —
OXIDATIONY OF IRON. | 267
iferate the mdny economical ‘and philosophical usés to ¢
which the stove may be applied. It is sufficient for the pre- ;
sent purpose, if I have rendered the principle and plan in-
telligible, the artist and manufacturer will then be at no loss *
in adapting it to the particular ebject, which he may require
_ to accomplish:
_A certificate from Mr. S. Sellers, hEmict, Broad street,
Bloomsbury, stated, that the effects of the stove in question
fre as Mr. Field has described them in his paper.
: IV:
Friquiries concerning the Oxidations of Iron; by Mr. Dicks:
(Continued from page 226.)
Oxides by Solution:
ie aabean of iron afforded me still moré satisfactory Solutions of
results, both because they confirm and render more clear in.
those obtained by calcination, and because they may throw
much light on a number of manufactories, and si implify the
chemical theory of iron. But; convinced as I am of these
results, I offer them only as, conjectures;.since they are dia-
| metrically opposite to the present mode in which solutions
of iron are viewed, and I am always afraid of being led into
; errour.
The inconstancy of ,the green oxide, which Lavoisier and Green oxide
Mr. Proust obtained when 100 grains of iron had takén up Y">!*-
$7 of oxigen; and which, from the experiments [ have re-
lated, varies from a few hundredths to 32: could not but lead
‘me to conclude, that the properties distinguishing this oxide
i
_ from the red, are owing not toa fixed degree of oxigenation, Why?
but rather to 4 certain density, which allows the water, or the
acid, or both, to lodge in the interstices of each molecule;
_ and hence the difference of colours of these precipitates by
, alkalis, prussiates, and gallates, and their less or greater so-
_ lubility; the only properties that distinguish the green salts
from fhe red,
Soe This
268
White oxide.
Its characters.
Change of co-
Jour in precipi-
tates no proof
of a different
dose of oxigen.
OXIDATIONS OF IRON:
This reasoning led me to examine not only the red and
ereen oxides, but at the same time the white oxide lately
announced by Mr. Thenard*, of which I had beforehand:
some doubtst. Iam sorry to callin question the labours of
men whom IJ greatly esteem and respect, but L conceive [am
seconding their views, if my observations be just.
Of the White Ovide.
The characteristics assigned to this oxide by My. The-.
nard are, Ist. that it becomes green by exposure to the air;
2d. that it is changed to green‘or yellow by oxigenized mu-
yiatic acid; 3d. that when the precipitate is made in a phial,
and care is taken to stop it close, an absorption is observed
on shaking it to convert the white oxide to green; which
proves, that part of the oxigen of the air m the phial com-
bines with the white oxide, and changes its colour. I shall
take the liberty of examining these facts.
From the experiments of Messrs. Fourcroy, Proust, and
Berthollet, Mr. Thenard, and all the chemists of the pre-
sent day, are of opmion, that the change of colour-in pre-
cipitates does not in general indicate a different degree of
oxigenation. The white is that which very frequently con-
ceals the true colour of oxides in almost all metals, that are
said to be susceptible of oxigenation, as tin, mercury, cop-
per, silver, lead, bismuth, and probably manganese. This
@epends on the quantityyof acid. the precipitates retain,
* See our Journal, Vol. XIV, p,. 224.
+ Before undertaking my present imquiry I could not avoid doubting,
that a few hundredth parts of oxigen could modify the colour of metallic
oxides so far as to change them from white to green, black, &c. All the,
facts with which Jam acquainted militate against this property of oxi:
gen; consequently, I was suspicious of every precipitate, the colour of
which varied much from that of the oxides of the same metal obtained
by calcination. If white, I argued, be'the result of the combination of
iron with a few hundredths of oxigen, why does not this colour present it-
self in the course of the calcination of iron? and why in the calcination of
manganese, copper, and bismuth, do we not perceive the same phenome-
non? Besides, the only well established white oxides are those of anti-
mony, zin, and arsenic; and from the moment these become white they
never change their colour, even froma considerable over dose of oxigen. ~
they Ny
-
OXIDATIONS OF IRON. 269
they being freed from this with more or less facility, aceord-
“ang to their nature, and still more according to the circum-
stances under which the precipitation has taken place. This
appears to be the case with the white precipitate of iron.
The conditions requisite to throw down a white precipitate Conditions ree
from a green salt of iron, are: first, that the solution be quisite to pre
highly concentrated ; second, that the precipitating alkah a ere
be in some degree the same. This did not escape the saga-
city of Mr. Thenard, who recommends boiling dilute sul-
phuric acid on an excess of iron filings, that the formation
of the white oxide may be more sure to succeed, In fact,
whenever a tolerably concentrated solution of alkali is added
to such a solution of iron, the alkali first seizes a portion of
the acid, and probably a little of the water, and precipitates
a white sulphate of iron, which frequently crystallizes,
though irregularly, at the moment of precipitation, and still
retaims a sufficient quantity of acid, to be soluble in water,
It likewise constantly turns sirup of violets green, and forms Action on si-
rup of violets
a red precipitate in water coloured with litmus, as is com-
J and litmus.
amon to salts of iron with excess of oxide*,
It is easy to verify this fact in a convincmg manner, by Proofs of the
letting fall a few drops of such a solution into an excess of ft
alkali. If, after having left the white precipitate in it eight
pr ten minutes, the fluid be decanted, or if it be drawn off
* J have obtained several salts of iron, which immediately produce a
red precipitate with infusion of litmus, and at the same time turn sirup
‘of violets green. The property of precipitating infusion of litmus al- Tifuston of
“ways indicates a salt that is at least neutral, and must not be confounded mus gives Z
with the effect of simply changing its colour. In the mere change of precipitate in
colour the small portion of alkali in the infusion combines with an ex- certain cases.
cess of acid, and quits the colouring matter, which it modified. There
can be no doubt, that a salt exhibiting this phenomenon has an excess
of acid, since there is sufficient to saturate the alkali in the infusion,
without occasicning a precipitate; and on this principle is founded the
use of thisreagent. When the change of colour is accompanied with a
‘precipitate, the alkali, not finding an excess of acid to combine with,
“seizes part of that which held the oxide in solution, and the precipitated
oxide carries down part of the colouring matter with it. What appears Anomaly of
extraordinary is, that oxide of iron does not turn sirup of violets green, oxide of iron.
though neutral salts of iron, or salts with an excess of oxide, have this
_effect.
by
970 OXIDATIONS OF IRGN.
by a siphon, which is the surer way; anda few drops of
water be afterward added, to take up the alkali, that ad-
heres to the surface of the precipitate and the sides of the
glass; a mass of sulphate of iron will remain, great part of
which will dissolve in water, and exhibit all the properties
I have just mentioned. I have left this precipitate for
twenty-four hours macerating in potash, and at the expira-
tion of that time have still obtained soluble sulphate of
iron. :
4A, mmonia In a concentrated solution of ammonia, the result is still
ana eae: more striking; because, as the density of the precipitated
ly. sulphate of iron greatly exceeds that of the ammonia, the
precipitate falls quite to the bottom of the glass, and great
part of it sticking to this, escapes the subsequent action of
the alkaii; which does not happen with the concentrated
fixed alkalis, the density of which is greater than that of
the ammonia, and in consequence they envelope it on all
sides. .
Whyagreen This is the reason why these solutions, which when con-
aiacayenems centrated throw down a white precipitate, throw down a
ef green precipitate when they are diluted with water freed
from air by long boilmg. For this reason, limewater never
gives a white precipitate, even with the most concentrated
solutions, Lastly, for this reason I suspected before hand,
that the muriates and nitrates, which give white precipitates -
with the alkalis, would be precipitated green by barytes
Not from addi- and strontian water, which in fact is ee the case. The
penal oxigen. green colour cannot be attributed to a superoxidation occa-
gioned by the air in the lime, barytes, or strontian water;
for, beside that the rapidity af the operation, and the quan-
lity of air that so small a bulk of distilled water could con-
tain, would not justify such an idea, | took the precaution
to boi! the water in which I dissolved the three earths for an
hour and half,
Thesameifdi- If, instead of diluting the solution with water, it be di-
Suaaeasibe dated with sulphuretted hidrogen, in which the presence of
a eal ta oxigen cannot be suspected, the result will be still the same 3
a the precipitates formed by alkalis will be green or black,
and never white. It is trae Mr. Thenard says, that, on ponr~
ing sulphuretted hidrogen on a 2 red solution of iron, this will
yield ’
OXIDATIONS OF IRON, OF 1
yield green or white precipitates, I am inclined to think,
however, that this is rather an inference drawn by Mr. The-
nard from his manner of considermg the white oxide of
iron, than a fact that came under his observation. Be this
as it may, I can assert, that, having repeated these experi-
ments several times, frequently changing the reagents, and
varying the circumstances as much as possible, I have ob-
tained only green or black precipitates, according to the
concentration of the sulphuretted hidrogen, and the quan-
tity of the sulphate of iron, presented to each other. If this
assertion of Mr. Thenard were a fact he observed, I confess
it is an anomaly, for which I cannot account, and which I
cannot reconcile with the whole of the facts I have related. “
If all these facts do not controvert the existence of the The existence
white oxide, I have still another to add, which not only 7 Gas tehs bape
controverts jt, but even renders that of the green oxide ieee
questionable.
Let a phial be filled with three parts of ammonia, and one
of sulphate of iron precipitating white; and let it be corked
immediately. At first, a white precipitate will be formed,
which on shaking the phial will dissolve in the ammonia. If -
the oxide of iron be afterward thrown down by means of
water or of an acid, it will always be green or aro and
if, instead of precipitating it by eens of these means, a
small curved tube be fitted to the phial, its extremity be im-
mersed in water, and sufficient heat be applied to expel the
ammouia; as this is volatilized, a black or brownish oxide
will fall down, which, on being dissclyed in muriatic acid,
will afford precipitates forthe most part red. Now it is im-
possible here to suspect a superoxidation by the ammonia.
Add to this, there are likewise salts of red oxide of 160N wri salts of
with excess of oxide, that are not only white and soluble iron with base
like the salt of Mr, Thenard, but frequently crystallize ; of red oxide,
that are not deliquescent, like the common red salt of iron ;
and that exhibit still ether peculiarities. I shall mention
these in a paper on another subject, where I shall speak of
iron incidentally. Tull that occasion, likewise, I shall deer
explaining the cause, why some of the white precipitates ob-
served by Mr, Thenard retain their colour even after long
boiling.
-
972
Effects of oxi-
genized muri-
atic acid,
On precipitat-
ing in a closed
phial, air is nut
absorbed but »
evolved. - ‘
’
Green oxide
offers three
questions to be
solved.
Proportion of
oxigen,
OXIDATIONS OF IRON.
boiling. The fact is very true, but oxigen has nothing to
do with it. |
The changes occasioned, according to Mr. Thenard, by
pouring oxigenized muriatic acid into a sulphate of iron pre-
cipitating white, agree very well with the idea I have formed
of this precipitate. As oxigenized muriatic acid is so little
soluble in water, and the sulphate of iron in question so
concentrated, it follows, that, if the acid be not very abun-.
dant in the solution, the precipitate will be green; because,
the little oxigen contained in the muriatic acid is capable of
converting to red oxide but a small portion of the green,
which i is $o pr edominant as to envelope the red, and prevent
its appearance. It will be the same to the eye as if the so-
lution were diluted with water, equal in quantity to the mu-
riatic acid, by which the white pr ecipitate would have been
changed to green ina similar manner. If, on the contrary,
the pein muriatic acid be very abundant, there is no
doubt, that the solutions will become red; as is the case with
all the green salts of iron.
With respect to the third fact, namely, that on making
the precipitate in aphial, and stopping it immediately, ab-
sorption takes place, and the residual air extinguishes a can=
dle, I shall only say, that instead of absorption, I have al-
ways found an evolution of air, which has sometimes forced
out the cork. It is true, that, after the white precipitate
has passed to green or red, the residual air sometimes extin-
guishes a iN ; but this is owing to the extrication of a
pel of which I shall speak presently.
Of the green owide,
The green oxide obtained by dissolving i iron in acids, of-
fered me three le ading facts to examine. Bint, to determine
_ how much oxigen. iron takes to pass to the state of green
oxide: secondly, to account for ‘its colour: thirdly, to ob-
serve the influence of atmospheric air on these solutions,
To determine the proportion of oxigen, and observe at ‘the
same time the influence of the atmospheric air, I took 90°
grains of iron filings, which I divided into three equal parts.
Fach of these x was dissolved amet in muriatic acid diluted
with
OXIDATIONS OF IRON. 973:
with water. As soon as the solution was complete, I preci-
pitated one portion of 30 grains by ammonia, washed and
drained it as quickly as possible, and dried it at a temperature
of about 120° [300° F.]. After it was dry I found it a brown Brown magne-
oxide, attracted by the magnet, weighing 362 grains, and tc oxide.
precipitated red from its solution im muriatic acid. Another
portion I precipitated likewise by ammonia; but with a view
to obtain the precipitate red, I diluted the solution with five
or six parts of water at 50° [144°] before I added the am-
monia. This oxide was in fact red; and when dried like Gis ond oot
the preceding, it was not at all affected by the magnet, magnetic. '
though it weighed only 36 grains. Lastly, I precipitated
the other 30 grains by ammonia likewise, using a very broad
yessel, in which I left the precipitate exposed to the air fora
month, stirring it twice a day. At the end of this time I The same.
dried it like the preceding: it was red, gave no signs of
magnetism, and weighed 36:2. The only difference be- Yet all equally
tween all these oxides was, that the first was brown and mag- sigan
netic, while the others were red, and did not become mag-
netic till exposed to a higher temperature.
Though I perceived im the course of this experiment, This does not
that it was not sufficient to establish with accuracy the pro- segs the
portion of oxigen, that the green oxide contains in solutions Seen cd
of iron by acids, on account of the oxigen that must combine = during solu.
with it during its being dried at so high a temperature, and
in a state of such minute division, it confirms two of the prin-
cipal results obtained im the oxides by calcination. This
process afforded me red oxides that had only °15 or °20 of
oxigen and the solution produced red oxides that contained
only *20 of oxigen, mcludimg what was absorbed during the
drying. Caicination afforded red magnetic oxides; and so-
lution did the same.
There are two methods of appreciating with extreme ac- Two methods
curacy the quantity of oxigen contained in the green oxide of doing this.
by solution. The first, which I should have preferred, if
circumstances had permitted me to adopt it, 1s, to dissolve a
given quantity of iron in muriatic acid, and carefully to col-
lect the hidrogen evolved; this measured, and for still far-
ther certainty burnt in Volta’s eudiometer, would give the
quantity of oxigen combined with the iron. The second is
to
’
B74 OXIDATIONS OF IRON.
to dissolve a given quantity of iron in muriatic acid,y-and,
after having precipitated it by an alkali, to dry it in an ex,
hausted receiver by means of a lens.
Influence of the air on solutions of iron.
a \
Oxigenation All the false notions diffused through the pneumatic
ergditeag theory of iron arise from having ascribed the colour and
ence ofthe other properties, that distinguish the green and red salts, to
salts. a difference of oxigenation, This difference once ésta-
blished as a principle, nothing was more natural, than to
refer to the same cause the transition of the salts of iron —
from green to red, on exposure to the air; particularly as
the cizcumstances, that sometimes accompany this preter:
menon, readily agree with this explanation. »
Mistake of ~ ‘The authority of Scheele gave additional weight to this.
Prhccle: illusion. This celebrated chemist had obseryed, that, on dis-
solving green sulphate of iron in water, a sediment of green -
oxide commonly remained; and hence he inferred, that it
was owing to the air contained in the water, which super-
oxided part of the green oxide; and this, becoming red, in-
creased its saturating power with respect to the acid, and
precipitated it, He then gave this process as a mean of
ascertaining the quantity of air contained in water. Great
as is the authority of this illustrious chemist, | must take the
hberty of observing, that, even were this phenomenon owing |
to a superoxidation by means of the air contained in the _
water, this mode of appreciating the quantity would not be |
c exact; because the quantity of precipitate does not depend
solely on the red oxide formed by the air, but rather on the
degree of acidity of the sulphate, which must always be supe
posed uniform according to Scheele’s theory, but this is cone
tradicted: by experience. Thus admitting the superoxiding
action of the air, a quart of water poured on a pound of very
acid green sulphate would let fall no precipitate; while a
quart ‘of the same water would throw down a considerable — |
quantity from another sulphate little or not at all acid,
Theairinthe Theexplanation of this phenomenon too is defective in
$Y ad hasno jtself, for it takes place equally whether the water contain
air, or be perfectly free from it. I made this comparative
. experi=
OXIDATIONS OF TRON. 275 :
experiment with two equal quantities of distilled water, from
one of which the air was completely expelled, while the other
was saturated with it artificially, and the results were the
same with both. Ifthe crystals of sulphate I used were white,
no deposition took place; but ifthey were green, a precipitate
fell down, which was equally bulky in both solutions: so
that Scheele’s process is calculated rather to show the aci-
dity of the green salts of irom to a certain point, than the
quantity of air in the water.
It maybe objected to me, that, from the experiments of as Gnanity
Dr, Carradori, boi'ed waiter always retains a little air: but, ee ir emwiaa
beside thatul have lately repeated the experiment with water must be far too
freed from air by Dr. Carradori’s method with the same hae
success, the experiments of Henry*, Humboldt, Gay Lus-
sac, and more especially of Dalton}, on the absorption of
gasses by water, completely terminate the controversy. Ac-
cording to Dalton, to whom I refer because he more directly
tyrned his attention to this point, water saturated with at-
mospheric air contains only 2-012 per cent of its bulk, of
which +778 are oxigen gas, and 1°234 nitrogen. Conse-
quently 160 cybic inches of water contain about + of an inch
of oxigen. Now if we consider, that the greater part of this
gas is expelled by boiling; and if besides we make a correc-
tion for the heterogeneous substances, which according to
Lambert and Saussure the air always contains, we shall find
the influence of the oxigen contained in the water, even sup-
posing it saturated ach it, must be nothing; for if a green
salt of iron with excess of oxide be thrown into 100 cubic
inches of water at 60° [167° F.], a precipitate of at least 15
_ or 20 grains of red oxide will be formed, which cannot be
i "attributed to the oxigen of the air contained in the water, un-
less the experiments of the learned natural philosophers I
have quoted be altogether futile. =
1 Beside this experiment; beside the ammoniacal solution Proofs that the
a of green sulphate, which passes to red without the possibi- = oe api
lity of suspecting the presence of oxigen ;. beside the precipi- lutions of irore
tate, which did not increase its oxigenation 1 per cent by
{ * Philosophical Transactions for 1803, or oar Journal, Vol. V. p. 22%
MG Manchester Mem, X YS, Vol. 1, or Journal, Vol. XHI. p. 291,
exposure
2:76 OXIDATIONS OF IRON.
exposure to the air for a month; I have made several other
experiments tending to the same object: and they have all
convinced me, that the air has no superoxiding action on
solutions of iron, at least at the common temperatures. | Of
' these I shall recite only two, that are among the most cony
clusive.
1. I dissolved two equal portions of iron under circum-
stances perfectly similar. One of the solutions I put mto a
glass three inches in diameter, and immersed in it a curved
tube, the extremity of which was a ball pierced with several
holes. Throughthese | passed atmospheric air for seven hours
at different times. At the expiration of three days, I com-
paréd thése two solutions in various ways, and found, that the
one into which I had forced air was perfectly similar to the
other, which was not perceptibly altered, though the tempe-
rature was 12°[59° F.]. 2. By means of the same apparatus
I passed about three quarts of oxigen gas through a solution
of ten grains of iron, and, though the temperature was 25%
[gs°4 F,], it had no action on the solution.
Farther proofs,
On the'colour of the, green oxide.
Particles of On adding a few drops of alkali to a solution of iron a
ns little diluted, I observed, that every particle of thé oxide
hollow spheres Was formed of a very thin pellicle, including some fluid, and
oar 4 J accounted for the green colour by the difference of density
LK between this pellicle and the fluid it enclosed. I likewise
This might ac- ascribed the alteration in green solutions exposed for some
count for their days to a temperature of 20°[77° F.] to the bursting of these _
oe ani? vesicles by the dilatation of the fluid contaimed in thenr
cases, ‘To the pressure exerted upon these vesicles I attributed the
unehangeableness of these solutions in bottles quite full and
but notin _— clase stopped. But I could not reconcile with these modes
athens: of viewing the subject the change, that is induced in green
solutions of iron by oxigenized miuriatic acid, and in red so», q
lutions by sulphuretted hidrogen. The nature of the con« |
stituent dpliichict of these tw ovreag ents renders the manner —
eis had T not vee Sumi by all the facts I have re- |
lated, 9
|
‘
Fi
two substances were the same, that they were magnesia, and
lar to the green oxide of iron*. These precipitates exposed
OXIDATIONS OF TRON. 277
télated, that oxigen has no influence in the red or green co«
lour of oxides ofiron. I meditated some experiments there-
fore, tending to observe the mode of action of these two
reagents, when I recollected a fact observed at the beginning
of my inquiry, which thus indemnified me for a number of
errours, into which it had led me before.
In every kind of iron I had hitherto treated I found a sub- White precipi
stance, that fell down ina white precipitate, did not change *t¢ fom irom.
by exposure to the air, gave an emerald green precipitate
with prussiate of poiadh, and which I believe to be what ee
Bergman called siderite, rather than phosphate of iron. On He ;
the other hand [ obtained from some red salts of iron a white
precipitate, that sometimes crystallized in laminze very soft to ‘roe aee
the touch, which the most experienced mineralogist would tites.
take for French chalk, but which is nothing bit a salt of
iron with excess. of oxide. I thought at the time, that these Both imagined
o be magnesia.
that this was nothing but iron ata maximum of oxidation.
The name of this earth favoured the illusion; as did the Opi-
nion of former chemists respecting the transmutation of me-
talsinto earths. I deferred the vestigation of this subject
-4o a future period, making in the mean time only a few -ex-
periments on magnesia; and I found, that, on treating solu-
‘tions of this er sulphuretted hidrogen, it alferded Sulphuretted
hidrogen preci-
a precipitate similar to the green oxide of iron. pitates magne.
Though my farther reserches concerning iron taught me, sia green,
that neither of these substances was magnesia, the way in
which this earth was coloured by sulphuretted hidrogen was
“a fact, the reason of which I intended to make the subject
ef future inquiry ; and which, on recurring afresh to my me-
‘mory, led me to suspect, that sulphuretted hidrogen might
‘have a mode of action different from any with which we were
acquainted. Iwas eager to repeat this experiment, not only
on magnesia, but on lime and alumine likewise, and I found abpriahova
in fact, that the soluble salts of these three earths, treated
‘by sulphuretted hidrogen, gave precipitates altogether simi-
to
* Certain management is necessary, to succeed in this experiment,
pwhich Ihave not repeated often enough, to be able to give certain in-
struction
278
The green co-
Tour goes off by
exposure (oO
the alr.
These green
precipiiates are x
hidrurets.
The green ox-
ides of iron are
the same.
Oxigenized
muriatic acid
takes away
their hidrogen.
The presence
of hidregen in
the green ox-
OXIDATIONS OF IRON:
to the air resume their white colour after some time, if they
be not shaken: but agitation greatly accelerates this change,
which is another similarity between these precipitates and
those produced from the red salts of iron by sulphuretted
hidrogen,
These green and ear thy precipitates are not hidrosulphu-
ets, as might be supposed; but hidrurets, which probably
retain a little acid. This is proved by their bemg decom<
posed by oxigenized muriatic acid, without leaving any
traces of sulphur; and by retaining their greea colour, and
other properties annexed to it, when redissolved in acids;
which could not be the case if they were hidrosulphurets,
since acids decompose these instantly.
From these elucidations the cause of the green colour of
oxide of iron, and its colouration by muriatic acid, suggested
itself as it were spontaneously. The green oxide is never
formed, unless hidrogen be set free: a part of this therefore
remains engaged in re oxide, and imparts to it the green co<
lour, with the property of being less soluble in water, or more
crystallizable. This property of renderimg a salt more crys-
tallizable, possessed by a principle of so little density, ap=
pears at first sight inconsistent; but it is-confirmed by the
superoxigenized muriate of potash, which is renderedtwo or
three times less soluble than the simple muriate by the addi-
tion of oxigen. F
Oxigenized muriatic acid then acts on a green salt of iron,
as it does on sulphuretted hidrogen, phosphorus, &e.. bt
deprives the oxide of the hidrogen with which it is combined,
as it does the sulphur and the phosphorus: which at the
same time proves, that in the oxide of iron it-is not in the
samé state of dilatation as that in which we are acquainted
with it uncombined, for in this state it does not combine
with oxigenized muriatic acid at the temperature of the at-
mosphere.
The Indrogen likewise betrays itself in the offensive smell
given out by a concentrated solution of iron, when a fixed
structions respecting it. Ehave left sulphuretted hidrogen in contact
with sulphate of magnesia for au hour before it precipitated. Sometimes
be
the precipitate is green in the very act of falling down, at other times if
does not become green till some moments after,
alkali
DY
Br,
OXIDATIONS OF-IRON.
ulkali* is added to it, and the glass shaken a little: and we
eannot allege, that this smell is owing to a few globules of
hidrogen, that have remained mechanically entangled in the
solution, since the same phenomenon takes place, if the so-
lution be previously boiled. Ifthe solution be diluted with
six or eight parts of water at 50° or 60° [144° or 167° Eds
and it be stirred with a glass rod as the alkali is put in, the
smell is still very strong, and continues to exhale as. long as
an atom of green oxide remains iu the precipitate; so that it
is easy to tell by this, without seeing the precipitate, whe-
ther the solution be red or green. _ When a little green sul-
phate of iron in a very concentrated solution, like that which
gives a white precipitate, is precipitated in a phial, and this
is corked and shaken, it will be seen, that the volume of
gas is increased ; for, if the cork do not fit very tight, it will
be forced out, notwithstanding the temperature continues
the same. If the air in the phial be afterward examined, it
will be found sometimes to extinguish a candle, or to deto-
nate on its application. Now both these are compatible with
the presence of hidrogen, according as it is pure or mixed ;
and possibly there may be a litle iron dissolved in it, as zinc
or arsenic sometimes is.
7 Te satisfy myself still farther cf the presence of hidro-
gen, and its influence on the salts of iron, I adapted to a
tubulated retort a small receiver, and to this a curved tube,
the extremity of which opened under a jar in the pneumatic
apparatus, Into the retort I poured a solution of green sul-
phate of iron recently made, having previously boiled it half
an hour, to prevent any suspicion of hidrogen mechanically
retained in it. This solution I precipitated with caustic
soda greatly diluted with boiling water. As soon as the
mixture was bronght to boil, a gas fetid as hidrogen was
evolved, which detonated on the contact of fame. The
water of the pneumatic apparatus too had the nauseous
taste and smell of hidrogen disengaged from solutions of
iron. {
In order to expe! cli the hidrogen, or to convert all the
‘exide from green to red, I continued the distillation,
* If ammonia be used, its smehl conceals that of the hidrogen.
Scarcely
279
ides of iron
proved by the
sincll,
and by the gas
evolved.
Faither proaf
by expelling
the hidrogen.
280 , OXIDATIONS OF TRON.
Scarcely was the mass dry, when the retort burst, and I
found in it more than 300 grains of red oxide, with a little
green oxide, which occupied the bottom of the retort. The
pressure of the ret oxide and sulphate of soda, by which
the green oxide was covered, had prevented the disengage-
ment of the hidrogen from this portion.
Proof that In support of my opinion T° shall add two facts, which,
a : though less direct than those I have already given, are of
acquire more considerable weight. When oxigenized muriatic acid is
pe tear poured on a green solution, if the oxigen of the acid com-
mutiatic acid. bined with the oxide of ivon, a cousiderable extrication of
caloric must take place, in consequence of its more dilated
state in the acid, and more condensed or fixed state in the
oxide, from which the greatest heat of our furnaces cannot
expel an atom. - But I convinced myself by several experi- :
ments, that the increase of temperature is scarcely percepti-
‘ ble. This slight evolution of caloric is consistent with the
combination of the hidrogen, given out by the hidruret of
iron, and the oxigen from the muriatic acid, because in both
these combinations the gasses are nearly in the same state of
- dilatation as when they form water.
Proof that sul- Lastly, if the action of sulphuretted hidrogen on a ve
bide 2 solution of iron be merely to bring it back to the same de-
not deprive it gree of oxidation, as that in which the common green, solu=
of oxigen. —_ tions are, the properties of both should be the same. On
the contrary, the solutions rendered green by sulphuretted
hidrogen rapidly change red on exposure to the air; and
heated for a quarter of an hour they become entirely red :
which is not the case with the common green salts recently
made.
(To be concluded in our next.)
MN nistlls Fo
Hit
; 2 : (re
Naholsons Philos. fowmnedl VoLNV,. AVI, p 281
- 2 > , Pam}
: Ue "Outtwcveds Viell He
WOU".
?
?
?
C
Ho
CPC
?
WEED HARROW. 281
Ve
Account of Mr. Curwen’s Drill Horse Hoe, or Weed
Harrow.*
SIR,
As one great and most important advantage of drill hus. Advantage of
bandry Proceeds from the opportunity of cleaning foul drill husbandry,
grounds, as also of breaking and loosening stiff soils, to
give the power of extension to the roots of grain; what.
ever can facilitate these operations, will, I flatter myself,
be deemed worthy of the attention of the Society.
Having hitherto found great difficulty and much labour Difficulty of
necessary in accomplishing the cleaning of wheat and other Cleaning from
grain, I have been led to make some experiments, and Iam —
_” sanguine in my hopes, that the harrow I send for the in-
Spection of the Society will be found to accomplish the purs
pose with greater ease and facility, than any thing at pres
sent in use.
The simplicity and ease, with which it is worked, have en- Harrow for this
abled me, this season, to give my wheat crop, which exceeds Purpose.
one hundred acres, two cleanings, and at an expense of some«
what less thana shilling per acre each operation; aman and
boy, with one horse, being able to clean above seven acres
aday. The direction of the harrow, to prevent its in-
juring the grain, is effected by an alteration of the chain, by
which it is attached to the wheels. The distance of the
teeth from the centre tooth must be regulated by the width
of the drills. In case they exceed a foot, the harrow should
be broader, to admit of another row of teeth. To clean at
mine inches, two inches and a half are allowed on each side
of the centre tooth, by which means every part of the earth
is cut between the rows of grain. The size and strength
of the teeth must be regulated by the nature of the soil.
The thing is so simple, that I hesitated laying it before the
Society, till I was encouraged by persons, whose experience
and knowledge are infinitely greater than my own. ;
The complete introduction of drill husbandry would, I Drill husbandry
conceive, be of great national importance, and under this "ommended.
* Transactions of the Society of Arts, for 1806,
Vor, XVII.—Aveusr, 1807, U cons
282
London, May 5th, 1806.
Explanation of
the plate.
‘the corn. ‘These knives are strong, and have a sharp edge
- positions of thedouble rows of the knives, and of the space
The harrow
clears all the
weeds,
+ ;
WEED HARROW.
conviction whatever can facilitate its operations may not’
be unworthy of attention, and will, I hope, excuse the
liberty I have'taken.
I have the honour to be, Sir,
LORY obedient humble Servant,
J. C. CURWEN.
Explanation of the Engraving of Mr. Curwen’s Drill Horse-
Hoe, or Weed Harrow. Plate VIN. Fig. 1, 2.
Fig. 1. shows the carriage, within the shafts of which, A,
the horse is placed: the carriage wheels are intended to be
half the width of the butts or stitches, so that once going
up, and once returning, will be sufficient to clear each butt
from weeds. ;
B, The hoe, or harrow, which is attached to the car-
riage by the chains C C, The harrow may be raised higher,
or sunk lower, or placed more on one side or another, as
occasion may require, by altering the position of the chain,
as will appear by an inspection of the plate.
DDD DDD, Six double rows of teeth, or knives, which
are so placed in the frame, that each double row may pass
up the interval betwixt the rows of corn, and cut or pull
up the weeds, that grow in such intervals, without injuring
in front. 4
EE Are the two handles, by which the person who holds
them may direct the knives, or teeth of the harrow, to pass:
in straight lines up the intervals.
Fig. 2. shows the underside of the weed harrow, that the
left to prevent the corn being injured, may be more clearly
seen.
Certificates in Favour of Mr. Curwen’s Harrow.
At the request of J. C. Curwen, Esq., 1 beg leave to
state, that I have been present, when Mr. Curwen’s harrow
for cleaning drilled corn has been used, and have worked a ~
little with it myself; that its effect appeared to me most
highly beneficial in clearing away in the spring all the
weeds,
WEED HARROW. . 283.
weeds, that had grown during the winter among the wheat,
without the least injury to the grain; and also in raising raises the en
up the top soil, which had become sad and heavy, and thus
enabling the spring shoot to take root more easily: and at covers the roots
the same time it covers the roots of the corn with fresh soil, pelle his
which are often left quite bare by the washing of the sais
in winter, and so subject to be killed by the frost. It also
enables the farmer, to sow his barley much earlier than he
could broad-cast, as it will both clear the corn preyious to
sowing the grass seeds, and afterward harrow them in. and harrows in
Its utility in every respect appeared to me so very great, "5 seeds.
that 1 was induced to adopt the plan of sowing my corn
with the drill upon my fallows this spring, and have ac-
cordingly got a harrow made upon the model of Mr.
Curwen’s.
I have the honour to be, &c.
J. D. B. DYKES.
Dovenby Hall, May 13, 1806.
SIR,
We whose names are hereunto subscribed do certify, that
we have paid particular attention to a harrow, made use of
in the farm of J. C. Curwen, Esq., for the purpose of
harrowing between the rows of driiled grain. We conceive
it of great utility; the expedition is undeniable, as upwards
_ of seven acres can be done with ease in eight hours, with
enly a boy to lead the horse, and aman to regulate the
harrow.
Weare, Sir,
Your most obedient humble Servants,
Tuomas Garr, Merchant, Workington Hall Mills.
Martruew Foster, Farmer, at Calva, near Workington.
Workington-Hall, May 19, 1806.
U2 VI. Account
Drilling turnips
decidedly__pre-
ferable to broad-
cast,
Hoe harrow for
turnips and
other wide
drilled crops.
Its use.
Near Barnard
Castle turnips
drilled at 27
inches.
DRILL HOE HARROW.
VI.
Vercen
Account of a Drill Horse Hoe for Turnips, shmentianicated
by Mr. Cuarvtes WatstTELL.*
I consequence of the premiums, which the Society of
Arts has offered, and bestowed for several years, on the
comparative culture of turnips, the drill practice has ap-
peared so decidedly superior to the broad-cast method, that
they have thought it unnecessary to continue them, At the
same time they have given a figure and description of a use-
ful drill hoe and harrow, with which they observe they
shall probably finish the subject, and which therefore we
shall lay before our readers nearly in Mr. Waistell’s words.
Dear Srr,
I wave ordered a new agricultural implement to be left
for a short time at the Society’s Repository for inspection.
It is called a hoe harrow, and is, as its name imports, a hoe
and harrow combined. Fordestroying the weeds, and pul-
yerising the soil in the intervals of drilled turnips, and of
other crops drilled sufficiently wide to be horse-hoed, [
know not of any other implement of equal efficacy.
It enables the farmer to cultivate those intervals as com<
pletely as a well wrought fallow, so long as the horse can
travel therein, without injury to the growing crop. I know
not who the meritorious inventor is. The first I saw was
a few years ago at West Park, near Barnard Castle.. This
was brought from Carlisle ty my brother, and many have
been made from that pattern, and are now in use, and are
highly approved of by farmers in the neighbourhood of
Barnard Castle, where the turnip crops are now generally
raised in drills about 27 inches apart. ‘This mode was first
introduced there about 23 years ago, before which time they
were all sown broad-cast.
An implement of husbandry, possessing such superior
utility, as this hoe harrow seems to me to possess, is desery=
ing of being made knownas generally and as speedily as pos-
sible. I conceive this would be best effected through the
* Trang, of the Soc. of ‘Arts for 1806,
medium
DRILL HOE HARROW. ORY,
medium of your respectable Society, to whose notice I must
entreat you to have the goodness to introduce this imple-
ment. Should they concur in opinion with me respecting
it, Iam persuaded, that they will give a plate and descrip-
tion of it in their next volume.
Convinced, that the fertility and productiveness of our Horse hosing ”'
arable grounds may be much increased by a more ge- 'ecommended.
neral practice of the horse-hoeing husbandry, I wish to :
see the practice of it advanced more nearly to perfection, as
that must tend to promote its more general adoption.
hie] Iam, Dear Sir,
Your very humble Servant,
CHARLES WAISTELL.
No. 99, High Holborn.
Explanation of the Engraving of Mr. Waistell’s Drill Horse
Hoe Harrow, Plate VIN. Fig. 3.
Fig. 3. shows the hoe harrow, to which the horse is to be Explanation of
ditached by the upright iron a, in which are a number of ‘* Plate.
holes, to admit the drag chain to be put higher or lower, as
may be found necessary. This iron is at one end fixed
- firm in the fore part of the machine at 5, and at the other
end to the farther side, or wing, c
d, Is the nearer side or wing of the machine, and mova-
ble by a joint at e. This wing may by this mean be ex-
panded or contracted, as the interval between the rows to
be cleared of weeds may require. |
- f, A strong wedge-like tooth in the fare put of the
machine, to tear up the weeds, which are deep in the
ground.
| g, g, Other teeth more slender, fixed in the two wings
or sides of the machine, and also intended to tear up weeds
and loosen the earth.
h, h, h, Three triangular hoes. That which is in front
has a strong iron fixed in its centre; the two ‘others at the
‘hinder part of the machine have the irons fixed at the far-
ther corner of each. The intent of the centre hoe is to cut
off the weeds in the middle of the interval; and of the other
“two, those on each side next the crop, and to lay all the
weeds in a ridge-like form in the middle of the be | to dry
Sand “rot,
i, 7, The
| 286 ON CAPILLARY ACTION.
#, i, The two handles, by which the machine is managed.
k, A slender iron bar, with a peg and holes to direct the
distance of the expansion or contraction of the machine.
2, A strong iron vice, which works in a grooved iron,
fixed to the inner side of ‘the wing d, and which, when
screwed down, holds the machine firm at the distance of
expansion wanted for use.
Fig. 4, Shows on a larger scale one of the hinder hoes
separate from the machine, and the manner by which it may
occasionally be raised or lowered’ in the machine by a pin
_and holes.
VI.
On Capillary Action. By Mr. Larvacr.* —
Results of capil: IDY considering the theory of capillary action in a new
pe Race fae point of view, I have not only succeeded in simplifying it,
but in generalizing the results, to which I had been led be-
fore by analysis. I had determined the elevation or depres-
sion of fluids only in circular capillary spaces, and between
Determined for planes: but I shall here proceed to determine them, what-
spaces of any h h h t fth
figure, and for €Ver these spaces may be, or whatever the nature of the
any number of surfaces by which they are included ; supposing even in these
fuids. .
spaces auly number of fluids placed one above another; and
I shall thence deduce the increase or diminution of weight,
that bodies plunged in fluids undergo by capillary action.
Affinities of ‘The combination of these results with those I have found
substances to | ; ‘
Bier deicak by analysis has given me an gone expression of the afi.
from their re- ities of different substances to fluids, by means of experi-
hep gs +o sepa~ ments made on the resistance, that disks of different~sub-
stances, applied to the surface of fluids, oppose to their
separation. I dare venture to believe, that this will throw
great light on the theory of affinities; for what, I advance is
_ founded on geometrical reasonings, and not on vague and
precarious considerations, which ought to be strictly ban-
ished from natural philosophy; unless, imitating Newton
in his Optics, we give them mercly as conjectures calculated
* Journal de Physique, Vol. LX. p. 474, Dec. 1806.
to
@N CAPILLARY ACTION. 287
to guide us to farther searches, but leaving the merit of dis-
covery almost wholly'to him, who shall establish them on
solid foundations by observation or analysis.
T intend to publish without delay, in a supplement to my Supplement to
Theory of Capillary Action, the analytical demonstrations the Theory of
‘of the theorems, which I have only mentioned iv different Binet peligauas
promised.
‘numbers of this Journal.. At the same time I shall give a
new method of arriving at the fundamental equations of this
‘theory. From these equations I shall deduce the general
theorems, which I am now about to lay before.the reader,
demonstrating them by the direct consideration of all the
forces, that concur in the production of capillary effects.
At will appear, that the forces, on which these effects des Forces on which
pend, do not stop at the surface of fluids; but that they ae cue
extend through the whole of their interior, and even to the confined popes
extremities of the bodies immersed in them; which. esta- Soa
blishes the complete identity of these forces sith affinities. : Gare,
‘If we.conceive any kind of prismatic tube, in a verti: Theorem.
‘ cal position, with its inferior extremity immersed in a fluid
of indeterminate quantity ; ; the volume of fluid within,
raised above the level by capillary action, is equal to. the
circumference of the interior base of the prism, multiplied
hy a constant quantity, which is the same for all prismatic
tubes of the same matter immersed in the same fluid.”
.» To demonstrate this theorem, let us imagine, at the infe- Demonstration.
_rior extremity of the tube, a second tube, the infinitely thin
Sides of which arc the prolongation of the interior surface
of the first tube, and, having no action on the fluid, do
not prevent the reciprocal attraction between the molecules
_of the first tube and the fluid. Let us suppose, thatthe se-
cond tube is at first vertical, that then it bends horizontally,
and that afterward it resumes its vertical direction, retain-
ing the same figure, and the same size, throughout its whole
extent. Itis evident, that, while the fluid is in equilibrio,
the pressure in the two vertical branches of the canal formed
_ by the first and second tube will be the same. But, as there
_is more fluid in the first vertical branch formed of the first
4 .tube,and part of the second, than in the other vertical
branch, the excess of pressure, that results from this, must
be peer by the attractions of the prism and the fluid
| for
Attractions to- .
ward the bot-
tom of the tube’
Forces acting
on the fluid in
the tube,
ON CAPILLARY ACTION.
for the fluid, contained in this first branch. . Let. us.analyse
these different attractions with care, and first consider those
that take place.taward:the lower part of the first tube...
For. this let us conceive, that the base of the tube is ho.
rizonta]. The fluid contained in the second tube will be
attracted vertically toward the bottom, Ist by itself, 2dly,
by the fluid surrounding the second tube. But these two
attractions are destroyed by the similar attractions, that the
fluid contained in the second vertical branch of the canal exs
periences near the surface of the level of the fluid. Ac.
cordingly we may leave them. out of consideration here.—
The fluid in the first vertical branch of the second tube will
also be attracted perpendicularly upward by the fluid in the
first tube. But this attraction will be destroyed by the at-
traction it exerts on the latter fluid: these two reciprocal
attractions therefore may be set aside. Lastly, the fluid in
the second tube will be attracted perpendicularly »pward
by the first tube, and hence this fluid will have a vertical
force, which we shall denote by Q, that will. contribute - to
destroy the excess of pressure owing to the elevation of the
fluid in the first tube.
Let us now examine the forces, ith which the fluid in
the first tube is actuated. In its lower part it experiences
the following attractions: Ist, it is attracted by itself; - but
the reciprocal attractions of the particles of a body impress
upon it no motion, if it be solid; and we may conceive the -
fluid in the first tube to be consolidated, without any dis-
turbance of equilibrium. Q2dly, This fluid is attracted by
the fluid in the interior of the second tube: but we have seen,
that the reciprocal attractions of these two fluids destroy
each other, and must not be taken into account. 3dly, It
is attracted by the exterior fluid, that surrounds the second
tube; and from this attraction results a vertical force acting
downward, which we shail denote by —Q’. We prefix to
this the sign —, to indicate, that its direction is contrary to
that of the force Q. We shall observe here, that, if the
laws of attraction relative to the distance be the same for
the molecules of the first tube and those of the fluid, so that
they differ only in respect to intensity ; if we nominate these.
intensities in equal volumes ¢ and ¢’, the forces. Q and Q are
| 3 proportional
ON CAPILLARY “ACTION. 289
proportional to e and ¢’: for the interior surface of the flaid
surrounding the second tube is the same as the intérior sir.
face of the first tube, so that the two masses “differ only in
their thickness. Butas the attraction of masses becomes ~* *
imsensible at sensible distances, the difference in their thick. . ry
nesses can produce none in their attractions, provided these
thicknesses be sensible. 4thly, and lastly, The fluid of the
first tube is attracted vertically upward by this tube. - “In
fact let us conceive this fluid divided into an infinite number
of little vertical columns: if we draw a horizontal’ plane
through the superior extremity of one of these columns, the
part of the tube below this plane will produce no vertical .
force in that column. No vertical force will be produced
therefore, but what is owing to the part of the tube above
the plane; and it is evident, that the vertical attraction of
this part of the tube for the column will be the same as that
of the whole tube on an equal and similar column placed
in the second tube. Thus the whole vertical force pro-
ducéd by the attraction of the first tube on the fluidit contains
will be equal to that, which the attraction of this tube pro-
. duces on the fluid contained in the second tube: this force
therefore will be equal to Q.
‘On combining together all the vertical attractions expe- Vertical force
rienced by the fluid contained in the first vertical branch of acting upward.
the canal, we shall have a vertical force directed upward,
and equal to 2 Q—Q’. This force must balance the excess
of the pressure arising from the weight of the fluid raised
above the level. Let V be its volume, D its density, and ¢
its specific gravity, ¢ Dx V will be its weight. Thus we
shall have g Dx V=2 Q-—.
' Now attraction being sensible only at imperceptible dis- The base may
tances, the first tube acts sensibly only on columns extremely 0° masacredss
near to its sides: we may neglect the curvature of these sides
therefore, and consider them as developed on a plane sur-
face. The force Q will be proportional to ‘the magnitude
of this surface; or, which comes to the same thing, to the
cireumference of the base of the interior surface of the pa-
rallelopipedon. ‘Thus, if we call this circumference c, we
shall have Q=exc; ¢ being a constant proportional to the
intensity of the attraction of the matter of the first tube for
i the
290 ON CAPILLARY ACTION.
the fluid. We shall also have Q’=e'xc; ¢! being propor-
tional to the intensity of the attraction of the fluid for it-
(2e—¢') xc.
| gD
pression of the theorem to be edu betel:
—e
x D
of the observed elevation of the fluid in a very narrow cy-
lindrical tube. Let q be the height, to which the fluid rises
in this tube, and Z the radius of its cavity: putting +for the
semicircumference of which the radius is unity, we shail
have nearly V=rx1*q, c=2/ 7: the preceding equation
Zee)! lq
xD Fig 3 and consequently we shall
self. Therefore V= > which i is the algebraic eX-
2 ;
The constant quantity ~ : may be determined by means
z sath
then will give
h V = — °
ave sae
If e’ exceed 2e, g wil! be negative; and consequently,
the elevation of the fluid changing to dep b Sibu V will be
negative.
Let us put / for the mean height of all the fluid columns,
that compose the volume ’, and b for the interior base of
the parallelopipedon: then we shall have V=hb, and con-
wb g Xi te
sequently h = a
Proportions of When the bases of different parallelopipedons are similar
bases, if similar figures, they are proportional to the squares of their ho-’
figures.
mologous sides, and their circumferences. are proportional
to these sides. :
Hf emily pole If these bases be regular polygons, they wall be equal to —
gons. the products of their circumference multiplied into half the
radius of the inscribed circle: the heights h therefore will.
be reciprocals to these radii. Denoting these radii by r,
we shall have h Dieed
gry 2
A squareanda Thus supposing two equal bases, one of which is a square,
ree and the other an eters triangle; the values of r will ©
be to each other as 2 to 3%, or nearly as 7 to 8. ;
The law con- Mr. Gellert has published some experiments on the ele- ‘
ie on ce vation of waterin rectangular and triangular prismatic tubes | : |
ON CAPILLARY ACTION. 29]
of glass, in the Memoirs of the Petersburg Academy, vol.
XII. These confirm the law, according to which the
heights are reciprocals to the homologous tines of similar
bases. Mr. Gellert farther conclades from his experiments,
that the elevations of a fluid are the same in rectangular and
triangular’ prisms, the bases of which are equal. But he
admits, that this is not so certain as the law of the heights
being reciprocal to the homologous lines of similar bases.
Tn fact it has just been seen, that there is a difference of an
eighth between the elevations of the fluid in two prisms,
the bases of which are equal, and one of which is a square,
the other an equilateral triangle. The experiments related
by Mr. Gellert do not afford sufficient data, to compare
their results exactly with the preceding theory.
‘If the base of the parallelopipedon be a rectangle, the A narrow paral-
Jarger side of which is equal toa, and the other side, sup. '*!s"™-
posed very smal], equal to /, we shall have b=al, andc=
lqgx (tat+21) =ax (1+2) 3
‘2QatQl: ty he
a consequently h oul
T ~
-and by neglecting — we shail have h=q, agreeable to ex-
perience.
*¢ Tf the indefinite vessel, in which the parallelopipeden Where several
is immersed, include any number of fiuids placed horizon- ae gaa
tally one above another; the excess of the weights of these
fluids contained in the tube, over the weight of the fluids
which it would have contained without capillary action, is
the same as the weight of the fluid that would rise above the
Jevel, if the vessel contained only that fluid in which the in-
_ ferior extremity of the parallelopipedon-is immersed.”
In fact, the action of the prisms and this fluid on the
same fluid included in the tube, is evidently the same as in
the Jatter case. The other fluids contained in the prism
being raised sensibly above its base, the prism has no action
on either of them to raise or depress it. As to the recipro-
eal action of these fluids on one another, it would evidently
be destroyed, if they formed a solid mass together, and this
‘we may suppose without any disturbance of equilibrium.
we Ie the :vessel contain -but two fluids, in which the Case of tia
prism is entirely immersed, so that its superior part is in age
one
909° ON CAPILLARY ACTION.
one fase and its inferior in the other; the weight rm ‘the.
lower fluid, raised i in the prism by capillary action above its
Jevel in the vessel, will be equal to the weight of a similar.
volume of the upper fluid, plus the weight of the inferior
fluid, that would rise in the prism above the level, if. there
were no. other fluid in the vessel, minus the weight of the.
superior fluid, that would rise in ie same prism aboye the
level, if the vessel contained this fluid only.”
Demonstration. . To demonstrate this, it isto be observed, that theaction
of the prism on the portion of the inferior fluid it contains
is the same as if this fluid only were in the vessel: in both
these cases then this fluid is drawn perpendicularly upward
in the same manner, both by the attraction of the prism,
and that of the fluid that surrounds the lower. part of the
prism; and these attractions united are equivalent to the
weight of the volume of this fluid, that would ascend in
the prism above the level, if it were alone. in the vessel.
In Jike manner the superior fluid, contained in the upper
part of the prism, is drawn perpendicularly downward by
the attraction of the prism and the fluid that surrounds
this part, as it would be drawn downward by the same at-
tractions, if the vessel contained only the superior fluid ;
and these attractions united are equivalent to the weight of
the superior fluid, that would then rise in the prism above
its level in the vessel. Lastly the column of fluids within
the prism, which is above the level of the inferior fluid in
the vessel, is drawn perpendicularly, downward by its own
weight, and perpendicularly upward .by the weight of a
similar column of the superior fluid. On combining all
these forces, which must counterbalance cach other, we
shall have the theorem just announced. By the same prin-
ciples we may determine what will takeplace, when ahollow
prism is entirely immersed in a vessel filled with any number
of fluids. ane pea
Where the base In what has been said the base of the prism was supposed
path oe itr to be horizontal: but if it were inclined to the horizon,
the yertical aciion of the prism on the fluid w ould still be
the same. For a plane.of a sensible thickness, having its
lower part, the surface of which is terminated by a “Tight
Jine inclined to the horizon, immersed in ‘a fluid, “attracts
this
ee
ON CAPILLARY ACTION. 293
this fluid parallel to tis surface, and perpendicularly to the
right line that terminates it, proportionally to the length’
of this line: “but this attraction, resolved into a vertical:
force, is proportional to the horizontal magnitude of the
plane. Hence it is easy to conclude generally, that, what"
ever be the figure of the base of the prism, its vertical at-
traction, and that of the exterior fluid on the fluid included
in it, are the same as if the base were horizontal. The
first theorem therefore will hold generally, if we under-
stand by the circumference of the interior base that of the
interior section, perpendicular to the sides of the prism.
6 If the prism, the lower part of which is immersed The volume of
in a fluid in a vessel of indefinite size, be inclined to the ea
_ horizon, the volume of fluid in the prism raised above the in the inverse
level of the fluid in the vessel, multiplied by the size of the ee Or eenie
angle of inclination between the side of the prism and the tion,
horizon, will be constantly the same, whatever this incli-
nation may be.”
Th fact, this product expresses the weight of the volume
of fluid raised above the level, and resolved into a force
parallel to the sides of the prism: this weight, thus resolved,
must balance the attraction of the prism and the external
fluid to the fluid it contains; an attraction evidently the
same, whatever may be the inclination of the prism ; therc-
fore the mean perpendicular height of the fluid above the
devel is constantly the same.
«© Tf a parallelopipedon be placed perpendicularly in Ascent of afiuid
between two pa-
another parallelopipedon of the same material, and their zallelopipedons
inferior extremities be immersed in a fluid; putting V for of the same ma-
the volume of fluid raised above the level in the space in- ak.
cluded between the two parallelopipedons, we shall have
ig: ; _
V= x (e+<) = x (¢ +e’) 5 ebeing the
inner circumference of the base of the larger parallelopi-
pedon, and c’ the outer circumference of the. base of the
“smaller.”
~ This theorem is demonstrable in the same manner as the Demonstrated.
first. If the bases of the two parallelopipedons be similar
__ polygons, ‘the homologous sides of which are parallel, and
placed ail at the same distance, if we put / for this distance,
| the
O04 ON CAPILLARY ACTION.
the base of the space the two parallelopipedons leave be~
I Ba
tween them will be vere thus, h being the mean
(ce)
2
height of the fluid raised, we shall have V=h 1x , and
consequently h=q. Wemay determine too from the pre-
ceding principles what will take place, if the prisms be
immersed wholly or partly im a vessel filled with any num-
ber of fluids, and in the case of their being inclined to the
horizon.
Where they are ‘* The data being the same as in the preceding theorem,
pari if the two paralielopipedons be of different materials, put-
for the fluid, and e, for the attractive force of that of the
ao / _
as yo SO xe
so that, if we put q and q , for the elevations of the fluids
in two very narrow cylindrical tubes of the same interior
radius 7, formed of these two materials respectively, we
shall have V=7/x (qce+9, c.”’)
This theorem too is demonstrable in the same manner as
the first. It is easy to perceive, thai by the same _princi-
ples we shall obtain the volume of fluid raised above the
level in a space included between any number of vertical
planes of different materials.
Attraction on It follows from the preceding theorem, that the volume
the outside of. 7 of the fluid raised by capillary attraction exteriorly to a
smaller, we shall have, V=
a prism.
prism immersed in a fluid at its inferior extremity, is equak
Qe-—e . :
to ap ae c=jlqxc; c being the outer circumference
oe
5 :
Hence increase Of the prism. The increase of weight of the prism, owing
of weight, to capillary attraction, is equal to the weight of this volume
er diminution, of fluid. It changes to diminution, if q¢ be negative, and
then the prism is raised by capillary action. If the base of
the prism be a very narrow rectangle, of which ais the —
longer side, and 7 the shorter, putting z for its height, its
solidity will be adé/, and its circumference, c, will be
2a+27; and the volume V of fluid depressed by capillary
action will be ag/x (1+—). Putting & then for the
ratio
e for the force of attraction which that of the greater has ”
ee Std
ON CAPILLARY ACTION: » 295.
ratio of the specific gravity of the prism. to, that .of ‘the.
fluid, the weight of the prism will be to that of the volume
; l
ee | fluid depressed asik: qx ( i¢—). By suitably di- or equilibrium,
minishing ¢ therefore, we may render the two weights equal,
and thus keep the prism at the surface of the fluid. From
‘the preceding principles too we may determine the diminu-
tion of weight of a body completely immersed in a vessel
filled with several fluids.
If the end of a very slender tube be immersed perpendi-
cularly in a fluid, putting / for the radius of the cavity of
the tube, and q for the height to which the fluid is raised
above the level in it, we shall haye, by my theory of ca-
cos. @
; a D
surface of the interior fluid forms with that part of the
inner surface of the tube, which is in contact with it.
When. the fluid is depressed below the level, this angle
exceeds a right angle, and then its cosine becomes negative,
as well as q: but «is a constant quantity, which depends
only on the weight and action of the fluid on itself. By
2 eadooaac! i
g Drsiog Z
have cos. deta aa i — (1.)
x
5
-°But it has appeared in the theory quoted, that, ¢ being
null, wis equal to two right angles: which may be con-
- eluded likewise from the analysis I shall give in a supple- Resistance a
’ disk opposes to
ment to that theory, on the resistance that a very large separation from
circular disk, applied to the surface of a fluid, opposes to fluid.
its separation from the fluid. From this analysis it follows,
that, @ being the radius of the disk, supposed of the same
matter as the preceding tube, this. resistance is equal to
gDxrxi?x V2xX cos.72
SEATS Saiferio .slucaioe.
be null, when ¢ is null, or when the disk has no action on
the fluid; we shall then have cos. $ null, which gives
@==2¢, and consequently cos. a=—1:; thus the equation
pillary action, J = ; w being the angle which the
: therefore we shall
what precedes we have,
: but itis clear, that it must
; D
(1) will give e’= ts ae and consequently = cos.* X im.
Hence
“Rd EX
996 ; ON CAPILLARY ACTION.
Hence the preceding expression of the resistance the disk
opposes to its separation from the fluid, or, which comes
to the same thing, of the weight necessary to raise it, be-
Attraction of a comes 2 Txi* x J/eDxe. ‘¢ For disks of the same dia~-
che opie meter therefore, and different substances, the squares of
ble from its these weights, divided by the specific gravities of the fluids,
pong bac are proportional to the value of ¢.”? Accordingly, by very
accurate experiments on the resistances opposed by disks
to their separation from the surfaces of fluids, we may de-
termine their respective attractions for those fluids.
Two important observations are here to be made: the
first is, that e expresses the action of a plane of a sensible
thickness on a fluid plane of a sensible thickness parallel
to it, and touching it by the right line, that terminates
one of its extremities; whatever be the laws of the at.
traction of the molecules of the fluid for those of the
plane, and for each other, even in the case where these
jaws are not expressed by the same function of the distance.
But if this function be the same, then the values of e and ¢’
are proportional to the respective intensities of the attrac-
tions; or, which comes to the same thing, to the constant
coefficients, which multiply the common function of the
distance, by which the law of these attractions is repre-
sented; but these values are relative to equal volumes.
To show this, let us conceive two capillary tubes of the
same diameter and different substances, but in which a fluid
rises to the same height. It is clear, that, if in these tubes
we take two equal volumes, infinitely small, and similarly
placed, with respect to the interior fluid, their action on
this fluid will be the same, and one may be substituted for
the other. But to have their attractions in equality with
the masses, the attractions of equal volumes must be
divided by the specific gravities: the values of ¢ and ¢’ there-
fore must be divided by the respective densities of the dif.
ferent substances.
The second observation is, that the preceding results
suppose e less than e’: for, if e exceeded ¢’, the fluid would
unite intimately with the disk with which it was in contact,
and thus form a new disk, the surface of which in contact
with the fluid would be the fluid itself.. But as by the pre~
ceding formula we may determine the resistance, that such
a disk ‘
GXIDATION OF LEAD. 297%
@ disk would oBppse to.its separation; we may be certains
that ¢ is less than ¢ e’, if the resistance opposed by a disk
be less than the resistance thus calculated.
a
XIV.
Fe from Mr. Devavitiz, M. D. of Cherbourg, to Mr.
Vauquelin, Member of the Institute, on the Oxidation
of Metals, and particularly on that of Lead*.
SIR,
Luave undertaken, and pursued as far as my occupa- Experimentson
pations would allow me, some experiments on the oxida- Sag of
fion of metals, particularly on that of lead; and thongh the
results I have obtained are such as to inspire me with a wish
to push my inquiry still farther, as the publication of these
results, which I conceive to be not yet known, at least to
many, may throw some light on the theory of oxidation in
general, and contribute to render more economical the oxi-
dation of lead in particular, as well as the preparation of
some salts, that have this metal for their base, I shall do
myself the honour of sending you a short account of these
results, and of the means I adopted to obtain them. If
dike me you think them new, at least in some respects, I
beg you would give them that sort of publicity, that may 2
t appear to you most suitable.
It is “known, that, in cleaning bottles, when a Bei Shotoxided ia
“quantity of shot is shaken in water, the friction in a short Washing bottles.
_ time separates particles of lead, which, being suspended in
the water, render it turbid, and give it a slate gray colour.
If the agitation be carried farther, thé particles suspended .
in the water become of a lighter gray ; and by continuing
‘it they grow whitish, and at length of a pretty fine -
white.
- This oxide of lead has such a tendency to unite with The oxide pow-
carbonic acid, that on being exposed to the air, when erfully attracts
taken out of i air, it is covered almost immediately with aaa
}
* Annales de Chimie, Vol. LXVIII. p. 92.
‘
Vou. XVII. “Aveust, 1807. x a pellicle
298
May be kept
sinder water
uachanged, |
\
OXIDATION OF LEAD.
a.pellicle of a brilliant white, which appears to be nothing
but. carbonate of lead.
If kept under water, this oxide of lead undergoes no
perceptible change, whether it be exposed to the light, or
defended from it. But if it be kept ever so little time ina
but exposed to flint glass phial with a little water only, it is found to attach
air and light
becomes yel-
Jow, and then
red.
Changed to
massicot and
minium by
heat.
Easily and
cheaply manu-
factured.
Method of
making it.
itself to the sides of the phial above the surface of the
water; and if the phial be exposed to the rays of the sun, that
portion of oxide acted upon by the light changes, successively
from white to yellow, and from yellow to red, thus furnish-
ing massicot and minium. )
If the white oxide be placed over a fire in a glass capsule
_it changes in a short time, from white to yellow, and from
soe to red, like that exposed to light.
This oxide may be manufactured i im quantity, and at little
expense, so as to lessen the cost. of certain preparations. in
which it may be employed. It may likew ise;be used as it is
in painting.
The following is the method I ae employed to. obtain
this oxide. In a leaden barrel I enclose a certain quantity of
- small shot, with as much water as equals about one fifth of
its capacity, leaving the rest full. of air. This barrel is’
turned round by means of an axis fastened to each. end.
It is obvious, thatit might easily be kept in continual motion
by astream of water.
To renew the air in the barrel, I introduce leaden
tubes at various parts of its segerass ence, soldered to the
sides so that no water can escape, and reaching internally
to the axis of the barrel, while the extremities are a few
inches above its surface*,
* This must mail an unnecessary addition to the weight of the
machine, and cost of materials, at the same time that they must .
be liable to injury. They would admit the outer air equally well,
if the exteynal, aperture were. level: with the surface of the
barrel. T,
if
INSTINCT OF ANIMALS. fa tis at 299
IX. Se” Th Sse tn
An Essay on Instinct, read to the French National Insti-
tute, by Mr. Dupont ve Nemovrs *.
‘Tuoucn Descartes would have brutes to be mere ma- Animals pos-
sessed of con-
chines, itis now the general opinion, that they are conscious
sciousness, and
of ‘their sensations, and that their actions are determined by act upon it.
feelings of pleasure and pain; that they have a good me-
mory; that from repeated experience they form general
notions, founded on a sentiment of analogy; that they are
guided by the pleasure or pain, which they are thus enabled
to foresee, and this frequently in spite of the actual impulse
ef present pleasure or pain; and finally that these means,
‘well managed, may be employed by man to educate them, ™
and lead them sometimes to acquire a habit of executing
with wonderful precision very difficult actions, and even g
some to which their structure seems not adapted.
Neither does any philosopher doubt, that animals have Are capable of
various modes of expressing their wants and passions; and ©*Pressing their
wants and pas-
that those of a superior order, or which approach us im sions,
their organization, learn the signification of several of our
words, which they obey without mistake.
But independent of these faculties, which resemble ours Supposed like-
except in degree, and in which the different classes of ani- mee tshiceee 5
mals differ from each other as much as some. of them from ties.
ais, naturalists have imagined they discern in certain species
other faculties, which appear to them essentially different,
and to which they have given the name of instinct.
These are certain actions necessary to the preservation of Some of ae
the species, but frequently altogether foreign to the apparent ,. oe ae
wants of the individuals, and often very complex; which reason,
we. cannot attribute to reason, without granting them a de.
gree of foresight and of knowledge, that every one would
hesitate to admit. Neither can they be attributed to imi- or imitation.
tation; since it appears impossible, that the individuals by
which tee are practised, can have thus learned them, and
yet those of the same species constantly practice them nearly
3p thesame manner. And it is no less remarkable, that the These iost r¢-
*# Magazin Encyclopedique, February, 1807, ps 437. '
. mg actions
300 ‘ INSTINCT OF ANIMALS.
markable in actions which bear no relation to the degree of ordinary
Secret uae understanding are more singular, more intelligent, and
rently least in- 5 ? : 9
telligent. more disinterested, in proportion as the animals that execute
them belong to classes of a lower-order, and in every thing
. else more stupid. It is among the insects, mollusca, and
Balance of rea- worms, that we observe the most admirable instincts. It |
son and instinct. Le Abe ; 7 Y
seems as if instinct and reason were two faculties made to
compensate and supply.the want of each other; as on other
occasions fecundity compensates the want of strength or
long life. Itis even by a due balance of reason, instinct,
and physical qualities, as acuteness of the senses or bodily
strength, that the species are continued. |
These actions Naturalists have imagined therefore, that animals endued
ascribed to an Pirie) vie : ; a sabe ay ae
internalim. With instinct perform their peculiar actions by virtue of an
pulse. internal impulse, independent of experience, foresight,
education, and all exterior agents; in other words, that it
is their organization, which of itself determines them to act
thus. This conclusion has been adopted by almost all ob-
servers : and if they have differed, it is only in explaining
the manner, in which the organization can impart this de-
termination. The following is one of these hypotheses.
Lypothesis. The want or desire of a certain action can be occasioned —
only by sensattons, or remembrances of. sensations; in a
word by images. IJtis not necessary, however, that a sen-
sation should arise from without, for every external sensa-
tion requires interior movements of the brain and nerves,
without which it would not have taken place: but these in-
terior movements may originate in the organs themselves,
without any external action, as is frequently the case in re-
verie, and in various diseases; nothing therefore prevents
certain animals from being so organized, that internal move-
ments shall regularly arise in them capable of producing |
certain ‘sensations or images, and that these images shall
imperiously determine their will to certain actions.
This does not This hypothesis appears to have nothing in common with
re chen that of innate ideas, the object of which is only gencral or
ideas, - abstract ideas: for they, who justly deny, that the gencral
ideas of man are innate, have never pretended to assert, that
man cannot have sensations from interior movements of his.
own organs, and without the intervention of external bo- —
dies; an assextion, that daily experience would have refuted.
Neither —
_ pont has to encounter is-in explaining, how insects have
_ learned those wonderful precautions, with which they pro- theiryoung.
vide a shelter and proper nourishment for the egg, which
they and sometimes even ethers are about to lay, and the
INSTINCT OF ANIMALS. - 301
~ Neither has it any thing in common with materialism ; for, materialism,
whatever idea we entertain of the intimate nature of the
sentient principle, we are obliged to confess, that it expe-
riences sensations only through the medium of the brain and
nerves.
Finally, neither is it more closely allied than any other or fatalism.
to fatalism: for, every action being determined, either by
a present sensation, or by the recollection of a past sen-
sation, or by the hope or fear of a future sensation, whe-
ther these sensations be external or internal docs not alter -
the state of the question.
Mr. Dupont however appears to have been induced, to Mr. Dupont re-
reject every sort of instinct indiscriminately, chiefly by theJ®cts instinct.
fear of splitting against one of these rocks.
He begins by showing, that the actions of animals of the His system,
higher orders, as quadrupeds and birds, result from a com-
bination of experience with their corporal faculties. In this
there is no dificulty, as it is a point on which all naturalists
are agreed.. He then endeavours to explain physically how
these animals, and children themselves, learn to suck. He
shows, that several species are capable of uttering sounds
sufficiently numerous to form a very complicated language ;
and he asserts, that he has observed them employ some of
these sounds under circumstances so similar, as to leave
- scarcely any doubt of their attaching to them a fixed signi-
fication. His observations on this head are very interesting.
He likewise endeavours to prove, that various species are Animals capa-
capable of improving their operations under certain circum. >! see sa a a
en
Stances: though perhaps the naturalist will object to him,
that he has sometimes taken different species for the same
species improved. Thus the architect beaver of Canada is
not precisely the same as the burrowing beaver of the Rhine;
- and the social spider of Paraguay is not the same with our
solitary spiders.
It may be supposed, that the greatest difficulty Mr. Du- Difficulty in the
case of insects
providing for
_ maggot, that is to be produced from it; though frequently
these
$02 ; , INSTINCT OF ANIMALS.
these insects have never seen, and never will see again, tlid
"egg, or a similar maggot; and the wants of the maggot have.
not the least resemblance to those of the insect that labours
“for it.
Curious in- a ha F
pr cies orike . Among thousands of instances, that might be adduced,
sphex, Mr. Dupont has chosen but one, that of the sphex, or ich-
neumon wasp. In this he cannot be accused of having taken
an easy example. The following is its economy. During
its existence as a perfect insect, it lives entirely on flowers,
When it is ready to lay, itforms a cylindrical hole in clayey
sand, and deposits an egg at the bottom of it. It then
seeks on cabbages a small green caterpillar, on which it
never preyed before; pierces it with its sting, so as. to
weaken it to such adegree, that it may be unable to resisé
the maggot, whichis afterward to issue from the egg and feed
upon it, yet not so as to kill it, that it may not putrefy ;
rolls it up in a circle ; and lays it in the hole upon the egg.
It successively proceeds in quest of eleven more of these,
which it treats in a similar manner. It then closes the hole,
and dies. The little maggot is hatched, devours the twelve ..
caterpillars in succession, and changes to a chrysalis in the
hole. As soon as its final metamorphosis is completed, it
issues from its subterranean abode a winged insect, to enjoy.
itself among the flowers, till it is ready to lay, when it re-
peats the operations its mother had performed before it,
and with caterpillars of exactly the same kind.
How explained. Mr. Dupont supposes in his explanation, that the perfect
by thaauthor. insect retains the remembrance of the sensations it expe-
rienced in the state of a maggot, though its form and organs. ©
are totally changed. He must likewise suppose, though he
does not expressly say it, that the sphex can afterward dis~
tinguish by the sight* the caterpillar, and the sand, of which
it acquired a knowledge only by feeling, and this by its an-
cient fecling of a maggot; for the maggot is blind, it lives
under ground, and when it there becomes-a winged insect
- the caterpillars are devoured, Lastly, Mr.'Dupont dares’ ‘
* This is not necessary: it may distinguish them by the smell, or
in some other way; for it by no means: follows, that, because man
has only five senses, an insect hasno more. W, N.
p TY not
ON SULPHUROUS ACID. 308
hot admit, ‘that the sphex foresees the egg it lays will pro-
duce a maggot, and will have need of all it provides for it:
according to him it does this merely for atmusement, in imi.
tating what it perceived in its infancy.
Ye
Observations on the Sulphurous Acid; by Mr. Puancue.
Read to the Society of Pharmacy, November the 15th,
1806 *. .
Mae. BERTHOLLET made known several remarkable Changes pro-
. Sopeee ° -_ duced by sul-
properties of sulphurous acid, in two excellent Memoirs, phurous acid on
read to the Academy of Sciences in 1782 and 1789. In the sirup of violets
year 1796, Messrs. Fourcroy and Vauquelin read a much eet: ts
more extensive memoir on the same subject at the Institute,
in which they gave a more complete history of this acid,
and of its different combinations.
‘T have considered with great attention the labours of
these learned chemists, but among their numerous experi-
ments I do not find any, which actually relate to the object
of my present investigation; the changes that liquid or ga-
seous sulphurous acid occasions in sirup of violets reddened
» by different acids, and the contrary. This property of the
sulphurous acid I am more eager to make known, as it
may furnish matter for interesting reflections on the theory
of acids in general. : pet
The sulphurous acid I employed in my experiments was The aeid pre-
prepared by decomposing very pure sulphuric acid by means ro eid and
of mercury equally pure. In its preparation I followed mercury.
the process of Berthollet. My sirup of violets was of a
very fine blue, without any mixture.
» Haperiment 1. Sirup of violets, diluted with eight parts Restored the
of distilled water, and coloured red by nitric, muriatic, noe ea
sulphuric, phosphoric, or acetic acid, resumed its blue red.
_ colour on the addition of liquid sulphurous acid. The
colour was not quite so intense indeed, as before it was
¢hanged red, but it had no mixture of the latter colour.
7
_ Annales de Chimie, Val. LX. p. 254. December, 1806.
Exp..
304 ON sULPHUROUS Actt.
Reddened, again of ip. .2. The acids above mentioned, added by: little amd
ag other ‘Tithe to the blue liquor, restored its former red colour im-
“mediately ; the acetic acid- excepted, the action of which
was slower by a few minutes, and it required to be added
‘in‘a pretty considerable quantity.
Exp. 3. Sirup.of violets diluted with a similar quantity
of water, and coloured red by oxalic, citric, tartarous, and
acetous acids, had its blue- colour equally restored by
adding a few drops of liquid sulphurous acidy but on tke
subsequent addition of these acids they exhibited some
peculiar properties, which I shall proceed to mention.
Oxalic acid, 1. The oxalic acid in a small dose produces at first no
chatige. It must be added in considerable quantity, to
make tho liquor assume a violet hue; and several hours
. elapse, before it resumes its red colour.
Tartarons, 2. The tartarous, citric, and acetic acids, mixed in any
citric, and ace- . A y geht - ,
dis: proportion with the blue liquor, cannot again make it red,
even though it remain exposed to the air for twelve hours.
“The sulphurous 3. In these three experiments the blue colour continues
pees i ripe to decrease; whliich indicates, that the sulphurous acid stilt
INS. € .
colour. ‘enjoys its property of destroying colours, notwithstanding
“the excess of the other acids. All these experiments were
‘made in glass vessels open to the air: but it was necessary
to ascertain, whether this agent had any influence on the
_ colour. of the different mixtures; for which purpose I re-
peated the same experiments in boftles closely stopped, and
operating as quickly as possible.
| Experiments made in stopped Bottles.
Exclusion ofait_ Exp. 4. Into nine flint glass bottles with stopples I put
‘did not prevent sinny of violets diluted with water as above, and reddened
the action of the . ; \ s
sulphurous acid, by the same acids, and ticketed them. Into cach’ phial I
dropped liquid sulphurous acid, till the blue colour was re-
stored, taking care to shake the mixture well after each drop, | ¥
and observe the change inducediin its colour. ‘This Hdid with
all the nine phials in succession ; and, stopping them as E
did’ it, I left them at rést for six hours. In this space of
time I observed the biue had lost a little of its pring.
without being affected with any tinge of red. 1 pal
but modified raat 5, _Thad next to examine, whether the acids em-- ‘
the subsequent by
¥ : ployed
ON SULPHUROUS ACID. 305
ployed in the preceding experiments had equally the pro. action of the
perty here of reddening the sirup of violets, that had been wae
rendered blue by the sulphurous acid, and the following
were the results.
_With. the nitric, muriatic, sulphuric, and phosphoric
acids, the blue liquor changed to a vinous red:
With the acetic, to a light violet:
With the oxalic, to a pale rose colour:
With the tartarous, citric, and acetous, mixed in a very
large proportion, there was no tint of red, but a remark.
able diminution of the intensity of the blue.
Experiments with Sulphurous Acid Gas.
Exp. 6. Itis well known, that the sulphurous acid in Experiments.
the state of gas acts with much more energy than in_ the With the gas.
liquid state. Accordingly I was desirous of examining its
action on sirup of violets, diluted as before, and changed
red hy the same acids. I disposed my apparatus exactly in
the same manner as for preparing sulphurous acid. As
‘ soon as the second phial, three parts. filled with distilled
water, was saturated, I opened a communication between
it and a third, filled with a mixture of water and sirup of
violets reddened by sulphuric acid. A few bubbles of the
‘sulphurous acid gas were sufficient to restore the blue colour
of the liquor. To this I substituted asother phial, filled
with a similar mixture, except that it had been reddened by
a different acid: and thus I continued, till mixtures red-
dened by all the acids mentioned in the first experiment had
been subjected to the action of the gas. J did not observe It did not ap-
any very sensible difference between them ; but it appeared on esol
‘to me, that the colour was less weakened by the sulphurous
acid gas, than by the liquid sulphurous acid.
. The slight difference, however, may have depended on
the greater quantity of coloured liquor in the latter ex-
_ periments, and the facility with which the effects of the
' gas could be observed, and its action governed.
These experiments repeated with sulphurous acid obtain. The eat
ed by the medium of charcoal, or that of sugar, afforded one ey ;
similar results. acted the same:
SCIENTIFIC
306 ‘SCIENTIFIC NEWS:
| SCIENTIFIC: NEWS.
Trench National case.
Piss auctions! Tue following prize questions are proposed for the year
Phosphorescent 1809. <A considerable number of substances, under differ.
Substances. = ent circumstances, diffuse a phosphorescent light, more or
less vivid, and more or less durable. Such are the fluate of
lime, and some varieties of phosphate of lime, when thrown
in powder on a heated body; the Bolognian phosphorus,
_when, after having been exposed to light, it is carried into
a dark place; certain suJphurets of zinc, when rubbed with
va hard substance, or even with a quill; rotten wood, cer-
tain fishes, and other animal substances approaching to pu-
trefaction, when in the dark; &c. The Class of Mathe-
matical and Physical Sciences therefore proposes as the sub.
ject of ‘the physical prize, which it will adjudge in the pub-
lic meeting of the first epee in January, 1809, the fol.
lowing question.
‘¢'To ascertain by experiment what relations subsist be-
tween the different modes of phosphorescence, and to what
cause every kind of itis owing, excluding from the exami-
nation the phenomena of this class that are observed in liv-
ing animals.” ,
The prize will be a gold medal of the value of 3000 fr-
(125/.); and the papers must be delivered at the secretary’s
office before the Ist of October, 1808.
The term of the following question is prolonged from the
21st of March to the Ist of October, 1807, in conse-
quence of the change made in the period of the annual
meetings, which will prevent a decision on the papers from
bigs Fe place before January.
Hibernation of | °° 10 determine by anatomical and chemical observations
animals, and experiments, what are the phenomena of the torpidity,
that ‘certain animals, such as marmots, dormice, &c., ex-
perience during winter, with respect to the circulation of
the blood, respiration, and irritability; and to investigate ~—
the causes of this sleep, and why it is peculiar to those
animals.’’
Messrs,
SCiZNTI FIC NEWS. 307
Messrs. Bosc, Silvestre, and Palisot de Beauvois have New members
been elected. members of the institute. Mr. de Beauvois, hee ana
‘who succeeds Mr. Adanson, merited his success by his tras
vels in Africa and America, the fruits of which were the
Floras of Owerra and Benin, already published, and that
of the United States, which he is preparing for the press,
as well as by researches concerning the cryptogamia class.
These researches have not only furnished descriptions of
new species and genera, but more particularly a system of
the fecundation of mosses and mushrooms, of which we
shall give a brief outline. .
Amid that dust of the capsules of mosses, which Hedwig Beauvois's sys-
considered as the seed, is 2 kind of nucleus, or little wet We chen as cad
‘more or less swelled, called by botanists the columella. In.mosses,
this nothing has been observed but a parenchyma, more-or
less cellular; and so itis represented repeatedly by Hedwig.
In this Mr. de Beauvois says he has perceived very small
grains, which he believes to be the true seeds ; and the other
dust, that fills the capsule around it, he supposes to be the
pollen. When the capsule is ciliated, the sete by their
\ motion compress the pollen against the seeds, to fecundate
them, at the moment when they are about to escape.
With respect to mushrooms his opinion is similar. The and of mush-
multitude of little grains, or dust, spread over the gills, or '°°™*
other parts of some, and included in others, as the lycoper-
dons, which have been supposed to be seeds, are according
to him the pollen; which in the same manner fecundates the
true seeds, that are containcd within the gills, or part co-
vered with this pollen, just as they burst from these.
In consequence of this opinion, Mr. de Beauvois has New name of
taken the liberty of substituting the term etheogamia, or Enea
_ uncommon fructification, to that of cryptogamia, to which
the class is equally entitled, even on his own hypothesis,
and which is cer tainly more scientific.
“Part of his Prodrome d’ 4 théogamie is published, in n Prodromus of
which he has announced his distribution of the mosses. In eam 5 ESS
this he has some claim to impartiality; for while in forming
his genera he rejects the sexual organs of Hedwig, he takes
no account of the columella, which he considers as the pistil.
Ia — second part, which is about to appear, he has re-
ait duced
308 SCIENTIFIC NEWS.
duced ‘the number of genera of the mushrooms to sixty,
which he distributes.into six orders.
Seeds of thepa- In a subsequent essay he asserts, that he has seen on young
rasitic fungi —_ plants particles appearing to him similar to the seeds of pa-
pass through iy :
‘the epidermis rasitic funguses, that are accustomed to unfold themselves
of plants. jm the substance of the plants, underneath the epidermis :
and hence he concludes, in opposition to Mr. Candolle, that
these grains pass through the epidermis, to lodge themselves
beneath it.
Mushrooms in- He treats more largely on certain mushrooms, that grow
abe, hy by layers from the top downwards, contrary to other vege.
tables. This observation is not new; but his: opinion is;
for he considers each layer as a new mushroom, produced
from the seed of the layer above it.
Theraphiaof | He has likewise shown, that the flowers of the raphia of
Owerra different oe as : C
Fonte eee Owerra differ too widely from those of the sago tree of the
tree. Moluccas, to continue them in the same genus of palms.
ae de Can- An, unsuccessful competitor of Mr. de Beauvois was
olle.
Mr. de Candolie, who, though young, has: distinguished
himself in vegetable physics, as well as in other branches of
Action of artifi botany. Among his labours may be particularly noticed his
cial light on .
plants.
at first imperceptibly, at length effects a total change in the
Production of habits of vegetables: on the cortical pores: on the produc.
Pe. by Ie tion of oxigen gas by green lichens, which has been denied,
The mistletoe but the reality of which he has proved: and on the vegeta.
A ent is but tion of mistletoe, which really attracts the sap of the apple-
tree, but cannot draw up water, in which it is directly im~
mersed; a fact of importance with respect to the cause of
the ascent of the sap in plants.
Parasitic fun- Mr. Candolle presented three memoirs to the class on the
ih occasion. The first was on those parasitic funguses, that
develop themselves beneath the epidermis of plants, and
cause several fatal diseases, as the blight in corn. (See
Journ. vol. X. p. 225.) It has been supposed, that the
seeds of this plant were introduced through the pores of the
Their seeds in- epidermis: but as coloured liquids traverse these pores with
eee ee difficulty, and simple application does not inoculate the
roots, plants with these diseases, he conceives the seeds to be in-
troduced by the roots with the nutritious juices, and circu.
late
~
observations on the action of artificial light, which, operating .
SCIENTIFIC NEWS. 3809
late with them till they arrive at places suitable for their
developement. He comnares them in this respect to intes-
tinal worms, which can subsist only within the bodies of
other animals. From this theory, and the observation, that
each parasitic fungus is capable of being propagated only
in plants of the same family, he deduces rules of which the
farmer may avail himself to avoid the contagion. Eighty- ge 200 spe~
four species of these fungi were already known, and Mr.
Candolle has added more than a hundred to the number.
In a memoir on algz he has shown, that these marine Alga. -
plants have no true roots; that there is no trace of vessels
in their organization; that their whole surface absorbs mois-
ture; and that the greener they are the more oxigen gas is
extricated ‘from them by light He adds, that the litile
grains, hitherto considered as their seeds, are merely cap-
sules, and contain seeds much smaller, enveloped with a
viscous matter, which fixes them where they are to grow.
Another unsuccessful competitor was Mr. du Petit. Du Petit
Thouars, who resided a long time im the isles of France and ate
Bourbon, and visited Madagascar. Ife has began to pub-
lish a Flora of these places, rich in singular plants. His The sago tree
observations on the germination of the cycas, or sago tree, Sater ogi
which some have considered as a palm, others as a fern, and the ferns.
have convinced him, that it ought to constitute a separate
family, equally distinct from both.
Mr. Ventenat has published the 20th number of his Gare
den of Malmaison, but ill health has ebhged him to take
some respite from his labours.
In Mr. de la Billardierc’s 23d number of his Flora of A fruit resem-
New Holland, he describes a tree by the name atherosperma, acts
which he enfehiee as belonging to the family of ranunculi, growing in
that may probably become useful in France. Its nuts have *™"°*
the taste and smell of nutmegs, and it appears capable of
- endnring the climate very well.
Mr. yon Humboldt, and his fellow traveller, Mr. Bon- Von Humboldt.
pland, continue the publication of the plants they observed
-in South America. ‘The genus mejastoma alone furnished
them with so many new species, that they might have filled
a separate work with them, » |
- bi They
310 SCIENTIFIC NEWS.
The condor. They have not Jess enriched the science of zoology. The
condor has never before been so accurately described. | Its
size has been much exaggerated. It scarcely exceeds a metre
(3 feet 3 in.) in height, or three or four in spread of wing.
Its general colour is blackish brown; and round the lower
part of the neck is a collar of white feathers.. The male is
distinguished by a fleshy crest on the top of the head,.and a
white spot in the wing.
Electrical eel of They likewise made some curious observations on the
aren: gymnotus electricus. In the water it is capable of giving
such a shock to a horse, as to stun it, so that it falls down,
and is in danger of being drowned. Mr. von Humboldt,
putting both his feet on one just taken out of the water,
felt an acute pain, that didnot entirely go off the whole.
day. Slighter shocks induce a peculiar trembling, a kind
of twitching of the tendons, different from those of com-
mon electricity. The pain is more like that produced by
galvanizing a wound.
Mr. Tenon has given an important continuation of his
Memoirs on the Dentition of the Horse.
Fossil rontains Mr. Cuvier continues his inquiries concerning the ani. —
of lost animals. mals, that appear to have been destroyed by some revolu-
. tions of the globe. He has described five in the Jast half
Genus masto- year, all of the genus mastodontes: the characters of which
ro pane are to have tusks and a proboscis, and their grinders fur-
nished with conical protuberances arranged in pairs. In the
plaster quarries of Montmartre a skeleton of one of the
_ species described By Mr. Cuvier has lately been dug up
nearly entire.
Beauvois's in~ Mr. de Beauvois has published the third sinothas of his
mieskis insects collected in Africa and America.
’ Mr. Vanquelin has instituted an accurate analysis of the
iron ores of France, their products, the fluxes employed,
and the scoria, with a view to ascertain the causes of the
Yron rendered defective qualities of the iron. These he attributes to re-
Pai saa mains of chrome, phesphorus, and i te He ob-
phosphorus, serves too, that this compound, sublimed in the furnaces,
vile ig bears much resemblance to that of the stones that have fallen
from the atmosphere, except ¢hat.these contain nickel also ;
and
~
¢ SCIENTIFI C. NEWS. 8H
and he conceives it not impossible, that the particles carried
up ‘from our furnaces may contribute in some degree to their
formation.
* Messrs. Descotils and Hassenfratz too have been examin. Sparry iron
ing the sparry iron ores; and the former ascribes the infu. °°
‘sibility of some of them to magnesia, which the latter de.
nies. Mr. Leliévre has described a mineral, that has been A carbonate of
hitherto confounded with the iron spars, which he finds to ei
consist of more than half oxide of manganese, near one them,
_ third carbonic acid, only eight per-cent of iron, and two
and half per cent of lime. He has likewise described a
stone, which he found in the island of Elba. This con-
tains more than half oxide of iron, a little oxide of manz
ganesé, and the rest is silex and lime. Its crystalline nu.
cleus is a prism with a rhombic base, its colour black and
opake, its hardness a little inferior to that of feldtspar, its
Specific gravity 4. Mr. L. has named it yénite, from one of Yenite.
the most memorable events of this century.. [From the
battle of Jena we presume; amode of composing new names,
in which we trust he will be followed. by few of the real
- friends of science. ]
~ Mr. Baraillon having discovered some ancient pewter Ancient pewter,
vessels in digging among the ruins of the Roman town of
Neris, near Montlugon, they were analysed by Mr. Anfrye,
inspeaya general of assays at the mint, and found to ‘con.
ly-five per cent of lead.
To the different modes of freeing alum from iron Mr. Se- Method of free-
guin has added another, founded on its difference of solu. stay alum from
bility when contaminated with iron, and when pure. By
dissolving sixteen parts of common alum in twenty-four of
water, and crystallizing, he obtains fourteen parts of alum
.as pure as the Roman, and two nearly the same with that
of Liege. This process might be adopted in the first in-
stance in manufacturing alum, so as to enhance its value
one third.
It is known, that count Rumford adheres to the old the- Heat a vibratory.
ory of heat being simply a vibratory motion of the particles ™otion.
of bodies. As a strong objection to this has been adduced:
the production of heat by condensation, as if some sub-
3 stance
312
SCIENTIFIC NEWS.
stance were mechanically pressed out of the pores of bodies
thus diminished in bulk. In answer to this he has shown,
Heating water
by steam ap-
plied to soap-
boiling.
Ymprovement
An boilers and
evaporators.
that some cases of condensation are accompanied by the
production of cold. Thussolutions of several salts, being
mixed with pure water, lose at the same time both bulk and
heat. The generation of cold by dissolving salts is a well-
known phenomenon, and has been ascribed to the necessity
of a solid’s absorbing heat when it is converted into a liquid :
but here this explanation will not apply, as the solid is al.
ready dissolved, before it is mixed with the water.
Count Rumford has likewise made a very happy applica.
tion of the process of heating water by steam to the manu-
facturing of soap. He has succeeded in builing soap to a
proper degree by its means in six hours, which in the com-
mon mode requires sixty. He conceives, that this saving
of time is partly owing to the concussions given to the mix-
ture of oil and lie by the heated vapour forced into it, and
there suddenly condensed. :
He has also made a new improvement in ballon: for heat.
ing or evaporating liquids. ‘This consists in adding to their
bottoms. several tubes, which descend into the flame, so as
to be surrounded by it on all sides; thus increasing the sur~
face of the bottom, without adding to its diameter,
CIn our next we shall give an account of the Transactions
of the Mathematical Division of the Class.)
i a
ee RE Gee
. Correction.
The Camera Lucida. described in our Journal, No. 71,
p- 1, is sold not only by Mr. Newman, but also by Messrs.
P. and G. Dorzonp, St. Paul’s Church Yard.
.
wee
yes
ae
Miedo Paes our WAPLILp. q
Comans New
ii,
A
JOURNAL
OF
NATURAL PHILOSOPHY, CHEMISTRY,
AND
THE ARTS.
SUPPLEMENT TO VOL. XVIl.
ae
ARTICLE I.
Pescription of a Machine for triturating and combining Quick«
silver with other Substances, by a CoRRESPONDENT.
SIR, as
Tue difficulty and tediousness of the process of combin- Combination of
ing, pure mercury with mucilaginous or fat substances by 2 on
trituration with a pestle and mortar, so as to bring it to ges tedious.
that state of extreme division, in which alone it can exert
all its efficacy as a medicine, are well known; on account Means of ace
of which some have recommended the use of @ small quan- eae say
tity of flowers of sulphur, or of sulphuretted oil, others
_ that of rancid fat, each of which operates by its chemical
action on the mercury, and so far is at variance with the
; original intention. kn forming mercurial plasters the use Hence mercus
of some such substance as sulphuretted oil, or turpentine, i oagicten
has been found particularly necessary} and owing to this tive.
_ perhaps less benefit has been derived from them, than the |
practitioner has expected. I trust therefore an account of Machine for
a machine, contrived to produce the effect very speedily ‘B¢ PU ros
and with little labour, may not be unacceptable to many of
your readers.
The apparatus consists of a piece of cast iron, A, Plate Description of
{X. Fig. 1. about two feet long and four inches wide, cur- earnest.
_yed so as to form a segment of a circle of four feet radius.
|. Vou, Sasi a Pera
3l4
APPARATUS FOR TRITURATING MERCURY, &e.
Description of Perpendicularly to each side of this segment is fixed an
the apparatus.
additional piece of iron, B, by screws or otherwise; and
another piece at each end, C, D, inclining in the direction
of the radius of the circle; so as to stand above it about
four inches, and forma box or trough. This may be made
to stand on legs, or be fixed securely in any simple framing,
at a height most convenient for the person that works or ~
attends the machine.
A wrought iron pallet, E, is to be fitted accurately into
the box, reaching from one side to the other, allowing it
only sufficient space to work easily backward and forward.
The lower end of the pallet is to be made to fit the bottom
of the box; but its lower edges must be rounded off con-
siderably, so as to rise over the matter in the box, and not
drive it all before it. Its shape is more particularly seen at
Figs, 2 and 3, which are on a somewhat larger scale, Fig. 2
being the front, and Fig 3 the side view of it.
This pallet is to be affixed to the end of a vertical shaft
or rod, F, measuring four feet from the extremity of the
pallet to the pivot, G, on whichit turns. The top of the
rod may be secured by working through a chaff mortice,
which will allow it to move backward and forward, but not
admit any lateral motion.
The piece, HI, in which this mortice is made, is fixed
to a cross piece between the uprights, K, L, Fig. 5; one
of which only, KK, is seenin this view: and as this crosse
piece moves on a pivot at each end, though it is prevented
from moving horizontally, it is confined vertically only by
a weight at the extremity ; which weight may be greater or ,
less, according to the degree of pressure or friction re-
quired. Instead of the weight, a wooden or other spring ~
might be made to act on the head of the shaft at G; but in
general a weight will be found preferable. .
The pallet is set in motion by means of a rod M; one
extremity of which is attached to the vertical shaft at F,
where it works on a pin; the other by coupling brasses to
the crank, N, in the axis of a fly wheel, O. A perpen-
dicular view of these parts, with the same letters of refe~
rence, is given at Fig.5. The place where the rod, M, is
attached to the vertical shaft, F, must be so proportioned
to
APPARATUS FOR TRITURATING MERCURY, &c. . BTS
to the throw of the crank, that at every revolution of a
wheel the pallet shall move backward and forward through
the whole extent of the box; to which a cover may-be
fitted, with a longitudinal aperture sufficient for the shaft,
as shown at Fig. 4,
The mercury, and the composition with which it is in- Mode in which
tended to be mixed, being placed in the box or trough, half °°
on one side of the pallet standing in the middle, and half on
the other, the fly wheel is to be turned by its handle, P,
as in common operations. As long as the mercury remains
ain a fluid state, by its gravity it will follow the pallet to the
centre of the box; and assome portion will mix with the
composition at every turn, the whole will soon be com-
pletely blended together.
This apparatus is particularly adapted for combiaing Particularly:
mercury with a composition of sufficient tenacity to form are iS
a plaster, which cannot be done directly in the common
way; so that itis necessary first to subdue the quicksilver
with tarpentine, or sulphuretted oil, and then to mix it
with a plaster previously melted. But with this apparatus
the plaster is softened by the heat generated by the friction,
and the power is sufficient to mix the mercury with it directly;
and this both intimately and speedily.
It is almost superfluous to say, that the apparatus need Applicable to
-by no means be confined to the dimensions here given; and Baise ies
by enlarging them it may be adapted to various useful pur-
_ poses, which will readily suggest themselves to you. Where
this is done, however, it might be found necessary to steady
the horizontal piece, H, 1, by allowing its extremity H to .
work between two uprights.
. Tam,
SIR,
Your obedient humble Servant,
W. X.
Juiy 20, 1807. .
Y2 A Memoir
316 NEW CLASSES OF GALVANIC CONDUCTORS,
Ii.
A Memoir on Two new Classes of Galvanic Conductors;
by Mr. Erman.
(Concluded from p. 249.)
Secr. Il. Of Conductors, that, in establishing a Contact
between the Two Poles, insulate the positive Effect,
while they continue to propagate the negative Electricity
Bobstances that J HAVE placed in a fifth class those substances, which,
tors toeither applied to either pole separately, act as excellent conduc.
STREP tors, but which, interposed between both poles, insulate
negative, when the positive effect, without discontinuing to be perfect cons
they are in con- ductors of the negative. A wish to realise all the combi-
jyunctron. . * ° . aie : :
: nations possible in closing the galvanic circle, excited me to
examine a great number of substances, in order to find
some one that should come under this description. My at-
tempts were long in vain, because the analogies that guided
Flame of phos- my research were very imperfect; and I did not discover
“ai santa property in question in the flame of phosphorus, before
‘ I had found it unquestionably, to exist in a solid body. This
body is alkaline soap of every kind, provided it be in the
highest state of dryness possible: at least I have found no
perceptible difference in the electric effects; whether it were
composed of vegetable oil or animal fat, converted into
soap by pure soda, or soda mixed with potash, and pre-
pared for pharmaceutical purposes, or the uses of the arts
and domestic economy. Ali these soaps exhibited the ef-
fects I am about to describe, provided the essential condi-
tion of their being desiccated as much as possible weré
fulfilled.
Hard soap, per- A prism of hard soap, completely dried, and applied to
ea ter either of the poles of a galvanic pile, conducts all the
pole, is a con- electricity of that pole into the ground, and produces a
suis maximum of electric intensity at the opposite pole. In this
respect there is no difference between the two poles, and the
soap acts as the most perfect conductor would do. Of this
I convinced myself by measuring with Volta’s electrometer
the divergence produced at each of the poles by the contact
of
NEW €LAS8E8 OF GALVANIC CONDUCTORS. 317
ef metal, a wet finger, soap wetted at the point of contact,
and soap perfectly dry; and I found them all equal in
degree. It will soon appear why, notwithstanding this,
no shock is obtained on employing a prism of soap, unless
it be wetted at the point of contact.
If now two wires, issuing from the two poles of the Ifa wire from
pile, have their extremities fixed in a perfectly insulated eS shen
prism of soap, into which they should penetrate a few lines, an insulated
no remarkable effect is perceived : that is to say, after having pasos 4
brought the two poles to the same intensity, by applying to not be com-
them an insulated metallic rod, the electrometers of the ?!*t*¢.
two poles will act as they did before the intervention of
the soap, and when a stratum of air insulated them per-
fectly with respect to each other. But the instant a free If this soap be
communication is established between the soap and the Pei FO
ground, the positive electrometer exhibits a maximum Of electricity will
divergence, and that of the negative side loses all signs of it, Peet
precisely as if a communication had been established be. positive.
tween the ground and the negative pole itself. Consequently
the soap, which insulates the positive effect, is a perfect
conductor for the negative; to which it belongs throughout
its whole extent, for if you touch the soap with a fine point
ever so near the place into which the positive wire is in-
serted, itis impossible to take from it any portion of elec-
tricity, so perfect is the insulation of this pole.
A very striking proof of this paradoxical property is, Touching the
if one finger be applied to the wire of the positive pole, Ly aie ia
and another finger wetted to the soap, no shock is felt, finger and the
and the electrometers do not show the least change in their ae wasieget
j E ¥ z oes not forma
respective divergencies. But if the experiment be repeated communica-
by establishing a communication between the positive pole tion:
: . f both fi
and the soap with both fingers wetted, a very perceptible a ie: ie
shock will be felt, and the two electrometers will arrive at is felt.
an equal and a very weak degree of intensity.
These facts are sufficient to establish the existence of this
fifth class of substances; but on pursuing our researches
farther we meet with many interesting phenomena.
To discern these the better, the continuity of one of the An apparatys
wires shoulil beinterrupted, and an apparatus for extricating apes ak
gasses be interposed between its parts. In this case no forming part of
hemical] the positive
318 NEW CLASSES OP GALVANIC. CONDUCTORS.
cue is notaf- chemical effect will be perceived, the insulation of the,
even ifa wet Positive wire being an insurmountable obstacle to it. If
eee ae in now a little sponge, or a piece of cloth, be wetted with.
the soap and Water, and placed in contact both with the negative wire
negative wire. and the soap, every thing will remain as before, ‘and there
ye will be no trace of chemical decomposition. But the mo-
the least wet Ment.this wet conductor is. so placed, as to touch at the
ae past same time the positive wire and the soap, gas will be ex-
tive wire. tricated in torrents, and the electrometers will indicate the -
completion of the galvanic circle. Thus the smallest quan.
tity of water is sufficient, to destroy at once the anomaly.
of insulation, which characterizes this substance, and.con-
vert it wholly into an excellent conductor, I. have fre-,
quently seen this effect result, from the simple application,
A coin damped of a piece of.money, which I had damped on one side,
enone side. merely by breathing on it, and which I afterward placed
on the surface of the soap, and in contact with the positive
wire; while the same piece of metal, in.the very same.
position, produced no effect in its usual state of dryness.
No fluid but I know no fact, where the indispensable necessity of
pee arg water in a galvanic action declares itself in a more astonish.
‘ ing way: for the property of converting the whole mass ef;
soap into a perfect conductor for the two poles in com.
munication, by the contact of the positive wire, belongs.
exclusively to water, and is not, as might perhaps be sup-
posed, 4 property of fiuidity in general. Mercury, naph-
tha, oils of every kind, and other liquors not.aqueous,;
poured into a hollow made in the soap at the spot where.
the positive wire is inserted, produce noi the least effect.
anditis decom- Jt is very remarkable too, that water thus applied between,
Saat the the positive wire and the soap undergoes the same chemical,
decomposition as in the apparatus for decomposing it,, In.
fact, according to the, nature of the metallic wire, with
which the water or wet conductor is,in contact, either an
oxide will. be produced in abundance, or a, gas, whichis
so that theef- easily discernible by the froth it occasions. Hence/it is,
fect ceases opie Patt ee 4 om Ws
whenallthe that the time during which ihe interposed water produces
water is de- its, effect is always limited, being in the direct ratio of the
eas quantity.employed, and the inverse ratio of the intensity.
of the-pile: but in all. cases both the clectrometrical and
, chemical
NEW CLASSES OF GALVANIC CONDUCTORS. 319
chemical effects, which depend on the presence of water,
continue decreasing, and soon cease entirely, when all the
water at the points of contact is decomposed. From that
moment the soap resumes its characteristic property, and
insulates the positive electricity.
It will be proper to introduce here an observation of If there be any
some importance to the success of experiments of this kind. hl dvtiels
They who would repeat them without being able to procure agaceygstitiealy ik
prisms of soap exposed to the air for some years, OF COM- at first, the soap
. pletely dried by the action of an oven ora stove cautiously: gpting 263 Ber
conducted, might be tempted to accuse me at first.of not,
having seen clearly ; for a communication being established
between the polar wires by soap yet damp, both the elec-
trometers and the apparatus for decomposing water will
begin by indicating a more or less perfect completion of
the galvanic circle. But the part that water acts in these
phenomena perfectly explains this want of success. It is
the portion of free water, interposed in the damp soap
between it and the positive wire, that in this case conceals
the characteristic property, by which this substance belongs
to the fifth class. To evince this nothing moreis necessary, But this effect
ceases by wait-
than to suffer a few moments to elapse: the water foreign ; ing a little, till
to the conditions of the experiment will be- consumed with the water in
contact with
more or less rapidity, according to its abundance and the the wire is de-
energy of the pile; and then the whole of the soap will composed.
insulate the positive electricity, while it will serveas a con-
ductor to the negative. On taking out the positive wire,
that has thus been inserted into damp soap, the point will |
be found oxided, if the metal be of a nature to admit it,
which never takes place in soap perfectly dry. It is scarcely Though the
nécessaty to add, that, if this wire be cleaned, and insert. °0°? igi s
ed into any other part of the damp soap, the same excep- again, if the.
tion to the general rule will again recur, since in this new ‘se Hans
point of contact the conductor will find a fresh portion of va
f ee water. The oxidation of the positive wire in damp The cessation
soap might lead to the supposition, that the insulation of “Phenol
the positive pole is owing to the production of this non- oxidation of the
conducting. coat. But the contrary may be proved by em. pings
ploying platina wires, which exhibit the phenomena in
‘question, as soon as the water interposed by chance or
design
320 NEW CLASSES OF GALYANIC CONDUCTORS.
design is consumed on the positive side by the chemical
action of the pile, without exhibiting the slightest trace of
oxidation. Besides, the wires most easily oxided show no
appearance of oxidation, when they have been employed
to establish a communication between the positive pole and
a prism of soap perfectly dry,
The watermust An experiment of importance on other accounts shows,
bis gt adh that the water must be applied to the precise point where
tive wire, the positive wire touches the soap, in order that the positive
effect may be propagated as well as the negative. Let AB,
Plate IX. Fig. 6. be two prisms of soap perfectly dry.
Into each introduce one of the polar wires of the pile, and
then connect them together by a wire C, forming an arc
from one to the other. The electrometers of, the pile will.
indicate a complete insulation of the positive pole; the con-
tact with water of either of the two prisms, or of the in-
termediary arc C, will constantly discharge the negative
electrometer, and carry the positive to a maximum of di-
vergence. If now a wet:conductor be applied between the
wire of the positive pole, and the prism A, into which it,
is inserted, the clectrometer will indicate, that the prism,
and likewise the whole of the intermediate arc C, belong
to the positive pole; since on touching these parts of the
apparatus the electrometer of the negative pole is made ta:
‘diverge, and the positive side is discharged. But the
prism B belongs wholly to the negative pole, and on
touching it divergences are produced the reverse of those
that occur on touching A. ‘The circle therefore is not
completed: and in fact, if an apparatus for decomposing
water be interposed, no chemical effect takes place; while
on touching the two prisms at the same time a shock is
felt, if the fingers have been wetted, and the pile has a
tertain degree of energy. In all cases the simultaneous
contact of the two prisms excites in a prepared frog very
strong contractions. But all these effects, which depend
on the insulation of the positive pole, cease, and instead of
them gas is produced in the interposed apparatus, the mo. _
ment a second wet conductor is applied to the point where —
the intermediate arc C touches the prism B, because it is
at this point, that the arc C exhibits the positive effect.
le
NEW CLASSES OF GALVANIC CONDUCTORS. 32}
It is decidedly shown therefore by experiment, that the pe ucly
humidity of the whole mass of soap goes for nothing in parte of Shes
these effects, and the precise point at which the water should an oe
be interposed is indicated with the greatest precision. ;
I cannot help inviting these, who strictly refer all the Difficulty of
phenomena of the pile to a material and effective circula- Tevet.
tion of the electric fluid, maturely to weigh this experiment non by the cir
without prejudice; for in this way of explaining them the oasis uid.
phenomena of the fifth class can arise only from a greater
difficulty the fluid experiences, when it has to enter into
the mass of soap, while its exit is infinitely more easy. But
how comes it then, that the positive pole is so completely
charged by touching the prism A, before the interposition
of wet conductors? Here certainly the electricity of the
ground must have entered into the prism B through the in-
~ termediate arc with the greatest facility. And why does it
not enter in the same manner into the prism A by the posi-«
tive pole? .
Por my part I have not yet entirely renounced the hy. Water perhaps
Noi : 8 * acts by separat-
pothesis, that the efficacious cooperation of water in the ing into zones
physical and chemical effects of completing the galvanic of opposite
circle is intimately connected with the property it has of “agente
dividing itself then into two zones, one of which exhibits
electrical effects the reverse of the other. -This mechanism
of electric partition, this polarity of water and all humid
conductors, announce themselves in such astriking manner,
when we apply them to the soap, that I can scarcely be-
lieve the physical and chemical effects produced by com. by
pleting the circle through the intervention of humid con.
ductors are not owing to this very mechanism. Whatever
may be the fate of this hypothesis, the developement of
which would lead me too far from my subject, the follows
ing facis appear to me deserving of attention.
The pile and prism of soap being perfectly insulated, let ae be aati 7
the wire of the negative pole be inserted into the SOAP 3 the soap and
and let the other extremity of the prism be connected with the positive
eS pole be made
the positive pole by means of a thoroughly wet hempen by a wet string,
string six or seven inches long. It is obvious, that from
this interposition of a wet conductor between the soap
and the positive pole the galvanic circle must be completed ;
2 as
$22. NEW CLASSES OF GALVANIC CONDUCTORS.
asin fact the electrometers and the apparatus for decom.
posing water show. If now two gold leaf electrometers
be placed in contact with the two extreme portions of the
wet conductor, we shall find, as long as the circle continues
effectively completed, these two electrometers will exhibit
the end of the opposite divergences; for that which is nearest the soap’
sn a will diverge negatively, while that nearest the pile will
hibit negative diverge positively. ‘This may be proved by touching that
ortaa) mare part of the string nearest the soap, by which the electro.
tive. meter contiguous to it will be discharged, and the charge
of the other electrometer will be considerably augmented 3’
but the reverse will take place, if the part of the wet string~
nearest the pile be touched. The partition of electricity’
into two opposite zones therefore is beyond ’a doubt. | e
Ifthe wet string Now let the positive side communicate with the soap by’
ies ete means of a wire, and let the wet conductor be interposed’
andthe nega- between the scap and the negative side, the circle will not
Ee a be completed, and no chemical effect will take place, as has
electricities willalready been observed. But neither will the string exhibit
not take place, ayy partition into. electric zones: for if two electrometers
be applied to the two opposite ends of this string, they will
both diverge in the same direction, and in the same manner ;
and by touching the string in any part both will be deprived
of their divergence. Now to destroy this homogeneousness’
of electrification, and communicate to the string’ the most
tila wetcon- decided polarity, it is sufficient to apply a wet conductor
ductor has been hetween the soap and the wire of the positive pole; for
placed between : 7 i ‘ ‘
ihe sdapand the nroment its interposition has completed the circle, the
the positive two» electrometers at the ends of the string will diverge inj
baa opposite directions; by discharging one the other will ‘be
charged; and this partition of opposite electricities will re-'
main} as long as the apparatus for decomposing water ‘con-
and this effect tinues to indicate, thatthe circle is complete. This com!
willeenies $90 pletion of the circle and partition of the zones will cease
latter conduc- at onee, if the wet conductor applied to the wire of the’
tor is removed. nositive pole be removed. I could wish, that other natural’
philosophers might be struck like me with the singularity’
of ‘this accordance of effects, the importance of which |
think I foresee, if it be farther pursued.
Soap will serve . Among the numerous combinations IL have tried, to as-
as a connecting | 2 certain
NEW, CLASSES, OF, GALVANIC. CONDUCTORS. 323
certain with some precision the particulars of the pheno- medium be-
mena, that are. afforded by soap applied to the galvanic tien EP se
pile, L haye observed nothing, that is not completely ex- for completing
plained by. the definition of conductors of the fifth class. A
Thus a prism of soap applied to the positive and negative
extremities of the two piles, each of which has the same
number of plates but in an inverted order, connects these
piles completely, as long as the object is not to complete
the galvanic circle; and give to their poles the same diver-
gences, asif they were connected by a perfect conductor.
But to obtain the physiological or chemical effects, that without a wet
require the completion of the galvanic circle, a wet con- foe
ductor must be placed between the prism of soap and the pole.
positive pole. If. this interposition were made at the nega-
tive pole, it would have no effect. ‘The reason why I men-
tion this experiment, which is only a corollary from what
has been already said, is to point out a very direct solution
of a. point of theory, on which philosophers diifer, that
may be drawn from it.
it has been asked, what kind of electricity belongs ex- This leads to a
clusively to,each of the two different metals of the pile; and Solution of the
4 : ag ‘ question, whe-
opinious have been, divided on the point. They who as- ther the silver
sert, that the elements of,the galvanic pile are silver, a the zinc be
; F sa Ryd in the positive
wet conductor, and zinc, ascribe the positive electricity to state.
_the silver. They on the contrary who maintain, that the
proper combination is silver, zinc, and a wet, conductor,
consider the zinc as the metal charged with positive elec-
tricity. I have hesitated some time between the two parties,
for svant, ofa direct unequivocal proof, and. from unwil-
lingness to sacrifice my,scruples to the authority of Volta _
himself. Now it appears, that.the properties of conduc-
tors of the fourth and fifth classes furnish the most direct
and palpable .means.of .deciding the question. Among
several other analogous proofs, the following is*one of the
most evident, and most easy to be.exhibited.
, Between the last pair of plates of zinc and silver in any A piece of dry
pile, place, a slice of perfectly dry soap, then establish eae ee
communication between the two poles by the interposition the last two
of an apparatus for decomposing water, and no. chemical gene son
effect will be. produced. With a camel-hair pencil lightly eq:
moisten
324 NEW CLASSES OF GALYANIC CONDUCTORS.
fies nat next moisten that surface of the soap, which is in contact with
éatted, itis the the silver, and again establish a communication between the |
same: two poles: still it will be the same. But the moment that
if the side next : ; ; a
thezinc be _— the soap is moistened on the side that touches the zinc, the
wetted the pile chemical and physiological effects will exhibit themselves
acts effectually.
The zinc there- fully. Now as we have already found, that a wet conduc-
foreisin the tor is efficacious between the soap and the positive side ex.
Positive state. : ote 3 “ps
: clusively, it is demonstrated beyond controversy, that it is
the zinc, and not the silver, which constitutes the positive
agent in the pile. ;
I know not at present what other substances belong
to our fifth class. It appeared above, that the flame of
phosphorus must decidedly be referred to it. Frequently I
Animal jelly have seen indications of the same property in animal jelly
and ivory have reduced to a certain degree of dryness, as well as in ivory:
i a " but other masses of these substances exhibited these phe-
long to this = nomena in a very equivocal manner, so that I refrain from
fifth class. ae :
deciding upon them, and at present shall only mention soap
and the flame of phosphorus as included in this class.
Many supposed It would be interesting to examine, with a view to this
age ee classification, a great number of substances, which have
mined, been considered as nonconductors, because the galvanic
circuit is not completed by their interposition: but it is
now completely proved, that this test is insufficient; and the
argument in favour of the nonidentity of -galvanism and
electricity, taken from the mode of action of flame, shows
that errours of this kind may prove dangerous to the
theory. :
Why is ice a The field of observation here opened may prove fertile
manga LIE in general results for the chemistry of electricity. By
-eonductor,and what mechanism of action is it, that water, sa far divested
mel NE ee of caloric as to become solid, perfectly insulates the ef-
fects of galvanism, as I have elsewhere shown: that after-
ward impregnated with a certain quantity of caloric in the
liquid state, it transmits these effects with certain modifica-
tions, dividing itself into two zones, one of which is a
conductor of positive, the other of negative electricity :
and that lastly this same water, in passing to the elastic
state by an excess of caloric, returns again to the class of
perfect nonconductors, as may easily be proved, by re-
ceiving
: ~
NEW CLASSES OF GALVANIC CONDUCTORS. 33a
ceiving between the two polar wires of a pile, furnislied
with its electrometer, the current of vapour from an eolipilé
near the orifice, where it has its whole transparency, and
is free from all mixture of vesicular vapour and precipitated
water? When by a well-managed heat tboroughly dried Soap whea
soap is brought to a considerable degree of softness, this oe
substance likewise undergoes a gradual change in its faculty
of conducting the electricity of the pile; and the nearer it
-approaches a state of liquefaction, the more it loses the
property of insulating the positive electricity in completing |
the circle between the two poles, so that ultimately we
perceive evident traces of the decomposition of water in the
interposed apparatus. Other substances lead to chemico-
physical researches not less interesting. Sulphur is a non- Sulphur and its
conductor ; so isits flame. Phosphorus and amber are both ane saan"
nonconductors; but their flames are conductors. Here is Bier Pay
one anomaly. . But how again are we to account for theyet their flames
difference in these two conducting flames? Why, in closing Bi. opposite
the circle between the two poles, does that of phosphorus €lectricities.
insulate the negative effect, and that of amber the positive ?
‘ Itis very probable, that all these varieties. of action are Perhaps the
a intimately connected with the chemical affinities of the two ona a
elements of the electric fluid; and we may flatter ourselves to the chemical
with the hope of some day obtaining results of importance, Aaa
by sedulously varying and analyzing these facts. Lest how-
ever I should be accused of exaggerating the importance of
these phenomena, in deferring their explanation, by way of
ecncluding I will mention some hypotheses, which have for-
merly guided my researches, but which no longer appear
plausible tome, since the facts that have presented them.
selves to me have become more numerous and diversified. I
relate these only to show, that I have sincerel y endeavoured
to lay open the whole subject, so as to reduce it to a simple
$< js-this all ?” om
. Do conducting flames, which in completing the circle in- Hypothesis that
sulate the negative effect, owe this property ta a stratum of & pe soe
oil, which, formed of its elementary principles in the act Seti ie |
of combustion, and deposited on the negative wire, renders
it impermeable to the electric fluid ? Carbon, hidrogen,
and oxigen, exist in fact in most substances, which by their
: _ combustion
826 ' NEW CLASSES OF GALVANIC CONDUCTORS.
combustion exhibit the phenomenon of negative insulation.
It is natural too, that this oil-forming combination should
be produced at.the negative or hidrogenating pole, and not
_at the positive, where, on account of the oxidation that
takes place, water and carbonic acid must rather be form-
ed. Do not the fuliginous ramifications, that expand much
more abundantly from the negative pole, owe thtir existence
to this oleification, which detains them, renders them mote
compact, and feeds them by a continually renewed come
' bustion ; while on the positive side the more perfect oxida-
tion causes them to disappear in gas and vapour, before
they have been able to expand themselves ?
Reasons why This specious hypothesis involves the following difficul- —
this cannot be
the cause, ties. The flame of the purest hidrogen gas insulates the nes
gative effect. Now where shall we find in this the carbon
necessary for the formation of oil? On inspecting a thou-
sand times, even with a microscope, the negative and posi-«
tive wires perfectly cleaned, and kept a long time in the
flame of alcohol, I never could perceive the least difference
between their extremities. Besides, on bringing together
with the greatest possible dexterity the positive and negative
wires in the flame itself, a spark is constantly perceptible.
Farther, both the electrometers and apparatus for decom
posing water show, that, the moment any filaments of the
arborescent soot extend from one wire to the other, the }
galvanic circuit is completed; which would be impossible,
if the negative wire were rendered impermeable to the elec.
tric fluid by any non conducting coating. Lastly, how
can it be supposed, that such an insulating coat should be
formed in a single instant over all the surface of a disk of
‘several inches, held two feet above the flame? ~The cause
of the phenomenon then, which all these facts have placed
before us, is not so superficial, as the hypothesis supposes.
Hypothesis, The following is an analogous hypothesis, which likewise
that acid gene- ‘ . as
rated at the po- | had formed respecting the mode of action of soap in insu-
sitive pole ab- Jating the positive cffects. The positive wire of the pile is
stracts the alka- “Re : *: He De 2 nee
li of thesoap, . the seat of oxigenation, as ‘the negative is of hidrogenation.
and then leaves Jf then the alkali of the soap be neutralized by the contact
a coat of oil. -
‘of the acidifying wire, the oil, or fat, will be set at liberty, —
and thus insulate the positive pole, the conductor of which |
ik
-
mi Aig -
NEW CLASSES OF GALVANIC CONDUCTORS. 327
it surrounds. Indeed I have found, that, in an alcoholic n fact oil is set
solution of soap diluted with water, a manifest separation :
of the oleaginous base of the soap will be effected after some
hours, and it will be deposited on the wire of the positive
pole.
This fact is certain: yet itis easy to show, that the hy- Yet this cannot
be the cause of
pothesis to which it serves as a base is not less manifestly in ,1,, wbetine:
contradiction with several particulars of the phenomena, na.
which it ought to explain. In-reality, when several prisms
of soap, connected together by intermediate arcs, are ex-
posed to the action of the pile, there is no doubt a partial
insulation with respect to each point of insertion that cor-
responds with the positive effect: but we cannot thence ©
conclude, that this insulation is absolute, since the negative
pole may be acted upon through all these prisms, and all
the points of insertion of their conducting arcs, so as
to take from it its charge. At the points of contact of the
positive wires therefore there is no absolute obstacle to the
passage of the electric fluid, and the hypothesis of an insu.
lating coat of oil falls to the ground. Besides, in perfectly
dry soap the positive insulating effect displays itself the in-
stant it is applied, when no preceding chemical decomposi-
tion can have taken place.
‘On this hypothesis too how we shall explain the produc- Farther difficul-
tion of the same effect by the flame of phosphorus? Must @s the way.
we recur to anew hypothesis to account for this single fact,
and say for instance, that here the oxiding action of the
acid i in the state of vapour, being produced with more ener-
gy at the positive wire, renders it impermeable to the elec-
tric fluid? But this hypothesis would be equally untenable,
since platina wires exhibit the phenomena of positive insu-
lation as well as any other metal; and this effect manifests
itself the first moment of contact exactly in the same degree
as after the long-continued action of phosphorus in ignition.
Besides, on this supposition it would be difficult to explain,
why sulphur does not produce the same effect.
I am persuaded therefore, that these hypotheses are Thecause-
completely erroneous; that the cause of the phenomena we Seesaw
have discussed lies deeper, and is purely chemical; and that shown,
we
325 OXIDATIONS OF IRON.
*
we shall not be able to explain it, till these facts have bees
more thoroughly studied, than has yet been in my power.
Classification of Meantime E would propose, for convenience, the follow-
pt aera ing classification and nomenclature. All substances, appli<
tricity. ed to the poles of the pile are either, Class 1, énsulators 3
or they are conductors. ‘The latter are distinguishable into,
Class 2, :perfect conductors; and imperfect conductors.
The imperfect are, Class 3, bipolar imperfect conductor's :
Class 4, positive unipolar: and Class 5, negative unipolar’.
2008
Inquiries concerning the Oxidations of Iron ; by Mr. Darso..
(Concluded from p. 280.)
Farther differ- I DISSOLVED six grains of iron in muriatic acid without
ee heat; and at the same time, in a separate vessel, six grains
bysulphuretted of red oxide, which I saturated with sulphuretted hidrogen.
Bidrogen. Four hours after I precipitated both these solutions by an
alkali, and I found, that the precipitates of the green so-
Intion by sulphuretted hidrogen passed to red with the
greatest rapidity. On pouring off the supernatant fluid,
and letting water fall from some height on the oxide, it
turned red immediately ; but the precipitates of the other-
solution resist this trial. The green oxide by sulphuretted
hidrogen, redissolved in muriatic acid, precipitates red; or
at least it does so after two solutions. The common green
oxides of iron, when recent, retain their colour even after
being redissolved in acids five or six times. The reason of
this no doubt is, that in the common green solutions of
_ iron the hidrogen combines with the iron in the state of nas~
tent gas, or very dense, and forms a more solid combina~
tion, than that into which the hidrogen furnished by sule
| phuretted hidrogen enters with the red oxide.
Thegreenox- — If the green oxides of iron be hidrurets, as I suppose, it ‘
“i higraaeten eg easy to account for the alteration, that the green salts of
is explains
their alteration iron undergo by exposure to the air. It is not to be wons
mtn: dered at, that hidrogen combined with oxide of iron should ~
be volatilised spontaneously at a heat above 10° [544° F.].
Ls ‘ | Almost
.
OXIDATIONS OF IRON. | i 8329
Almost all the combinations into which hidrogen enters are
decomposed in the same manner, particularly when they
are dissolved in water; as sulphuretted, phosphuretted,
and carburetted hidrog 1. All the vegetable acids likewise
are decomposed spontaneously, when they are dissolved in
water: and alcohol diluted in water is the same. The at-
mospheric air has no more influence in these phenomena,
than it has in those of fermentation and putrefaction. Alf
these operations require open vessels, because they evolve
different gasses, which, if they were confined by any pres-
sure whatever, would check the progress of the operation. :
The experiments related in this paper I consider only ‘as These.experi-
the outlines of a more extensive and deeper investigation ; 2\)' Seok
4 : arther inquiry.
but as different circumstances have already obliged me to 1
defer this research for one twelvemonthy and it is very
doubtful how much longer it may be, before I shall beable
to enter upon it, I was desirous of announcing these facts
to the chemical world.
Corollaries dedusible from the preceding Facts.
1, All the oxides of iron soluble in acids are red: andInferences from
though their proportion of oxigen varies from 15 per cent ™
to more than 50, they are not distinguishable from each
other by any means hitherto employed in chemistry.
2. The white oxide of iron is a salt with excess of oxide.
3. The green oxide is not a peculiar oxide, but a hidru-
ret, or a combination of the red oxide with hidrogen.
_ 4, The atmospheric air has no influence on solutions of
iron, at least in the ordinary temperature o the atmos-
phere.
_ 5. The saturation of iron with oxigen in its oxides does
mot destroy its magnetism, as hitherto has been asserted.
_ Every oxide of iron is magnetic, or may become so without
losing an atem of oxigen.
ee
Note, referred to, p. 224. It has long been observed, Magnckion of
that fhe magnetism of iron is weakened or disappears alto- - ee
gether in its oxides. At different periods this phenomenon its oxides.
Vor. XVII.—Suprrrement. V4 has
|
330 OXIDATIONS OF IRON.
Supposed has been differently explained, according to the manner ia
causes of this. which metallic calces were considered. Previous to the
Loss of :phlogis- pneumatic theory, the maguetism. was ascribed to the pre-
ial sence of phlogiston. After the labours of Lavoisier had
@xigenation. shewn, that the formation of metallic calces was owing to
the combination of oxigen with the metal, chemists naturally
inferred, that the oxigen destroyed the niagnetism: and as
on the other hand facts seemed to prove, that magnetism
was annihilated in oxides highly loaded with oxigen, it was
established as a principle, that oxides of iron ata maximum,
or red oxides, were neat magnetic.
Fhis inconsis- § This principle, which does not agree with the fact I
teht with some : : °
Fete ~~~ have just related, embarrassed several philosophers in ex-
Guide ata plaining certain phenomena. The celebrated Baron von
same? Humboldt, who discovered magnetic polarity in a serpen-
tine, could not account for this property in a mineral,
which appeared on analysis to contain only superoxigenated
This denied by oxide, On this occasion Guyton observed, that the term
chan of superoxigenated, employed by the Baron, was inaccue
rate, for these two properties of being magnetic and super. -
oxigenated were incompatible; and that the magnetism of
the Saxon serpentine, and of other minerals which do not
afford green oxide by analysis, should lead us to suppose
Hauy’s modecfintermediate oxidations of iron. Mr. Haiiy, the learned
caine ee natural philosopher, to whom magnetism is indebted for
of magnetism very perspicuous elucidations, has likewise suffered himself
ahs oxide BY 49 be led away by the chemists; and, endeavouring to ace
«ount for the magnetism, which some red oxides of iron ace
quire when strongly heated, says, that ‘* this is owing to
‘S the heat reducing some particles of the oxide, at the same
‘6 time that it assists the magnetic action of the globe, &c.’” —
. At first T subscribed to such respectable authorities, be.
cause, as Bacon observes, ovortet ediscentem credere; and
because, in the eommencement of these researches, I tried
several red oxides, obtained from different solutions of iron,
23 well as several aperitive saffrons of steel, which did not
Miapnetic axi- give me the least sign of magnetism. But as I afterward
ae much perceived, that oxides greatly loaded with oxigen, or such
as contained +50 or :56, retained their magnetism, whila
Boo others
OXIDATIONS OF IRON. $31 .
others that had scarcely -20 * were not attractable, I con- Unmagnetic
cluded, that there was some other cause acting at the same ei hina
time with the oxigen, or perhaps exclusively, to destroy
the magnetism. Reflecting on the circumstances, that pre-
side over the formation of all these different oxides, I sus-
pect, that in these phenomena, as in most of those to which
the oxides of iron give birth, too much has been ascribed
to the influence of oxigen, by referring to it effects in which
it has no concern. Jf the Joss of magnetism in some red The magnetism
oxides of iron be not exclusively owing to astate-ef extreme rien by a
division, this at least has a more decided influence on ay
than the presence of oxigen
When the magnetic nti of which Ihave spoken, is Concentrated
precipitated by concentrated alkalis, and without the solu. tok, nent
tion having becn much dilufed by water, the precipitate is oxides:
amore or less blackish brown, it does not charge by dry-
ing in the open air, and it-is decidedly magnetic. If, on dilute solutions
the contrary, the solution and the alkali be diluted with °°
water, which has been boiled a long time to remove every
suspicion of superoxidation, the precipitate is red, like all
those called oxides at a maximum ; and if it be dried in the
open air, or by a gentle heat, like the preceding, it gives
no signs of magnetism. Now we cannot ascribe this differ-
ence of colour and of magnetism to a different proportion
of oxigen; for if we try the experiment with two cqual
‘parts of oxide, we shall find, that the weight of the red
oxide is the same as that of the magnetic. The difference of
magnetism therefore, like that of colour, depends on the
difference of density, or the greater or less distance bee
‘tween the particles of the two precipitates.
In fact, when the solution is concentrated, the particles This is owing to
of the oxide touch each other, or at least are much nearer pate ne
together, than when the solution is diluted. with -water: i particles,
and this difference of approximation is im the ratio of the Laan he
bulk of the two solutions, since the distribution of the oxide the quantity of
in both cases is uniform. Let us suppose, that the differ. id ns ain
ence of approximation be in the ratio of one to ten; or,
* Those obtained from the green solutions, of which Tr have
spoken in the course of this Paper. See p. 273.
42 which
3352
The case is the
game with ox-
ides by calcina-
tion,
and red oxides
when rendered
snagnetic by
heat.
2
4
OXIDATIONS OF IRON-.
which amounts to the same thing, that the thickness of the
columns of fluid separating the particles is 4 of a line in
the concentrated solution, and a line in that diluted with
water; what will happen, if adrop of alkali fall on any
point of the concentrated solution? The alkali will deter-
mine the precipitation of a certain number of particles of
oxide, which will be at first =", of a line from each other,
as when they were combined with the acid: but their spe-
cific gravity, assisted by the pressure of the atmosphere
and of the solution, will be capable of overcoming the re-
sistance opposed to their approximation by the little column
of liquid that separates them. This is the reason why the
precipitate is blackish, retains its magnetism, and at the
expiration of a few minutes is insoluble in cold muriatic
acid. .
In the solution greatly diluted with water, though the
alkali determines the precipitation of an equal number of
particles, and though their specific gravity and pressure act
in the same manner, as the resistance opposed to them by
the columns of fluid is ten times as great, their approxima.
tion cannot be so complete. Hence the difference of coe
Jour, absence of magnetism, and facility of solution in
acids. i sists
Besides, when extremely fine filings of iron are calcined,
and divided by trituration in the course of the operation,
till they have taken up 15 per cent of oxigen, we obtain a
very fine red powder, much less magnetic than oxides with
30 or 40 per cent, obtained by the common process; that
is te say, with common iron filings not triturated during
the course of the process. .
Finally, the red precipitates of solutions of iron, and
most of the aperitive saffrons, after they have been well
dried, exhibit no signs of magnetism. But if they be ex
posed to a strong fire for some time, their bulk diminishes,
their colour is heightened, and they are decidedly magnetic.
Now we cannot say here, that the magnetism is owing to 2
loss of oxigen, since the experiments of Proust, and more
recently those of Berthollet, have proved that these oxides,
exposed to the strongest heat of our furnaces, do not give
out an atom of oxigen, .’To the same approximation is to
? be
Se eae
OXIDATIONS OF IRON, 333
be ascribed the conversion of red crayons into magnets,
related by Haiiy in his elementary Treatise on Natural Phi-
losophy; and the magnetic polarity, that displays itself in
all the oxides of iron heated before the blowpipe, observed
by Mr. Leliévre.
_ Besides the weakening of magnetism by division, and Ee eee
even the complete suspension of its effects, are consequences y sakened by
of our theory of magnetism, Though I am not acquainted mnute division
spd : r of the substance
with any accurate experiments, which prove, that magne- gequcted from
tism acts in the direct ratio of masses, a number of facts the theory.
attest, that itis subjected to this law*, Every one knows,
that under similar circumstances a magnet eight inches long-
and an inch thick is more powerful than another of half
these dimensions. The two hypotheses, that account for
the magnetism of the earth, rest likewise on this law: for.
it is in consequence of the magnitude of their mass, that
the action of the magnetic nucleus, or of mines of iron,
extends to such prodigious distances. Without supposing
this law, we cannot account for this phenomenon. Thus,
all other circumstances being equal, a grain of iron will
have a hundred times the magnetic power of ;4, ofa grain,
a thousand times that of ~¢55 of a grain, andsoon: and
the imagination can casily conceive a subdivision, by which
the magnetic power of a grain of iron would be so divided,
and its sphere of action so shortened, that the magnetism of
each particle should not only be unable to pervade the
space that separates it from another, but even to exhibit
_ any signs of magnetism, when brought into contact with a
magnet. An example will elucidate this.
Suppose I present the north pole of a needle to a particle Fhisillustrated,
of iron filings. The austral fluid of this particle will place
itself at the extremity nearest the needle, while its boreal fluid
will be expelled. to the opposite extremity. But as there isa
sufficiently appreciable difference between the distanceat which
the north poleof the needle acts on the two fluids of the particle’
of iron, the south energy of this will overcome the north, and’
through this preponderance it will approach the needle,
%* And even though this Jaw should be slightly modified in some
way, the effects of this modification would be of little account: in
the present discussion.
ne Hee Now
. 334 CURVILINEAR SAW.
Now let us continue to subdivide this particle, till thé dis
tance between the two poles of its molecules, brought into.
contact with the needle, shall be so small, that the séats of
the two poles shall be as we may say compounded together :
the difference between the attraction and repulsion will then
become inappreciable, and the molecule will give no signs
of magnetism. |
Restoration of | It may be said, that this developmert of magnetism in
pete hae oxides strongly heated is rather owing to the action of the
the effectof heat weakening the coercive power that opposes the mag.
caloria, netism. But beside that this coercive power is not a fact
so certain as the approximation, that these oxides undergo
whenever they become magnetic, it can account only for
for it takes part of the phenomena, since in oxides by precipitation,
Ley without vhich can be obtained magnetic at pleasure, heat has na
concern.
Whether oxi- For the rest, whatever be the cause of this phenomenon,
gen may weak- it is proved, that oxides saturated with oxigen are magne.
en Magnetism .
is notdetermin- tic, or at Jeast may become so without losing an atom of
=4- oxigen. _I do not however mean to assert, that a given
quantity of iron saturated with oxigen retains the same
magnetic power as it possessed before it was oxigenized :
for on this subject I have made no experiments.
IV.
Description of a Curvilinear Saw, inventedby Joun TRoTrEer,
Esq., of Soho Square, from whom the following Come
munication was received *. ‘
GENTLEMEN,
A eurvilinear
saw very desira- W oir the view of. obviating many difficulties and ex.
ba penses, which have long attended the operations of those
requiring curvilinear sawing in their trade, and of public
bodies connected with thosé trades, through the licentious
_ and refractory conduct of sawyers, it has been represented
to me as a measure extremely desirable, to adopt more ge-
% From the Transactions of the Society of Arts, &c. for 1806, wha
voted their gold medal.to Mr. Trotter for this invention.
Ree nerally
CURVILINEAR SAW. *3335
wérally mechanical powers, could such be discovered as
would preclude much mystery and manual labour.
Considering the subject in a national point of view, as on scveral nati-
° * : : onal aceounts.
connected with our naval yards in the formation of timber ;
with our military departments, in respect to wheels of
every description; with our whale and herring fisheries ;
- our public and private breweries and distilleries; our East
and West India Companies, and other bodies depending on.
cooperages, as well as other minor trades peculiarly liable
to the evils complained of ; I invented a curvilinear saw,
_ which, with little aid of the most ignorant labourer, ane
_ @wers every purpose.
Having effected these ends, suffer me to solicit the honour
.of your acceptance of a model, together with a drawing ef
_ My saw, sufficiently accurate for the use of those in remote
situations to work by, who may wish to usé or make
them,
I have the honour to be,
Gentlemen, :
Your most obedient and most humble Servant,
JOHN TROTTER,
Soho Square, Sept. 12, 1805.
_To the Society for the Encouragement °
of Arts, &c. |
Se ccxe, to the Engraving of Mr. Trotter’ s Curvilinear
Su. Plate X,
¥F ig. 1. Represents a bird’s eye view of the saw and ma- Description of
chinery, The dotted lines show the spindle a, moving on at
two centres 6,6, having at one end a pulley c, and at the
other a concave saw d (witha corresponding convexity to
the curve required to be sawed,) secured on the convex side
bya collar, and on the concave side by a loose collar, and
screw nut.
_ €,e, Two grooved plates, admitting through the top of
‘the bench and fence f, screw bolts fastened by thumb nuts,
by means of which, and a parallel motion g, the fence f is
regulated, and consequently the conductor h of the wood ¢
admits it to be sawed through, as appresented, in the dotted
line at any part required. fone .
Z4 The
336 BOOKBINDER’S CUTTING PRESS.
_ The fence, conductor, and saw, must all be eurved alike
but to saw in smaller circles, with the same saw and at the
same time square at the face of the bench, a steel slider
k, regulated by two screws, is made to press, as o
may require, on the convex side of the saw, and raise ‘the
vertical line of it toa ight angle with the bench; ¢ other.
wise the top of the bench itself must receive the i
tlination to the verhica line o of ms. fixed saw.
the teeth oF the saw are more Beaty showne” ae
Fig. 3. An end view of the same machinery.
Fig. 4. Shows the saw, axle, and pulley, all
iron or steel, and cae i the frame.
reps! il
The press ee | HAVE herewith sent a . oF of an improved press for
ited ee bookbinders, the invention of Mr. James Hardie, book.
>
and saves time. binder, Glasgow. The inventor claims no other merit
than that of having simplified the common press, ren-
dered it more powerful, and adapted it to work more eco=
nomically; or, in other words, to save time to the work.
Generally used man. It has been found so superior to the press m come
iad he mon use, that all the bookbinders in Glasgow and Edin.
; burgh are adopting it. This is perhaps the best proof that
can be given of its utility. The inventor has received
certificates from the bookbinders alluded to, which will be
sent to the Society, if they think the press worthy of their
notice. “Mr. Hardie, in desiring . me to submit the model
to the” inspection of , the Society, has i in view chiefly to be.
nefit the bookbin ders i in places remote fr om his residence,
an object which he thinks cannot ‘be so well. attained in
any other way, as by the publicity which the Society i is
able to give to im provements deserving of its notice.
“* From their Transactions. for 1806, .
264 : "The
~
oy eA
pa ne a A
~j
TS
a ee ee
be
DCD’
\N
\
CDW
ON BLENDE. S3T
The improvement of this simple instrument has cost Mr.
Hardie much time, and even expense; and he will be glad
to receive any remuneration from the Society which they
may think his invention deserves.
Iam. Sir,
Your most humble Servant,
A. TILLOCH.
; To CG qiitidieton, M. D.
Twenty-three persons testified by their iebieiAiacs and
subscriptions to Mr. Hardie their approbation of his Cut.
ting Press.
Reference to the Engravings of Mr. J. Tarde Booka
binder’s Cutting Press. Plate X. Fig.
The principal difference between this and the press which Description of
the press,
has been from time immemorial employed by the book.
binders consists in effecting the business by one iron ~
screw, instead of two wooden ones formerly used. This
screw works in a nut let into and screwed to the top
piece A, its lower end working in a collar, screwed to the
moving piece b, sliding in grooves within the two sides of
the frame. CC are the guides for the plough, as in the
common press.
VI.
On Blende, and some other Articles ; ; by Prorrssor Proust*,
‘Tuar zinc is incapable of disputing oxigen with eharcoal, The zinc in’
isa known fact: and the same may be said of sulphur. ; Blende Balik
Consequently, if blende contain oxigen, it must yield it to
the action of charcoal.
I kept a mixture of transparent yellow blende and fir
charcoal at a red heat for an hour, but I did not find the
slightest indication of sulphurous acid. The mixture being
washed, to separate the charcoal, left the blende behind,
which had undergone no change. Where then is the
exigen of blendes?
* Journal de Phy lage Vol. LXIV. p, 150, Feb. 1807.
I have
338
and the meta!
in it saturated
with sulphur,
Artificial sul-
phuret of zine,
38 parts sul-
phur to 100 of
zinc.
Transparency
of a sulphuret
no proof that
the metal is
oxided.
Sulphuret of
arSENICe
ON BLENDY.
T have heated redhot a hundred parts of the same biende
with as much sulphur; and, when the operation was ended,
it had not increased a single grain, or even changed colour.
Hence we may conclude, first, that the metal in blende is
saturated with sulphur; and secondly, that it is free from
oxigen, otherwise the sulphur is a combustible, which
would have taken its oxigen from it. The following ex.
periment does not allow me to doubt this.
I heated together a mixture of sulphur and pure oxide of
zinc, a hundred and twenty-five grains of each: the pro.
duce was a hundred and thirty-six grains. Apprehensive
however, that it might not be saturated, I heated it with
fresh sulphur, by which it was increased to a hundred and
thirty-eight. grains. On heating it with sulphur a third
time, it did not go beyond a hundred and thirty-eight. I
repeated the experiment twice more, and the product
‘stopped at a hundred and thirty-eight grains. Hence we
may infer, if there were no mistake, that 38 paris of
sulphur took the place of 25 of oxigen, that were con.
densed in the oxide. It would be superfluous to say, that
this process evolved torrents of sulphurous gas.
Morveau is I believe the first, who reproduced sulphuret
of zinc by heating its oxide with sulphur. The artificial
blende remains pulverulent: but it appears to me by Mor.
veau’s account, that it is capable of being melted by a
strong heat. Blende is transparent; hence, they say, its
metal must be oxided. But the sulphurets of mercury and
of arsenic are transparent likewise; yet they are free
from oxigen. The sulphuret of arsenic, I know not whe-
ther I have mentioned the fact, supports any temperature
to which you choose to expose it, without affording any ._
indication of sulphurous gas, or losing its transparency.
Arsenic acid or oxide gives out sulphurous gas in abundance,
when heated with sulphur, and affords a transparent sul.
phuret, similar to that produced by the metal itself. These
compounds therefore contain no oxigen ; and consequently
transparency is no argument for the oxidation of a sulphu.
yet. But why should zine refuse to unite directly with
sulphur? I confess I see no reason for jt. I had intended
: te
HIDROSULPHURET OF ZINC. 339
’ to treat zinc with cinnabar, and other sulphurets; but dif.
, ferent objects have prevented me.
_ _The sulphuret of zinc is frequently concealed by foreign Different co-
oxides and snlphurcts: hence red, black, ash-coloured, !ou"s 40 not -
constitute spee
green, and other blendes, of which so many species have cies in blendes,
been made. Now this is precisely the same, as if, in the
natural history of wool, different species were to be made
of those that are dyed red, black, gray, or green.
There are blendes Falplire by red oxide of iron, which Black blendes
; p coloured by red
_/appear black; but their powder is red. These may be oy iae of iron,
“analysed by muriatic acid, which will cause. the iron to
descend to its minimum of oxidation, on account of the
sulphuretted hydrogen formed during their solution. We
should be aware of this, that we may not suppose the
oxide to be at a minimum,. where nature has placed only
oxide at a maximum.
There-are some that contain lead in the state of oxide, Blendes with
or of sulphuret, If these be exposed to the action of !4-
‘muriatic acid, the whole of the lead is found in the solu.
‘tion: but if oxigenized muriatic acid be used, we must
look for the lead in the residuum only. ‘The reason of this
is obvious; the sulphur of the blende, being acidified, pre-
‘eipitates the lead in the state of sulphate.
Hidrosulphuret, of inc.
Mkkabytctiied hidrogen precipitates zinc from its solutions Hidrosu!phuret
in a yellowish white powder, which is a hidrosulphuret. of aias
-.This precipitation however is limited. When the acid is
freed from a considerable portion of. the oxide, so as to be
in excess, it disputes the remainder with the hidrogen, and
the precipitation stops. It is necessary therefore, to adda
dittle potash, to neutralize this excess. ‘The alkaline hidro.
sulphurets: produce the same precipitate. ‘The nitric acid
~ acts with vehemence on, this hidrosulphuret, burning its
hidrogen, and part of its sulphur. Muriatic acid applicd
coldiexpels the sulphuretted hidrogen in abundance. This
~-bidrosulphuret at a red heat gives out water and sulphurous
acid, and is converted into a simple sulphuret, or blende.
The suiphuret of zinc, whether native. or artificial, yields
«ulphuretted hidrogen ; which however is not an educt, but
@ product.
Ambergris,
340 ON AMBrreris, &o.
Ambergris.
Yellow amber- This piece was found on the coast of Brasil. Tt is of the
gris from Bra- | | 5 ay bee weil
‘ils colour of honey; ‘very homogeneous in its texture; and
; free from those fragments or beaks of the cuttlefish, that
aré interspersed in the ash-coloured amber of the shops. Al.
cohol dissolves it entirely, except a few slight pellicles.
This solution is curdled by water. Evaporated it leaves
: a yellow substance, which softens and burns like a resin;
| swims on a solution of potash, which dissolves but afew
atoms of it; and gives out no smell of ammonia. The fra~
grance of this purified resin is still that of the ambergrise
itself. Exposed to distillation it melts quietly, without
swelling up, and yields a thick, yellow oil, which swims
on water. It is accompanied with some indications of an
acid: but what is astonishing is the ambergris scent of this
oil, ea
Cochineal.
Cochineal acid. The powder of this insect has always seemed to me to
ad RR have an acid taste. I know not whether it be the effect of the
tated with lime, action of air on any.of its principles. Lime water pre-
cipitates its colouring matter completely, and the result is a
but obtainable lake, on which alcohol has noaction. To obtain the pure
more pure with colouring principle, we should decompose this lake: but as
oxide of tin or 2 i e 5 :
Jead. the white oxides of tin and of Jead likewise saturate them.
selves with it readily, we may obtain it still more pure from
these by means of sulphuretted hidrogen, than by employ.
ing acids. JT believe the colouring’ principle — of kermes
likewise precipitates with lime.
]
Ox gail.
Resin of gall. Acids precipitate from this a resin, which, after it has
. been well washed in boiling water, may be drawn into
threads like boiled turpentine. When dry, it is semitranss
parent, greenish, melts with the gentlest heat, and on
burning coals exhales a smoke that has somewhat of a fras .
grant smell. Alcohol ‘dissolves it, without leaving any ~
residuam; and water precipitates this solution. - Oxigenized
muriatic acid whitens it with the assistance of a gentle heat.
Tt remains in complete fusion, after having given out some
moisture
LEVELS OF FRANCE. 244
thoisture: and a strong heat c2uses it to rise in the form of
a thick oil, the smell ‘of which is that of an animal sub-
stance, and unpleasant. A little carbonate of ammonia
accompanies it. It leaves very little coal. But what dis- soluble in
tinguishes it from the aromatic vegetable resins is its great @kalis.
solubility in the weakest alkalis. Acids separate it from
these without alteration, and it may be drawn out into Not always the
threads as before; so that we cannot deny it the principal same.
characters of resins, but it is not always the same. I have
obtained some from gall, which was soft, semifluid, or in«
capable of assuming the consistency of the preceding.
‘To obtain this resin pure, we must begin with passing Mode of ob-
dried gall through alcohol, to separate its albuminous por- ‘98 it Pure, ~
tions. ‘These occasion the putrefaction of gall when kept: ana preserving
but the extract, passed through alcohol, and evaporated to oe ie
the consistence of a sirup, is no longer susceptible of alte.
ration; and it is in this state I keep it for my lectures*.
Vil.
Remarks on the Structure of Mount Jura, from a@ cone
siderable Number of Heights taken by the Barometer,
and extended through France to the Sea; by Mr. Anp.
bE Gx, Member of the Academy of Cassel, &c.t”
1 ae four loftiest summits of the first chain of the Jura First chain of
are nearly on a level, as is their base, the lake of Geneva, ™ount Juri
‘on a length of twelve leagues. ;
The summits of the Suchet and Sucheron, which rise from
the western extremity of the lake of Neufchitel, six leagues
from the preceding, are 30 toises lower. The other sum.
_ * An ingenious artist, Mr. J. Clark, in his Instructions for Draw-
ing and Painting in Water Colours, observes that gall, which it is
frequently necessary to,add to_a tint, when it will not adhere uni-
formly to the paper, from any slight greasiness of its surface, will
keep much better, if it be boiled a little. This no doubt is owing
to the coagulation and separation of the albuminous matter by heat,
conformably to the remark of Professor Proust. W.N.
* “¢ Journal des Mines Vol, XVIII. p. 430, :
e
j mite
$42 LEVELS OF FRANCE.
mits continue diminishing to the Rhine; but to the Lebres.
berg, five leagues below Soleure, or through a.space of 25
or 30 leagues, they decrease almost imperceptibly, as does
their base. In this interval indeed the summit of the Chas-
serale is not above 40 toises lower than the four highest ;
but from the Lebreberg to the Rhine the el is more |
rapid.
The plains or table-lands, that form the western foot. of
this first chain of the Jura, likewise diminish in height pro.
portionally to the mountains, and in the same direction, .
Secondchain. 2. The highest summits of the second chain of the Jura
continue nearly on a level with each other as far as the
Stierberg, opposite the Lebreberg, a distance of 20 or
25 leagues: but thence to the Rhine they also lower more
aaree like those of the first chain.
Third chain, . The highest summits of the third chain are tt on
a og with each other throughout its whole length, which
is 30 or 35 leagues.
Fourth chain. 4. The highest summits of the Sountls chain, which are
nearly in a right line from Estival, four leagues north of
Moirans, to St. Hippolytus, a distance of 20 or 25 leagues, -
are likewise nearly on a level; but those to the south of
Estival, and to the west of the above line, follow the ins
clination of the rivers.
There are several large plains that iatersect this chain,
particularly above Ornans and Villafans. These plains are
nearly level throughout.
Fifth. 5. The fifth chain is very similar to the focarties
Sixth, or lowest- 6. The lowest chain of the Jurais about 60 leagues in
a. length. . Its loftiest summit is that called the haut des Tron-
chats, three leagues east of Porentrui.. From this point
the other summits diminish on both sides, according to the
course of the rivers. There is no great difference from the
mountain of St. Ursane to the Mont de Triéve, two leagues
north-east of Beaume: they afterward diminish more, and
_ remain on a level with each other to the mountain- of
Pouillat, three leagues north-east of Bourg-en-Bresse, that
is for 35 or 40 leagues.
. The plains at the eastern foot of the last summits are
also nearly on a level with each other,. particularly from
Orgelet to Cernans, above Salins.
From
‘LEVELS OF FRANCE. 343
- From this arrangement it follows, that tlie whole of thé The whole |
Jura forms an amphitheatre of 60 leagues long, by 12 or 14 Atalay
broad, the steps of which, or chains of mountains, that
rise above one another in a line from north-east to souths
west, are level, each almost throughout its whole length.
%. In the chain that separates, the waters that fall into Chain that
the two seas, the loftiest summits, except the Haute. Joux apatite Ng
VAiguillette, are in the neighbourhood of Dijon. From
this poimt, following the chain to the south-west, the
highest summits are nearly on a level; but the other sum.
mits of this chain decline to the north-east.
Dijon and Besancon are level with each other, and the
highest summits in the neighbourhood of these two cities,
separated by a plain of 14 or 15 leagues and a few hills,
are likewise ona level. The summit called Tasselot, the
highest near Dijon, is 306 toises above the sea: the rocks
of Montfaucon, the highest near Besancon, are 303 toises
above the sea. The other summits to the south-west of
Dijon and of Besangon, in the two chains in which these
' cities are situate, are likewise on a level in their other
corresponding points on each side of the Saone, at 12 or
13 leagues distance, and in a length of 20 leagues.
8. If all the valleys were filled up to the height of the General level
summits of the mountains that border upon them, from the il eae or"
sea to the tops of the Alps, a very gently inclining plane the Alps.
would be formed. For instance, if a right line were drawn
from Havre to the loftiest summits of the mountains, that
form the groupe of St. Gotthard, it would cut the inter.
mediate chains of mountains nearly at right angles, passing
two leagues south of Paris, between Langres and Dijon,
five leagues north-east of Besancon, two leagues north of
Neufchatel, and a little to the west of Berne.
This line would be 160 of the old common French leagues
in length [445 miles], and the whole ascent would be only
1750 toises [3733 yards], the height above the sea of the
-Giaetscherberg*, the loftiest summit of these mountains;
0 that if the declivity were uniform, it would be -a little
_ * The height here given is not from actual measurement, but
estimated froma comparison with them that were measured,
leas
SA4 MINERALOGY OF ARRAN.
less than 11 toises per league. But, as the whole slope is
not uniform, to give a more accurate idea of it, we may
divide the 160. leagues into five unequal portions, each of
which would have a nearly uniform slope. —
Level from Ist. From Havre to the chain that separates the waters
a fe falling into the two seas, taken near Dijon,*a length of
95 leagues, with 300 toises elevation above the sea, which
would give an-ascent of three toises, one alee! four inches,
in every league. .
From Dijon to Qd. From these summits to those of the lowest chain of
He a the Jura, beyond Besancon, at both which places the height .
above the sea is the same, making a horizontal me of 23
, leagues.
From Besangon 3d. From the highest summits near ee to those of
ee of the highest chain of the Jura, at Casserale, two leagues
north of Neufchatel, a distance of 12 rile 550
toises difference of elevation, giving 4542 toises rise in a
league.
From the Jura 4th. From the “loftiest summits of the highest chain of
tothe first . Jura to those of the lowest chain of the Alps, south-east of
ehain of the
Alps. Berne, a distance of 15 leagues, with 200 toises difference
of elevation, giving 13 toises two feet rise in a league.
From the 5th. From the summits of the lowest chain of the Alps
cabins ey to the highest of those of St. Gothard, 15 leagues distance,
: * and 700 toises of elevation, being a rise of 46 toises four
feet in a league. . .
Vill.
Some Mineralogical and Geological Observations, made in
the Isle of Arran; by the Rev. James Heapricx*,
A DVANCING along the north shore of the island from
Loch Ransa, the first remarkable thing that occurs is at
Craig-na-Srone (Nose Rock,) where the secondary strata
are scen resting upon the micaceous schistus. The first
_% From that Gentleman’s View of the Mineralogy, Agriculture,
Manufactures, and Fisheries, of the Island of Arran. .
Stratum
MINERALOGY OF ARRAN. 3845
stratum of this kind is a sort of chalky limestone, which Calcareous
contains reunded pieces of quartz, fragments of schistus, a a
&c., so as to constitute a species of pudding stone. Many
parts of the stratum contain few of these extraneous bodies,
and would make excellent lime. Further on, a sort of
pudding stone, red sandstone, and shiver, occupy the
coast. ~
Where the limestone rests upon the schistus, three whin- Schistus inter-
stone veins intersect the schistus, and the strata that rest Feb eli
uponit. Where these veins run in the schistus, the cheeks
on each side are penetrated by the whinstone; and frags
ments of the schistus are found immersed in the whinstone
veins. One vein divides into two, like the letter Y ; and
pieces of slate are found immersed in the whinstone, at the
angle of separation.
The Scriden rocks are strata of breccia, or puddingstone, Rocks fallen
of most enormous thickness, and leaning upon the side of nel
the mountain at an angle of about 45°. About a hun.
dred years ago, immense masses fell from these rocks, and
now encumber the beach, rendering it difficult and dan,
gerous to pass along shore. The concussion shook the
earth, and the sound was heard in Bute and Argyleshire.
. On climbing towards the summit, found the whole of this
_ enormous mass of strata, which reaches almost to the top
of the mountain, had shifted from its original position;
and that its transverse sections were separated from each
other, so as frequently to leave spacious gaps between,
In many cases too, the upper masses ride upon the ends of
those below them; which, having no visible support, ex.
cite the most lively apprehension that the whole is about to
“fall, and crush the beholder to atoms. The Scriden rocks
are reckoned the extreme point of Arran, towards north-
east.
_ Red sandstone, with sometimes pudding stone, continue Sandstone and
along the coast, and ascend to the top of the mountain en ire ee
where they meet the schistus.
_ Near the Cock, these strata are intersected by a great intersected by
vein of porphyry, the south-east side of which consists of porphyry.
rhomboidal, sharp-angled crystals of feldtspar, inserted in
a red ground. On the opposite side, the ground is mostly
Vou. XVII.—SuprLement. 2 4 blue
346
Different sbe-
cies of por-
phyry in one
mass.
Cock, a huge
mass of sand-
stone.
MINERALOGY of ARRAN,
blue basalt, with some streaks and spots of red intervenitig,
This vein scems to rise to the top of the mountain ; and it
exhibits a curious specimen of different species of porphyry
combined in the same mass. I do not see how the igneous
theory can account for it; because, had it been raised from
the bowels of the carth in fusion, it ought to have been
homogencous in its structure. The variety and separation |
of materials show they had been conveyed into a chasm
in the strata, at different times, and from different sougces ;
where they. consolidated, by the attraction of cohesion,
which operates upon bodies whose particles are brought
into close union, by extreme pulverization. The earths,
too, when minutely pulverized, combine with water, and
pass from it, either in the form of cement to unite the
grosser particles, or in the form of crystals. One point is
clear, that the feldtspars in this porphyry had not, like
those we have so often described, been conveyed to their
present situation in a solid state, because their angles are
not blunted, or worn. They must therefore have consoli-
dated where they are now found.
The Cock is not a solid rock, as I expected, but a oc
nass of sandstone that has fallen from therocks, and stands
on a narrow base upon the beach. It has acquired this
Red sandstone
intersected by
basaltes.
Red indurated
efay, capable
of a fine polish,
and being
wrought into
ornamental
vessels,
name frommariners, to whom it serves as a land-mark, and
to -whom it presents avery lively representation of a cock
crowing, and clapping his wings.
Contiguous to the Cock are irregular veins of basalt
intersecting red sandstone, of a dark blue colour internally ;
but the sides next the sandstone are of a deep-red colour,
smooth and glossy like Roman bricks. The’ breadth of
these veins varies from about one to three or four inches.
Further‘on, the same sort of veins occur in red os
clay shivet. ;
Several massy strata of indurated clay occur, of a florid
red colour, to which the sea has conveyed a fine polish.
From these, I am confident, vases, urns, jars, and all the
more durable species of earthen ware, might be fabricated,
. susceptible of a jaspidean polish; and, being variegated
with spots of different colours, might emulate the most
elegant porphyry. si AR }
~ Within ©
MINERALOGY OF ARRAN. 347
Within tide are several strata that look like a Mosaic Lee Mosaic
pavement of finely polished brick, of a florid red colour. Renee
Dhey consist of equilateral pieces, or rhombi, of indu-
rated clay, divided by septaria which run in straight lines
parallel to each other, and are crossed by other straight
and parallel lines with the greatest regularity, so that each
rhombus is enclosed within septaria, which separate its
sides from those of other rhombi, which are parallel to
them: The breadth of the rhombi may be about fourteen
inches; that of the septaria about half an inch. The
colour of the septaria is a pale red, inclining to whiteness ;
and it looks very like puzzolana cement, in the interstices
between regularly formed stones. In many cases the pave-
ment is worn down; but the cement, which is harder, pre.‘
serves a regular equality of height.
I doubt much if the most skilful mason, or even a mas
thematician, could produce any thing more regular, or
more beautiful.
Here are numerous strata of red clay shiver, and of red Iron ores,
Slaty schistus, which include various stratule of hematites,
and of kidney ironstone. The hematites is generally ar«
ranged in stratule, but often interspersed. When stratified,
it generally comes off in rounded pieces, whose sides are
perpendicular, and are thicker towards the centre, thai
towards the circumference. When interspersed, the pieces
‘are generally broader, are of a round, or oval form, and
Hattened towards the circumference.
_ The pieces that have been long exposed to the air are of
a blood-red colour, though darker towards the centre.
But by a little digging, pieces are found, with a red teg-
men, but internally ef a fibrous texture, ‘the fibres at right
angles to the breadth of the stone, and the colour that of
‘steel. The interspersed pieces often exhibit an indented
fracture, where the surface e indentations has the lustre
of stecl.
The kidney-form pieces often exhibit a dull red earthy
‘appearance to their centre. But, where they have not
been too much exposed to the atmosphere, they discover a
"radiated texture, with the lustre of steel.
These two species feel very heavy; but there are also
? ZA | ether
B45
:
Used for mark-
ing sheep,
Imbedded in
clay, under
peat, on the
summit of the
mountain.
Blood-red lime-
stone.
Jaspidean
marble,
Change to
Sandstone.
MINERALOGY OF ARRAN.
other stratula, which, though good iron stone, seem to
contain a proportion of clay, and do not feel so heavy.
The people here call this ironstone keel, and use it for
marking their sheep, and various other purposes. It has
a greasy feel, and gives a stain to the hands, which it is
difficult to wash off. “
The farm of Cock is on a steep bank projected from
the side of the mountain. The soil is mostly of a blood.
red colour, and is. composed of the debris of the schistus,
and of the ironstone which it includes. It is wholly en
cumbered with this ironstone. Where burns had made
excavations, I traced these ironstone strata to the summit
of the mountain. .
What is most extraordinary, great quantities of this iron.
stone are found, imbedded in clay, below peat bogs, on
the flat summit of the mountain. This clearly shows that
the summit was formerly covered by strata of red schistus,
including ironstone, which have mouldered down. Much
of the clay-may have been washed away, leaving the irone
stone, which water could not easily carry from a flat
surface. / veel '
Connected with the latter, are several strata of limestone,
of a florid brick, or blood-red colour. Such limestone
always occurs, where hematitical strata present themselves
along the coast. We shall therefore take no further
hotice 6f this limestone, until we reach Currie, beyond | |
which it was not observed.
A stratum about three feet in thickness, and formed
into blocks of from three to four feet in length, attracts
attention. This stone contains innumerable shells, chiefly
madrepores, somé of which exhibit a bright crimson
colour. The ground of the stone is somewhat calcareous,
and in its fracture every way resembles jasper, of a chocde«
late colour. It may, not improperly, be called jaspideam
marble. Were it polished, it would exhibit a striking ape
pearance,
Advancing onward, the strata upon the beach are sud.
denly changed. White and grey sandstone, with sometimes
a mixture of yellow, occur, and are continued a great
way,
2 In
MINERALOGY OF ARRAN. Ag
In these the Cock coal is included. - It is confined within Coal.
an angular space, formed by two ledges, or edge-seams of
limestone, one from north-east, the other from south-east,
which meet at righteangles. To the north and south of
these ledges of limestone, though the white sandstone ex.
tends a long way, and includes numerous beds of black
bituminated shiver and blaes, no stratum of ‘coal has been
found.
There are three or four seams of coal running parallel seg he
from north to south; the principal, or main seam, being years ago,
about fourteen feet in thickness. They dip nearly to-
wards north-east, at an angle of 45°. Pits were sunk,
and efforts used to work this coal, about fifty years ago ;
but as there is no harbour to export by sea, and a road
must be cut several miles through rocks, a salt-pan svas
built, to consume the coal in the manufacture of salt.
The undertaking seems not to have succeeded, and was
soon abandoned.
~The coal is of the same species with that at Kilkenny in A blind coal
eetand ; and there are similar strata in Ayrshire, in Fife- ae ote
Shire, and various parts of Scotland. Itis blind coal, of uncommon ex-
uncommon excellence. It is not'so apt to fall into powder <<
as most other species, and, when fresh dug, it exhibits a
metallic flustre. It is hence called glance coal by some;
but this word does not distinguish it from some of its own
varieties, which have no lustre; nor from some species of
bituminated coal, which have a shining appearance. The
word blind coal is more expressive of its peculiar property,
in emitting neither flame nor smoke ; as it consists of ~
carbon, Ww without any impregnation of ituinen.
TI could not learn that the working of this coal’ was Why discon
abandoned, because it ‘soon disappeared,’ as stated by il
Mr. Jamieson, p: ‘101; but that, from ‘its ‘inaccessible
‘situation, they could not work it with profit. Boiling
salt could hardly absorb their refuse, far léss such a quan.
tity as would keep the pit constantly going. It is well
known, that if there’benot a demand sufficient to absorb }
all that is turned out, ‘no coal ‘can bé worked ‘with profit;
and that the working cannot be abandoned and’resumed, _
according to ‘the ‘fluctuations of the demand ; “because, in
that
350
No basaltes
in the coal
field. -
Mistake of the
miners.
Siliceous sand-
stone bent into
Gothic arches.
~ Course of the .
tozl, and mane
MINERALOGY OF ARRAN.
‘that case, men’s wages would be running on, the machinery
would be rotting, while the pit would be drowned with
water.
Mr. Jamieson also states ‘ the great frequency of basalti¢
veins as another cause, which must render the coal, if it
should ever be detected, of an indifferent quality, and dif-
ficult to work.’
With regard to the basaltic vcins, I remarked it as an
uncommon circumstance in Arran, that I could: not find
a single basaltic vein in the coal-field, or-as far as the white
sandstone extended on each side of it. There did not there-
fore appear to be the smallest ground for believing that the
coal was cut off, or its quality injured, by basaltic veins.
When they wrought the main seam, by digging along'its
outcrop a large open trench, they came to the strata which
form the steep side of the mountain, and which here rise
at an angle of nearly 70°.. They thought the coal ex-
tended through the base of the mountain, and cut a mine
to foliow it out. Had they bestowed the slightest attention,
they might have seen, that the strata on the side of the
mountain are very different from those which include the
coal; and that, when the latter touch the former, they
suddenly terminate. The strata on the side of the moun.
tain appear to have been of much carlier formation, and
they rise ata much higher angle, than those which include
the coal. Nor does it appear that the quality of the coal
was in the least affected by its approach to thé mountain;
for it was equally good until it was cut off,
On examining the strata perforated by their mine, I
found them to be siliceous sandstone flags, of great hard-
ness, and of a brownish white colour, their surfaces ex.
hibiting micaceous scales. ,, They.are from one to two inches
in thickness, and are curiously bent upwards, into the form
of a Gothic arch, or.rather of a great many arches over-
lapping each other, which form the. roof of their mine.
It was-useless to follow the coal from the strata where. it
was found, into strata so very different, both in quality
and position. As far as I could learn, the coal only failed
them here, where they had no right to expect it.
From the position of this coal, there can be.nodouht
but
MINERALOGY OF ARRAN. 351
but it expands to a great extent below the sea. If ever it nerinwhichit
should be
be convenient to work it, I conceive it should not be by wrought,
sinking pits, but by sinking in the stratum itself, and draw.
ing it up the inclined plane of sandstone, on which it rests,
by carriages running upon rollers.
This coal, being esteemed pure carbon, and capable of With the iron. ©
ducing t intense heat, I am s dit n agg ne Ent Re
producing a most intense heat, urprised it meyer has _ a. marys
been applied to the smelting of iron, and other fornacic able.
uses. The ironstone here seems inexhaustible, and of
excellent quality. A harbour might be scooped out of one
of thé ledges of limestone, which enclose the coal-field;
which would cost nothing, as the limestone would repay
‘the expense with profit. rom this, the coal and ironstone
might be exported to a situation favourable for an iron-
work.
Some strata of hituminated shiver, or shale, of a black Bituminous
colour, are visible, not only in the coalfield; but many ‘2!
_are visible, for a great extent, on each side of it. These
strata sometimes throw out an efflorescence of sulphate of
mlagnesia.
But in one of the seams of coal which Mr. Cena had A stratum
wrought in the way called open stretch, for the purpose of mgt EDs
burning limestofe, I observed a ably bituminated species tumen between
of till, of a black colour. This appeared so extraordinary, ilaety is
that i requested Mr, Cowie to write down a description of
it, which follows.
‘The seam of coal, at the Cock of Arran, wrought by
James Cowie, is first about ten inches, then eight or ten
inches of a dauchy till, then twenty inches of coal. The
dauch which separates the two seams of coal, is arranged
an dhisemaniner SSS55 like the back-bone of :a
‘fish, and rises in large pieces, but parts in the middle. The
= between the two seams of the coal serves to burn lime.’
“Mr. Cowie added, that the dauch was always mixed with Mixed for
“the blind coal in presi lime. That it seemed to kindle Uns lime.
more readily than the coal; and the only difference was,
that the dauch always left a large guest (cinder); whereas
the coal burnt into a fine white ash, of very smal} quantity.
Here, then, are highly bituminated strata of clay, not
only connected with blind coal, but one interposed between
two seams of that fossil.
§ Our
B52 MINERALOGY OF ARRAN.
Remarkson the Our men of fire make their favourite element operate as
vulcanean ated : 3
theory. many contradictions, as the hocus-pocus tricks imputed to
phlogiston by the older chemists. At one time, phlogiston
could not penetrate the most porous bodies; at another,
the most dense were insufiicient to confine it. At one time,
it was the cause of gravity and attraction; at another, of
levity and repulsion.
‘These gentlemen assert, that blind-coal has had its bitu-
men evaporated, by the great heat which elevated the strata,
from want of sufficient pressure to confine it; and that
bituminated coal retained its bitumen, while subjected to
this heat, im consequence of the enormous pressure which
prevented its escape.
How camethe But I would ask these gentlemen—How came the clay
ke iy ae strata, in the same alternation with the coal, to retain their
thesis? ~—sO@dbitumen, while the coal was deprived of it? But especially,
how came a stratum of clay, included between two stratum
of coal, to retain its bitumen, while both the stratum of
coal lost theirs? I do not see how these gentlemen can
answer these questions, in a way COnaitenm with their
theory.
None in the They refer us ‘to the sandstone which i the blind
Fendi rpa ores coal, and allege we shall find some traces’ of the bitumen
, eepa'! But though I examined the sandstone strata which
- forthed thé immediate roofs of the strata of coal, and many
others, with the utmost care, I could not find the smallest
visible trace 6f bitamen-in them: nor could I'trace the
slightest mark of vegetable impression, either in the sand-
stone, or in the bituminated shiver connected with the
blind coal. , .
Bituminous Bitumen, particles of coal, and remains of vegetables,
rs! formed J have always found in the sandstone strata that covered
romvegetables, ‘ : ; ,
bituminated coal; and often, in the coal itself, vegetable
remains occur. Hence, I inferred, that such coal had been
formed from vegetables; and the marks I formerly as-
signed of sandstone, including coal, applied only to bitu-
blind coal net. Minated coal. Blind coal appears to be suéz generis, and
to have been formed without the aid of vegetables. 4
But without pretending to assign the mode of its for-
mation, 1 think I am warranted to assert, it was not
formed
MANAGEMENT OF VINES AND WINES IN CHAMPAGNE,- 353.
formed in the way our fiery “philosophers allege; and that.
the facts stated are fatal to their theory, as far as it depends
upon pressure, or defect of pressure.
. Phe strata of white sandstone, and of bituminated shiver,
occupy the coast only a short way, on the north of the coal
field; but on the south they prevail for several miles.
TX.
Questions respecting the Vines and Wines of Champagne, by
_ Mr. Cuartar, with Answers to them by Mr. Germon,
of Epernay*.
‘Tue country that produces the celebrated wine known Red and white
by the name of champagne is particularly famed for-two peer
kinds; the white, called wines of the river Marne; and
_ red, or wines of the mountain of Rheims. If the southern
aspects of the hills on the Marne produce excellent white
‘wines, their backs and declivities, called the mountains of
Rheims, though generally facing the north, and almost.al-
ways the east, yield red wines of good and sound quality,
and of a fine arid high flavour, which. ought to be made
known.
The side toward Rheims is divided in trade heehee, Si isiohs antes
the quality of its wines into the mountain, lower mountain, EN quali-
and St. Thierry. Of the first those of Verzy, Verzenay,
* The numerous facts here given render this Paper valuable,
though the Author’s theory and expressions are not always on a les
vel with the present state of chemical knowledge. Nothing how-
ever more perfect, or more copious, has yet been published, res-
pecting one of the three principal wine-countries in France. - Mr.
Chaptal will introduce almost the whole into his. Art of Making
Wine, which will appear in the course of the year.
[We have considerably abridged this Paper, from the Annales de
Chimie, vol. Lx1, p. 5, for January, 1807, taking only the princi-
‘pal facts; which we apprehend will not be unacceptable to many
of our readers, as the practice of making wines for doniestic use
has much increased of late years; and many hints for the manage-
ment of wines, ‘and of the vine, may be derived from the informa-
‘tion here given-by a man of muchipractical knowledge]
mds ‘ and
354 MANAGEMENT OF VINES AND WINES IN CHAMPAGNE.
and Mailly, are most esteemed: the rest, though good, are
not equal in quality. The vineyard of Bouzy, which ter-
minates the chain, and the horizon between the south and
east, so that it belongs to both divisions, must not be omit-
ted. It produces excellent red wines, participating, from
its situation, in the good qualities of those of Verzenay,
and the good red wines of the Marne. ? :
The lower mountain compriscs a great number of vine-
yards, among which are distinguished those of Chamery,
Fceuil, and Villedemange. The latter in particular’ pro.
duces wine in a favourable season, that will keep ten or
twelve years. This division extends to the banks of the
Aisne, but it produces only common wines.
The wines of St. Thierry are very pleasant, of a light
colour, and much sought after in commerce. But the clos
St. Thierry, from the archbishopric of Rheims, is the only
one that unites the colour and flavour of burgundy with the
lightness and briskness of champagne. It is to the cham-
‘pagne wines what the Clos-Vougeot is to burgundy.
What is the The best aspect for vineyards is unquestionably the east
sh for and south. Of situations the midway ofa hill is preferred,
as the heat there is more concentrated, while it is exempt
from the variations of the air on the summit, and the damp
vapours of the foot. A western aspect is unfavourable to
vegetation, which it burns and dries up: so that a vineyard
with an eastern aspect is more valuable by one third.
What is the Next to aspect in importance, if not before it, is the na.
best soil & ture of the soil. This should be light, sandy, and granitic ;
neither compact, close, nor clayey. In general the vine.
yards of Champagne have a substratum of chalk: a kindof
soil on which the vine grows slowly, but when it js once
thoroughly rooted on it, it thrives well.
/Whenandhow The vines are planted in November or December, when
are-the vines the weather permits. An oblong hole or trench is made a
inert foot and half deep, and two or three fect long. Into this
the plant is introduced, and covered with earth, inclining
itso, that only two or three inches of the extremity rises
above the surface ; and this extremity is refreshed by cutting
it lightly in a horizontal direction. These trenches are
made in rews, afoot and half from each other in strong
. grounds,
MANAGEMENT OF VINES AND WINES IN CAAMPAGNE 365
grounds, and two feet in light. A distance of three feet is
left between the rows, ‘and the plants in one are placed op«
posite the-intervais of the other.
They are propagated by layers: for which purpose:a propagation by
turf should be cut from a meadow, or amarsh; the branch !ayers.
to'be laid should be introduced into a-hole made in the mid«
dle of-this turf, and then fixed in the ground with it, ina
sloping position. The root will form in the course of the
year, and then the layer must be cut off close to the stock,
and taken up with its turf.
.| Grafting is almost out of use. The fruit indeed is larger, Grafting dis-
but it is much more liable to fail from the slightest misma. ¥S¢4-
nagement, does not produce so sound a wine, and the vines
do not last so long by far. .
A good vineyard will continue to produce well for fifty How long does
or sixty years, and frequently more, if well managed. If* “iey2"d last?
the layers be not planted deep enough, the vineyard will be
covered with trailing roots, forming a sort of floor, so that
there will be no place to lay down fresh shoots, and it must
be broken up.
For white wine black and white grapes are planted indis- What grapes
criminately in the same vineyard, which is perhaps wrong, paste oc
as they do not ripen at the same time. But wine made en-
tirely from black grapes would be too strong, and apt to
become pricked in hot years: and entirely from: white it
would be too mellow, as these praree* contain more muci-
‘Jage than the black.
The kinds of grape cultivated are not many. The black Black geneity
are generally preferred for several reasons. ‘They are not Mae cas
so soon spoiled by frost or rain, which are common about
vintage-time; and they give more strength and body to the
wine. Yet there are some places, where the wine is much
esteemed, though they have few black grapes.
As there is no danger from the frost in spring but at sun- Danger from
rise, an-eastern exposure has most to apprehend “from it, SPtIS frosts.
.but no aspect is exempt from the danger. No means of
_ guarding against it have yet been discovered.
On resuming the labours of the vineyard, about the end Management of
of February or in March, the first thing to-be done, and ‘He vincyard.
one of the most essential, since on it depends the greatness
s of
356. MANAGEMENT OF VINES AND WINES IN CHAMPAGNE,
Pruning. of the crop, is to prune the vine. When itis strong, two
side shoots or branches may be left: if weak, only one.
Three eyes should be left on each shoot. Sometimes thé
toi! vinedressers leave three shoots, and four eyes to a shoot.
If the vine be young, and the stock is not loaded with old
euttings, its height when pruned is only three or four
inches. The branches are never sufiered to shoot up above
a foot and half.
Digging. ‘After this pruning, about the end of March, or in Aids
whes the earth is softened and rendered pliable by the win-
ter frost, it is dug up about a foot deep, so far as to mn.
Putting down cover the roots, and all the clods are well broken. After
layers - this layers are put down where necessary, throwing on
them a basket of dung, and filling up the trench with mould 5
so as to let the two or three stems left on them appear above
ground four or six inches apart, and taking care not to ine
Stirring the jure the buds on them. Atthe end of April, cor in May,
ground, the earth is stirred again, but more superficially. | While
Stopping the the vine is in flower, it must mot be touched: but when this
Sich and is over, in June, the shoots are to be stopped at about @
3 foot and half ; and the vine is to be staked, and tied ‘up,
but not so as to interrupt the circulation .of the air, or the
- devélopement of the shoots. When this is done the earth
Stirringthe has a second stirring, and about the middle of August, it
ground again. hag its third and last. Oe SVE” viet tae
Ripeness ofthe | About the end of September, or later in some ‘seasons,
Sane the grapes will be ripe; which is known by the footstalk of
each being brown and woody, as well as the general stalk ;
the grape coming off easily, and the part of the stalk. sith
it not appearing green ; and the stones being brown, ary,
and not glutinous.
Gatheringthem Great care is necessary for making the white. wine. "The
for white wine. yinest and soundest bunches ‘must be carefully gathered,
i
large baskets, covered with a cloth ‘to keep the ‘sun from
them, car’ ried into the shade, and there kept mM the even.
. ing, ‘when they are to ‘be pressed as speedily as possible.
Pressing. | The grapes being laid’on the bed of the press,’ they” are to
be covéred with three or four layers of flat stones, and the
Spee tur ned. “When the J er has ran for four o or r five mi-
“utes,
freed from all dry, rotten, and bruised grapes, “put ‘into.
er ee nee ea
SF Oe ae eee
MANAGEMENT Or VINES AND WINES IN CHAMPAGNE, S57
nutes, ‘the press is to be turned backward, the stones re-
moved, the grapes that have protruded thrust into the heap,
the: <gones replaced, and the press turned again. Thejuice
from three of such pressures, which will not take up an
hour, is put by itself for prime wine into a vat, where it is
left all night to settle. —
* The next morning this juice is poured off from the sedi- Putting inte
ment, and put into new, matched, and well rinced casks, “*S**
In these it ferments, at first Galdh thy; afterward impercep-
tibly ; till, about the end of December, having gone through
all the stages of depuration, it becomes fine. It is then Racking and
racked off, in dry weather, and on some fine frosty day, *"%
and fined with isinglass. About a pound of that of Mar-
seilles is sufficient for 40 puncheons, of 200 bottles each.
The isinglass being dissolved is well beaten, diluted with
wine taken from the cask, then poured into it, and the
whole well stirred by an instrument introduced at the bung-
hole. The wine thus left to settle ferments slightly again, mI
till it is stopped by the cold w eather, or by time. Ina Second racking
month or six weeks it is racked off again, and has another Gn we
fining with half the quantity of isinglass.
In this state it usually remains till March, when itis bot- Bottling.
tled. Good glass bottles are taken for this purpose, well
rinced, corked with superfine corks, and these are confined
by packthread or wire. The bottles are then piled on their
sides, one upon another, in the.cellar. |
As the fermentation is not completely terminated at the.
time of bottling, it revives about the middle of Angust, be-
tween which time and the end of September it is not unusual.
to have five or ten bottles in a hundred burst; and this con-
tinues till the March following, when it becomes more vio-
lent, or more moderate; according to the state and quality
of the wine. In general, when not more than twenty
bottles in a hundred burst during the whole course of the
fermentation, the proprietor does not complain.
Fifteen or eighteen months after the first bottling, when Decanted inte
the wine has gone through all the stages of fermentation, ‘3h bottles.
and is to be sold or sent abroad, it undergoes a fresh dé,
cantation, which requires some dexterity. If the wine be
not mantling [mousseux], itis simpleenough. The bottle
is
a
358
MANAGEMENT OF VINES AND WINES IN CIEAMPAGNEs
is taken up in the position in which it lies; the wire is re#
moved with a hook, which the man holds in his hand ; the
cork is drawn; anda well rinced, empty bottle being held ©
perpendicularly to its mouth, the wine is decanted, leaving
at the bottom the sediment, which had not been shaken.
Some employ a siphon to draw off the wine in this ease.
When the wine is mantling, the operation is much moré
nice and tedious. Boards are prepared, with holes at cere
tain distances to receive the bottles, and placed near the
pile. A workman carefully takes a bottle from the pile, in
the position in which itlay; shakes it with a gentle, slow,
and regular motion, so as to get all the sediment down te
the side of the bottle, and thence to the neck, without mix.
ing with the rest of the wine; and then places it on ‘the
board in a sloping position. This is done regularly till the
board is filled. “Twenty-four hours after the bottles are
moved again in a less inclined position, so as to bring the
sediment down upon the cork. If this be done completely,
without rendering the wine at all thick, itis placed ina
perpendicular position, and the same is done with all the
other bottles. He then takes them one by one, bottom up-
wards, stays them with his left arm, removes the wire with
his hook, avd carefully draws the cork. The fixed air
expands ; the wine forces out the sediment into a receiver ;
when instantly the workman turns up the bottle, which has
Tet out only what was necessary to render the remainder
perfectly clear, and gives it to another, who fills it, and .
yecorks it,
Willkeep from This wine, when sent abroad, will keep ten years, with.
ten to thirty
years,
Gathering the
grapes for red
ae
out its quality being impaired: but in cellars, particularly
those of Champagne,whe are cut out of the chalk rock,
it will keep twenty or thirty years. The temperature. of
the cellars should be equable, and currents of air in them
avoided.
For making red wind; the grapes are gathered with the
‘same precautions as for making white, taking only the
black grapes. These are bruised in particular vessels, by
Treading them. men treading on them with strong wooden shoes: part of
Fermenting.
the stalks are thrown away, and the must is left in ‘covered
vessels to ferment suficiently to extract the colouring matter
frou
MANAGEMENT OF VINES AND WINES IN CHAMPAGNE, 359
‘from the pellicles. In some years three or four .days are
sufficient for this ;-in others it requires ten, fifteen, or even
twenty. '
. When the fermentation begins, the husks and sili are Management
forced down so as to be entirely covered with the must, gah “fermen
either by means of stout poles furnished with . cross. pegs 5
or, which is better, by a couple of stout men going into the
vat, and well treading and mixing its contents. . When the
air above the vat extinguishes a candle ; the stalks aud husks
rise forcibly, whatever pains be taken to sink them fre.
quently, that the must may not acquire a disagreeable taste ;
the must experiences a degree of real ebullition; and the
colouring matter is sufficiently decomposed: the. fermentas
tion must not be carried farther, lest the wine. acquire a dry
and hard taste, not to be cured even by keeping.
The liquor is then to be drawn off into another vat; and Pressing.
the marc pressed, but only twice or three times. What Putting inte
runs from the marc being well mixed with the other, the poe
whole is to be tunned into new, well. hooped casks, previ-
ously rinced with hot water ; -but these must not be quite
filled, as the wine still ferments for some days. As the
fermentation abates, they are filled up, and the bung, in
which a little hole is made, is putin. .When the fermenta-
tion is become imperceptible, the cask is stopped close;
care is taken to fill it up from time to time, for there is
soon a vacuity formed in it, and even to open the bung,
About the end of December, in dry weather, and if pos- Racking,
sible on a fine frosty day, because all fermentation has
ceased, the wine is racked off from the lees. About the
middle of May, before the hot weather comes on, it is
racked off again , and the barrels are fresh hooped, and the Second racking,
wine is put into the cellar.
When the wine’is to be sent off to the consumer, or put phird racking
into bottles, itis fined, For this purpose the wine is racked amd fining. —
off a third time; and the whites of five or six very fresh
eges.are well beaten up in a pint of water, without making »
them froth if possible, for every puncheon holding 240
bottles. Those for white wine hold only 200. This is put
into the cask, and stirred about, as in fining white wine.
The wine is generally bottled i in November, or thirteen Bottling.,
months
360 SENSIBLE TESTS OF CERTAIN ACIDS AND AMMONIA.
months after it was made. -Some excellent and generous—
wines may stand on the lees three or four years; but they
should be kept in barrels that will hold eight or ten hogs
heads, when the wine will feed, and be the better for it.
Keeps from six Good red champagne will keep in bottle six, eight, ten, or
to twelve years. ty olve years.
Management of In some places, the vines. are suffered to grow much
cinta higher than in others, or to about five feet, but this is
adapted only to a strong and vigorous soil. For this pur-
pose the strongest shoot of the vine is taken, all the rest
being cut off, and all the lateral shoots. This is bent
round in a complete circle quite to the stock, at the time
when the sap is most abundant, and the buds already open-
ed; and supported by an oaken prop six feet high, and an
inch square, to which it is fastened in two or three places. .
Laying down. Vines of this kind are propagated by laying down the old
stocks every ten or fifteen years, in a smalt long trench;
leaving on them three or four branches, which are likewise
buried in the ground. These will produce good ip for
the following year.
Produce greater. ‘The produce of these vines is gr eater, but the grapes da,
but nots d,
O80 20" ait ripen so early, and the wine in consequence is not quite
so fine and exquisite.
Se eS
X. ‘
On the most sensible Reagents for Muriatic, Carbonic, and
Sulphuric Acids, and for Ammonia: by C, H. Prarr,
Professor of Chemistry at Kiel*. . i
Sensible test of In the inquiry concerning the pretended formation of
rat ean a muriatic acid in water, by means of the galvanic pile, it is
unguestionably of great importance, to possess a very sensi-
ble test of this acid, that we may discover the first traces of
Nitrate ofsilver. it, and pursue its successive increase, Hitherto the nitrate
of silver has generally been employed. This reagent is no
doubt very sensible to this acid. Kirwan asserts, that one
part of the acid diluted with 108333 of water may be de=
- ® Annales de Chimie, vol. ux1,.p.19, April, 1807.
, tected
‘
a = eS
SENSIBLE TESTS OF CERTAIN, AGEDS AND AMMONIA. 36k
tected by, itsmeans ; but,this, test is greatly surpassed eae
the solution of mild nitrate of mercury prepared cold. One aes
part of muriatic acid of the specific gravity of 1°15, diluted
with.70000 parts of water, ‘barely exhibits a slight opaline
hue, .when tested with nitrate of silver. Diluted with
80000 times its weight of water; it eludes the action of this
test, as well as of all others, except the mild nitrate of mer-
‘ eury, which renders it very perceptibly turbid. Its sensi-.° Indicates
re = - : Seale CSRS
bility is so great indeed, that even zog555 Of agrainof mu- J09ce
cme) DOES
riatic acid at 1-15 is indicated by a slightly dull tint in the
water that contains this extremely small quantity. From
reflecting on the absolute insolubility, as it may be called,
of the mild muriate of mercury, I was led to experiments
concerning this reagent. |
It is at the same time the most sensible test of ammonia. Detects
One part of this alkali, diluted with 30000 of water, is in- res Koes aly
dicated by a slight blackish yellow tint, when a solution of
nitrate of mercury at a minimum of oxidation is added to it.
Lime water, or barytes water, is generally considered as Acetate of lead
the most sensible test of carbonic acid, I have found, that oe ae
the acetate of lead surpasses both. I was led accidentally acit.
to make this observation. Some distilled water, which I
kept in a cellar not very deep under ground, where how-
ever there were no fermented liquors, was rendered very
sensibly turbid, by adding this solution. Kirwan has ac-
cused the acetite of lead of being a deceitful test, his solu-
tion, which had been kept a little time, being sometimes
rendered turbid by pure distilled water. But it is not de= Net deceitful.
ceitful; the water in this case is not pure, it contains a lit-
tie carbonic acid. I prepared some distilled water free from
all carbonic acid. It was not rendered turbid either by
dimewater, or by the solution of acetite of lead. I passed
into ita few bubbles of carbonic acid, which acidulated the
water so slightly, that it neither reddened litmus paper, nor
rendered limewater turbid; but the solution of acetite of
dead whitened it perceptibly.
Acetate of lead is much less sensible to other acids. A Not so sensible.
solution of sulphuric acid at 1°85, diluted with 16000 parts TOUT Bei
of water, which acts sensibly on litmus paper, is not ren-
dered turbid by acetate of lead. Barytes water however
You. XVII.—Surrprementr. 2B detects
362
Mild nitrate of
Mercury a test
of phosphorie
acid.
Inquiry into the
formation of
miuriatic acid by
galvanism,
Apparatus.
NITRIC ACID AND AMMONIA FORMED BY GALVANISM,
detects -g3c5 of its weight in water acidulated with sulphu
ric acid, and surpasses in sensibility fe for this aeid all other
reagents.
The mild nitrate of mercury is almost as sensible a test of
the phosphoric as of the muriatic acid ; with this difference,
that the precipitate with the former is soluble in an excess
of phosphorie or nitric acid, but that with the latter is ab-
solutely insoluble in an excess of any acid whatever.
Xi.
Some farther Remarks on the pretended Formation of
Muriatic Acid in Water by the Influence of the Galvanic
Pile: by Professor Prarr, of Kiel. |
I HAVE continued my researches into the pretended for-
mation of muriatic acid in water, by the influence of the
positive pole of Volta’s pile. I have employed. glass tubes
of various diameters, from one line to an inch, The tubes
were closed at bottom, into which the’ conducting wires
were cemented with sealing wax. The communication be-
tween the two tubes, into one of which the influence ofthe
positive pile was conducted, while that of the negative com-
_maunicated with the other, was made at the top, sometimes
Wo traces of
Tnuriatic acid.
Some acid
hewever.
Probably nitric.
Ammonia too, '
~ Both from the
azote in the
water.
by wet paper, sometimes by linen threads, sometimes by
tendons, and sometimes by muscular fibre. I likewise va~
ried the metal of the wires, employing successively platina,
gold, silver, copper, and iron.
In all my experiments I could never obtain the least nig
of muriatic acid, though my test, the mild nitrate of mer-
cury, the most sensible of all for this acid, would have in-
dicated the presence of ¢¢gq5 of a grain. But I found by.
litmus paper indications of an acid; which certainly was
neither the muriatic, sulphuric, carbonic, nor phosphoric ;
since the nicest tests of these acids, which greatly exceed lit-
mus in sensibility, gave no signs of their presence. Inall pro-
bability therefore, it could be nothing. but the nitric acid.
I always obtained traces of an alkali too, which.from
every test was ammonia. J cannot therefore but adhere to
my opinion, that the acid and alkali are formed at the ex-
pense of the nitrogen adhering to the water ; which on one
side unites with oxigen, on the other with hidrogen.
XII.
~
N
PLASTER THRESHING FLOORS. 863
XII.
Description of the Mode of making Threshing-F lors in the
Commune of Valbonnais, in the Department of the Isére:
by Mr. J.J. Cuamvotzron Ficeac, Secretary to the
Society of Sciences and Arts at Grenoble, &c.*.
"Tue gypsum quarries eof Valbonnais furnish two sorts of 1° sorts of
plaster, one white, the other red. The white is found Be cea used
only in solitary strata, not very abundant: the red, which for floors.
is coloured by oxide of iron, is the most plentiful, and used
almost exclusively for threshing floors.
ed as fine as possible, and in this state left for ten days
’ before it is used. “It is to be observed, the more it is
For this purpose it is burned for 24 or 30 hours, pound- Calcined, pow-
dered, exposed
> to the air,
-burned, and the finer it is pounded, the better itis. Atwell mixed
‘the expiration of this term, and after the ground on which
with cold water.
the floor is to be formed has been made very level, the
, plaster is to be diluted with cold water in a bucket. It
must be carefully mixed so as not to have any lumps.
Two feet from one of the walls of the barn, and parallel A slip of wood
to it, a ruler is to be placedj of the height which the P!aced two feet
a Wed : from the wall,
plaster floor is /intended to:-have. This is commonly two and the plaster
inches-and half; or three inches. When the plaster is quite eH ae
smooth, has acquired a certain degree of consistency, and terval and
is inst beginning to dry, itis poured out on the space mothed.
between the wall and the rules. To level it another ruler
is passed over it, one end of which rests on the former,
the other touches the wall. It is then gone over with a
trowel, to make it as smooth as possible, every vacuity
is filled up, and any heterogeneous matters, that may be
‘on the surface, are removed. Thus a smooth level sur-
face is given to it, which is an essential quality.
As soon as this is done, a similar quantity of plaster This is repeated
prepared in the same manner is laid at the end of the for- — .
mer, and the same operations are repeated, till the plaster:
is extended to the opposite side of the barn, Here, how-ti!l within afew
inches of the
ever, it is absolutely necessary, to leave a little void Space, opposite wall.
\
af « Sonnini’s Bibliothéque Physico-économique, Feb. 1807, p. 315.
2B2 to
364
The board re-
moved two feet
farther, and
another layer
formed ;
and this repeat-
PLASTER TNHRESHING FLOORS.
to guard against the inconveniences that would ensue from
the plaster swelling when in contact with both walls. This
space may be three inches in a length of twenty feet.
Other layers of plaster are then formed in succession by
the side of this, bounding them always by the long ruler,
ed till the space placed at two feet distance from each preceding layer, which
js covered.
Every portion
must be well
united,
and ee whole
finished in a day +
if possible,
Ten days-after
the vacuity
Gilled up.
Will last 150
years,
and then may
be taken up,
burned afresh,
and laid down
again.
Will then last
as long as
before.
Quantity of
materials and
labour.
will keep them all of an equal thickness; and thus the
whole of the floor is completed.
Great care must be taken, that the successive portions
unite well together, that there may be no vacuity between
them. For this purpose it is necessary to finish the whole
in one day if possible: and to accomplish this a sufficient
number of men should be employed in diluting and pre-
paring the plaster, that those who are forming the floor:
may proceed without interruption. aie
Ten days afterward the vacuity left betweeu the floor
and the wall is filled up, and then it will be ready for use.
if in this time it acquire a deep red colour, it is a good
sign. Such a floor will last in common a hundred and fifty
years; and still longér, if it be not exposed to damp.
When its surface becomes injured by time, and i is no longer
as smooth as it ought to be, all the plaster may be removed,
exposed to. the weather for a fortnight, burned again as if
it were fresh taken from the quarry, pounded, mixed with
water, and relaid in the same place, proceeding exactly in
the same manner as when it was laid down the first time.
The floor thus remade will last as long as it did before.
The advantages of such a floor may readily be conceived,
when the high price to which timber has risen of late years is
considered. That some calculation of its cost ‘may ke.
formed, a square fathom of this floor, three inches thick,
will require about eleven hundred weight of gypsum ; and
two men can work up seven times this quantity in a day.
SCIENTIFIC
4
t
SCIENTIFIC NEWS. 369
SCIENTIFIC NEWS.
French National Institute *.
Mar. LAPLACE has investigated the phenomena of ca Laplace on ca-
pilary attraction; but instead of copying what Mr. De- pe ark at
Jambre says on this subject, we shall refer our readers to
p- 164, 169, and 286 of the present volume for what has
been. done by this celebrated mathematician; and to our.
next number for some remarks on it by a Icarned corres
pondent..
_In 1784 Mr. Roswag of Strasbourg Le ae to the Wire gauze
board of trade some gauze made of iron wire, for which he
received a reward; and the loom he invented for making it
“was lodged in the collection of machines of Vaucanson. In coated with
1799 Mr. Rochon made others, and coated them with a CTA Yo ain
transparent glue, to be substituted instead of horn for ship in ship lanterns.
Janterns to be used between decks, and in engagements by ee aula
night. He has since conceived, that with a thin coating of
plaster they might be employed to preserye ships from fire,
and buildings on shore still more easily ; or at least that they
would render the rayages of fire less frequent, and less ter-
rible. These gauzes might be very useful too for theatrical Safe stage des
decorations, which would not be liable to take fire. Their ©°U°"s-
only inconvenience is their being so little flexible; but Mr.
Rochon does not despair of means being found by chemistry
to remedy this imperfection, and it was with a view of call-
ing attention to this subject, that he read a paper on it to
the class.
| An eclipse of the sun is among the most useful pheno- Total eclipse of
mena for the verification of astronomical tables, or for the the sun..
determination of the longitudes of places. It is likewise
on of those, that most attract the attention of observers.
Mr. Lalande, true to the custom he has followed these fifty. \
years, has calculated all the observations he could collect of
the eclipse of 1806. Cloudsconcealed it from the astrono-
* Abridged from the account of the proceedings of the mathe-
matical division of the class of mathematical and physical sciences
given by the perpetual secretary, Mr. Delambre. ae ee
2 . sais mers
366 SCIENTIFIC NEWS.
§
mers of Paris: but it was seen in several parts’ of Franee,
Observedin Germany, Holland, and Italy. In America it would be
America: ; P - 5 29
particularly interesting, as at Boston and Albany it was to-
tal. At Kinderhook, near Albany, it was observed by
Mr. Ferrer with excellent instruments. He eoncluded ‘the
conjunction to be at 45 min. 33 sec. after 11. Mr. Lalande
found precisely the same: and as he learned by other obser-
vations, that it happened at 30 min. 6 sec. after 4 at Paris,
it follows, that the difference of longitude of these two
places must be 7h. 15’ 27” of time.
~ The eclipse was observed at Albany too, but at’ the in-
stant of the return of the light the observer had not his eye
at the glass: and though this phenomenon would appear to
be of a nature to be seen as accurately with the naked eye,
it seems to have been noticed a few seconds too late.
‘Disk ‘of the A curious remark of Mr. Ferrer is, that the disk of*the
moon illumined
from its atmos- Mon appeared illumined a few seconds before the end of
phere. the total eclipse, which seemed to him an effect of ek at.
mosphere of the moon.
‘Only six stars The darkness was’ not so great as was expected. Bit
hia agg ny six of the principal stars or planets were seen. “A luminous
ded by a lumi- ring of 45 or 50’, surrounding the sun, diminished the oP:
mous ring. scurity.
Irradiation of From the comparison of this total eclipse with some an-
sao ala opnular eclipses observed before, Mr. Lalande thinks, that
the moon 2” the irradiation of the sun is 2”; and that 1’ must be added
pata Kwesay to the semidiameter which he had assigned to the moon from
culated. direct observations made at the full.
The sun move Many astronomers have supposed, that the sun is not im-
able inspacey movable in space. Mr. Lalande conjectured from its ro-
tatory motion, which is unquestionable, that it has a move-
ment of revolution. What he suspected Herschel has en-
deavoured to prove by observations. Mr. Prévot, of the
academy of Petersburg, has been led to the same result:
but Mr. du Séjour, having treated the question analytically,
has found, that it is insolvable when considered in its to-
tality. The results to which Mr. Herschel has been led by
the ogee motions of different stars * do not accord suf.
¥ See our Toute, vol, XHI, p. 50, and XV, p. 232, and 269.
ciently
ee ee ee ee ee ey
SCIENTIFIC NEWS. i 367
ciently to establish the motion of the sun, and immobility and the stars
likewise : so
of: the stars: it rather appears, . that they are allhin motion $41.5 sts motion
and it is on this supposition, that Mr. du Séjour declares the:cannot be de-
problem insolvable. a
_ Notwithstanding this decision, Mr. Bacal has~sub--Burckhardt has
jected it to\analysis anew. His formule are more commo- bane pea
dious, and more easy of application, than that of Mr, du
Séjour ;. and are less Jaborious than the trigonometrical cal.
culation of Mr. Herschel. He has very adroitly eliminated
the distances of the stars, which appear to be, and really
are, one of the elements of the calculation, and which will
‘probably remain for ever unknown tous. If the sun alone ff
be in motion,. this motion may be known to a certain degree
of.accuracy, in time, by means of good observations: but
if the stars too move, the separation of the unknown quan-
tities will, be impossible, and some embarrassment will en-
sue to.future astronomers, should there be an interruption
to observations for a few centuries; and should they at-
tempt to calculate the celestial movements anew by compar-
ing their observations with ours, after a period of ignorance
of some duration. But even on this supposition, which is
fortunately very improbable, it would only follow, that the
observations of the 18th century would appear a little less
accurate; which would not prevent them from furnishing .
much better helps, than we found in the small number of
rude observations transmitted to us by the Grecks.
_ The problem of finding the train of wheels necessary to Problem of
aauicant the motions abe the planets was resolyed by Huy- aes oe
-ghens in a very complete manner by continual fractions, planetarium.
-which haye the advantage of furnishing approximate values,
expressed by the smallest numbers possible, in every degree
of approximation with which the artist may think proper
to content himself.. But to this every artist who attempts
to construct a planetarium isnot equal. Mr. Burckhardt
_therefore has pointed out to them calculations more easy,
and sufficiently exact. é
To these labours of the class may be added the reports Pyreolophorus,
made by its committees on the most curious and important
“inventions submitted to its judgment. On both these ac-
counts we shall particularly mention the report-of Carnot
Yes: \' on
368 SCIENTIFIC NEWS.
on the machine invented by Messrs. Nieps, and called by
them a pyreolophorus. By this word, compounded from
mve, fire, ‘oiode:, wind, and «, to carry, the inventors —
intended to point out the moving powers of the machine,
which are wind from a pair of bellows, and air suddenly
A power equal €xpanded by fire*. Their object was to discover a physical
tothe steam power equal to that of the steam engine sesgaters: same
engine with less
consumption of 80 much fuel.
sane age To form an idea of the manner in which thing produce
S mode OF ac~
tion, and call into action the sudden expansion of air, suppose a
copper receiver to be firmly fixed to a horizontal table. To =
one of its sides is fitted a tube, by means of which a body
of air is conveyed into the receiver. This air meets in its
way afew grains of combustible matter, which it projects — -
on a flame, where it enters into ignition. The inflamed
matter, entering into the receiver, expands its contained air
: with great force, which is exerted against the sides, and
pushes forward a piston, sliding in a second tube, fitted to
one of the sides. This piston drives before it a column of
water, or any other body exposed toits action; after-which
the piston returns of itself to its former place, and the ma.
chine, ‘recovering its former state, is again ready to act as
before. All these effects take place in five seconds of time.
Esperiments Ina trial made by the inventors, a barge loaded with nine.
with it. hundred weight, and its bow presenting a resistance of ‘six
square feet to the water, aseended the Sadne with a velocity
double that of the stream. In another trial made by the
_ committee, the ‘pressnre exerted on a piston of 3 ‘inches
** -square was equal toa weight of 57000 grammes (126lbs)5;
the interior capacity was 21 cubic inchess and the con,
sumption of fuel was only 0:32 of a gramme (5 grains).
The inventors mean to carry their first attempts nearer to
‘perfection: but even im the présent state of the machine,
its violent concussions, the shocks it gives to what stipports
it, and the celerity of its motions, leave no doubt of the in-
* ‘This principle has already been employed in our own country,
and. we understand its powers were found to be very great; but
| some ‘obstacles occurred, that prevented it from being followed up.
‘From the account given by Messts. Nieps, however, it was not pre
cisely i in thé same way as their contrivance, but’on a simple and
More scientific principle. W.N.
tensity
SCTENTIFIC NEWS; 369
tensity and impetuosity of this new moving principle; and
vajuable results may be expected from it, >when by repeated
trials all the energy of which it is susceptible is imparted to
it. Such is the opinion of the committee, and the class de-
termined, that the whole of their report should be inserted
in the historical part of its memoirs, to preserve the remem.~
brance and date of the first trial of an invention that may
prove highly important. = vie
Mr. Pictet presented ten models of scapements from New scape~
Messrs. Malley of Geneva, three of which belonged in part Zien:
to Mr. Tavan, the artist who made them all. They dis-
played an inventive genius, and great merit in the execution.
Mr. Desmarets read an ‘interesting report on a new ma» Frame for
chine for weaving ribbed stockings, invented by Mr. Bel- wg,
Jemére: ‘This is not above half as expensive as the English
stocking-frame, and its movements are much lighter. Its
advantages are confirmed by two years experience.
From the learned researches of Mr. Coulomb, and the Variation and
formule of de Borda and Laplace, we are now able to de- Se, aut east f
termine with sufficient precision, and without too many dif- netic power.
ficulties, the variation and dip of theneedle, and the inten-
sity of the magnetic forces. But these nice observations
require perfect instruments, time, and an exact knowledge
of the meridian -of the place. The observations which na-
vigators, to whom most of these are often wanting, have
been able to make, are not to be depended upon sufficiently
for us to infer from them with certainty the situation of the
magnetic poles and equator,.and the pomts where the mag-
metic equator intersects that of the earth. Mr. Biot how- Mr Biot has at-
ever has attempted to determine, from the observations of ‘Pid t0 as_
certain the ele-
Ja Peyrouse and von Hamboldt, all these elements of the ments of the
magnetic theory of the globe; and ‘he has given the neces. Ge ee ot
sary formule for calculating what the variation and dip of
theneedle should be in any given place.
“The journey which Messrs. von Humboldt and (Gay- Humboldt and
Lussac have since made in Italy, France, and Germany, coy Les
has afforded them repeated opportunities of comparing their many observa-
me te seh eee ee Peps . +m tions.on the dip
observations with the hypothesis of Mr. Biot. The diffi- 57 4.0 nbelie
culty of ascertaining the meridian prevented them from ob- and the mag-
serving the variation of theneedle at their different stations ; Pn of
but
3710
These did not
coincide with
Biot’s hy pothe-
sis,
The dips were
all im excess,
SCIENTIFIC NEWS.
but they observed the dip, and the number. of oscillations
‘made in a given: time by a horizontal needle, whence by a
very simple formula they deduced the number of oscillations
‘it -would have made in its truedirection, and the intensity of
the magnetic forces.
To exhibit the whole of their labour at one view, and the
consequences deducible from it, Mr. Gay-Lussac has given
a general table of the observations themselves, the geogra-
phical latitude and longitude of the place, the latitudes and
longitudes referred to the magnetic, equator according to the
hypothesis of Mr. Biot, the dips calculated according te
this hypothesis, and the differences they found between their
observations and this calculation. To this he has added ob.
servations on the nature of the soil, and its elevation above
the level of the sea.
It is to be remarked, that all these differences are in the
same direction, the dips by calculation being from 3° 42"
“to 5° 9’ too great. Admitting, that some of these differ-
ences may be ascribed to local circumstances, or the un-
avoidable errours of observation, it appears at least highly
probable, that a more considerable part arises from the. si-
tuation attributed to the nodes of the magnetic equator, and
to the angle it makes with that of the earth. It will not be
difficult to determine the corrections, that Mr. Biot’s hy-
pothesis requires, to agree much better with these new ob-
servations, ‘and reconcile them with those from which he
determined his first elements. It is to be presumed, that.
Meridian line
Mr. Biot himself will consider this as an object of sufficient
importance to engage his attention, when he has finished the
important and difficult undertaking, on which he is now
employed *. To give this theory all the precision of. which
it is susceptible, it is much to be wished, that we had a se-
ries of observations made in remoter parts of the globe with
the same care as those of von Humboldt and Gay-Lussac: |
but-in the mean time we perceive, that the intensity of the
* Messrs. Biot and Arago set. off in September last to continue
, extended to the the meridian Jine to the Balearic islands, and finish the Jabours
" Balearic is-
jands.
interrupted by the death of Mr. Mechain. In December they be-
gan the observation of the great triangle, which is to connect the
island of Ivica ‘with the coast of Valencia. nt berlen
magnetic
SCIENTIFIC NEWS. 37r
magnetic forces increases with the latitude, as Mr. von Hum-'The magnetic
boldt had already remarked on his American tour; for ela tein
Berlin it is 13703; while at Rome itis only 12642. It fol-‘tude.
lows too from their labours, that thé influence of ‘the chain tai tae
of the Alps was very fecble, if any thing. That of Vesu- tle or nothing.
vius at the moment of the earthquake and eruption of 1805 a nay
was not much more perceptible, and this would appear to eruption the
be owing rather to local circumstances, than to a particular #™°
magnetic centre.
“The description of the instruments employed in these ob-
servations, and the disquisitions entered into by Mr. Gay.
Lussac respecting the’ best means of making them, cannot
fail to add to the confidence, which thé well-known accu-
racy and skill of the observers must naturally inspire.
From eudiometrvical experiments, and the analysis of the All gases sup.
air, Messrs. von Humboldt and Gay-Lussac had been led — ciecoomeg
t6 suspect, that all gases might have the same capacity for the same capa-
caloric. This consequence, which appeared deducible from “'Y fr heat ;
their observations, deserved a more scrupulous examination,
which Mr, Gay-Lussac undertook on his return. His new
experiments confirmed those before made, yet led him to an
opposite conclusion. The gases he had observed with Mr. but this is true
yon Humboldt had in reality nearly equal capacities for heat, peo ead
_ but it was wrong to ascribe the same property to all gases
without distinction.
The apparatus contrived by Mr. Gay-Lussac’ was ~ex- Gay-Lussac’s
tremely simple. It consists of two equal globes, each with Fa
two tubulures, one fitted with a cock, the other with a very this.
sensible spirit thermometer. The globes having been freed
from moisture by dried muriate of lime, they were exhaust-
ed of air, and one was filled with the gas to be tried. “The
communication between the two balloons being then opened,
part of the gas included in the first rushed’ into the second,
till an equilibrium was established; and then Mr. Gay-~
Lussac carefully examined the changes of temperature indi-
cated by the two thermometers. .
In the first experiment, the subject of which was atmos- Air rushing in-
pheric air, he saw with astonishment the thermometer rising eee 4
perceptibly in the exhausted globe in proportion as the air '
yushed into it. This fact appears diametrically opposite to
kas another
372 SCIENTIFIC NEWS. ;
another well known, which is, that a volume of air inclu.
ded in the receiver of an air-pump continually absorbs ca-
Joric as it dilates under the rising piston. It may be said,
that the vacuum in the second globe was not sufficiently per-
fect, and that the air remaining in it, being compressed by
the saiaitionel quantity admitted, was obliged to give out
part of the air it contained: but this explanation Mr. Gay-
Lussac refutes, first by reasoning, and afterward by a. di-
rect experiment.
and this inpro- If the alcohol ascend in the second thermometer, it de-
ae ap its scends nearly the same quantity in the first. Now if, after
having exhausted the second globe, the communication be-
tween them be opened, the gas, equally distributed, will be
reduced to half the density it had before; and one of the
thermometers will be seen to rise, and the other fall, each
in an equal degree, but less than before, in consequence of
the diminution of density. And if, by repeating the ex.
haustion, the density be reduced to half what it was in the
second trial, and consequently to ¢ what it was in its origi-
nal state, we shall find the equal and opposite variations. of
the two thermometers still following the ratio of the density.
Othergases, Similar experiments, made with particular attention, on hi-
Prognag AN drogen, oxigen, and carbonic acid gas, produced similar |
mena, results; that is to say, the quantities of caloric absorbed
in the first globe, and evolved in the second, were always
equal to each other, and proportional to the density.
Contrivance for. "To render the experiments comparable with each other,
si esint ate it was necessary, that the time occupied by all the different
mission of the gases in their transmission from one-globe to the other should
Sas. be the same. This Mr. Gay-Lussac effected by a contriv-
ance equally simple and ingenious, which diminished the ori-
fice of the connecting tube in the ratio of the square_ root
of the densities: and thus the time of transmission for all
‘the gases was found to be cleven seconds.
Of these experiments, which deserve the attention of the
natural philosopher, and which Mr. Gay-Lussac purposes
to verify and extend by farther observations, the following
are the results, which however he offers with some diffidence.
General results . 1. When a vacuum comes to be occupied bya gas, the
seas exper caloric evolved is not owing to the little air that might be
left_in it. és
2. If
SCIENTIFIC NEWS, 378
\
9. If a communication be opened between two equal
spaces, one a vacuum, the other filled with a gas, the vari-
ations of temperature, positive in one and negative in the
other, are equal in quantity, but not in intensity.
3. In the same gas these variations are proportional to the
ehange of density it undergoes.
4. The variations in different gases are so much greater,
_ in proportion as their specific gravities are less. ’
_. 5. The capacity of a gas for caloric in a given volume di-
minishes with the density.
6. The capacities of gases for caloric, in equal volumes,
are so much greater, as their specific gravities are less. This
consequence will be evident to those who know the experi-
ments, by which Mr. Gay-Lussac had already proved, that
all gases are equally affected by equal elevations of temper-
ature.
_ Mr. Cotte, correspondent of the Institute, has compared Progress of
the progress of several thermometers, both of mercury and oe,
alcohol, in various expositions, during the hottest days of mercurial and
the three memorable summers of 1802, 1803, and 1806. *P'"%
Two of these thermometers, one mercurial the other in doors and
spirit, were placed out of doors in the shade, and facing the VEL sum
north; two others were exposed to the direct rays of the shade.
sun; and two were within doors. All of them were con-
structed with the greatest care, and under the inspection of
different members of the Academy of Sciences. Before
Mr. Cotte examined the effects of different exposures, he
determined, by taking the mean of a great number of ob-
servations, the comparative motions of these thermometers
in the same situation.
It follows from these experiments, that the differences be- Differences be-
tween the mercurial and spirit thermometers are much more pages Soi)
considerable, when they are exposed directly to the rays of est in the sun.
the sun; which Mr. Cotte ascribes chiefly to the red. colour
of the spirit: and this difference is greater, the greater the
‘heat. :
_ The greatest hourly variation takes place from 6 to 7, Hourly varia-
: . . ° . ° tions. ‘
and more especially from 7 to 8 in the morning; it continues
diminishing till 11; thence it increases till 2; and between
_ 2 and 3 it diminishes a little.
” ‘The
STA ; SCIENTIFIC NEWS.
The difference, between the mercurial and)spirit thermos
weters exposed to the sun is nearly the same from 10 sin the
morning till 4 in the afternoon. :
The greatest Lhe maximum of the thermometers within diiaus esc at
heat without happen on the same days as that of the thenm objeters with.
doors not al- j
wayson the out.
ine Cas as &- cloud passing rapidly over the sun suddenly sinks the
| Clouds affect Spirit 2° or 3°,.the mercury about 1° only. When the
Spint most. —_cloud has passed, the liquid rises as quickly. beau:
passe most ‘The motion of the mercury is most uniform.
Time of great- The maximum of the thermometers out of doors in the
est heat. shade takes place from 2 to 3: that of the thermometers in
the sun, from 3 to 4: and that of the thermometers within
doors, from 6 to 7, in the afternoon.
ribet essa ob- | When the heat is. the greatest, a kind of Waenien oud
erved.
spirit, which causes them to rise-aud fall continually.
Relation be- Mr. Carnot has published a memoir on the Relation that
cae has se exists between the distances of any five points taken in space,
five points in followed by an-essay on the Theory of Transversals. This
ae by Car forms an interesting appendage to the Geometry. of Position
of the same author. In it-will be found a number of use-
ful or at least very curious theorems; analytical formule
for resolving all the problems respecting a quadrangular py-
’ xamid, without supposing any knowledge but that of its
edges. All these formule are symmetrical, and possess a
degree of ‘elegance, that will much please the geometrician.
Some, itis true, may stagger the hardiest calculator, and
much shorter solutions might be obtained by the skilful ap-
plication of trigonometry ; but each problem would require
new considerations, which do not immediately present them-
selves to the mind, while here every thing flows in the clear.
est manner from a few known principles...This work there. .
fore is a repository; whence the geometrician may derive
expressions, (that will facilitate the solution of very compli-
catedsproblems.. 'To-give an idea of the calculations) of the
author, we shall quote: the enunciation of one of the last
problems, which is as it were the summary of those that
precede: ‘* Of ten right lines, joining any five points | taken
in space two by two, nine being given to find the tenth.”
agitation is observed in the mercury, and still more in the
ss ‘
j
SCIENTIFIC NEWS. 875
The Essay on Transversals is not less curious. The fun- Camot’s Essay
damental principle of this likewise may be found in the Geo- Ea Ma ac
metry of Position; and it was one of the two, on which _
Ptolemy built all his spherical trigonometry. The word
transversal is here employed to signify any right line, cut-
ting the three sides of a right-lined triangle or their prolon-
gations. An equation of remarkable simplicity expresses
the ratio between the segments of ‘the sides. Mr. Carnot .
immediately deduces from it three other formule of the same
nature, which, transferred afterward to spherical trigono-
metry, are found to be the same as Ptolemy had deemed suf-
ficient for the purposes of astronomy: He demonstrated
them synthetically, according to the method of the ancients;
and his demonstrations, enlarged by his commentator Theon,
are not very complex. Mr. Carnot, after having demon-,
strated the first principle exactly im the same manner as Pto-
lemy, finds in our modern trigonometry more simple means
for the others. i
After having coincided with the Greek mathematician, he
extends thetheory in various ways, applying it to plane and i
spherical quadrangular figures; to every polygon, plane or
even oblique; and lastly to pyramids: applications that are
perfectly new, and of which not the least trace is to be
found either in Ptolemy, or in his commentator.
Mr. Lacroix has published a fifth edition of his Elements 5th edition of
of Geometry. ae i
Mr. Haiiy has published a second of his Elements of Na- Lacroix,
tural Philosophy. The great and rapid success of the firs it tuys Ble -
edition renders it unnecessary for us to enter particularly ments of Natuc
into the plan and exetution of a work, which its author has ™! Philosophy,
revised throughout, to enrich it with all the new discoveries,
that have taken place in such a short interval. Thus we
find in it Mr. Laplace’s theory of capillary phenomena;
Mr. Gay-Lussac’s experiments on the dilatation of gases;
-and the researches of Mr. Biot into the relation between the
‘refractive power of different substances and their chemical
composition, which he has just finished. _
= Lectures
376 SCIENTIFIC NEWS.
Lectures at St. Thomas’s and Guy’s Hospitals.
Medical and
surgical 104 Tre autumnal course of lectures at these hospitals, will
tures. ~ commence as follows: :
: S¢. Thomas’s.
Anatomy and the operations of surgery, by Mr. Cline
and Mr. Astley Cooper, Thursday, Oct. Ist, at 2 ’clock.
Principles and practice of surgery, by Mr. Astley Cooper,
Monday, October 5th, at $ in the evening.
Guy’ s.
Practice of medicine, by Dr. Babington and Dr. Came
Friday, October 2, at 10.0’clock,
Chemistry by Dr. Babington, Dr. Marcet, and Mr. Allen,
Saturday, October 3, at 10 o’clock.
Midwifery and Si is. peculiar to women and children,
_ by Dr. Baighton, Monday, Oct. 5, at 8 in the morning.
Pathology, therapeutics, and celrene medica, by Dr,
Curry, afd Dr. Cholmeley, Tuesday, October 6, at $ in
the evening.
Physiology, or laws of the animal Gicononiy, by Dr.
Iaighton, Wednesday, October 7, at 7 in the evening,
Experimental Philosophy, by Mr. Allen, to begin in
November.
Clinical Lectures on select medical cases, by Dr. Babings —
ton, Dr. Curry, and Dr. Marcet.
N. B.. The several lectures are so arranged as not to in»
terfere with each other in the hours of attendance; and the
whole is calculated to forma complete course of medical :
and surgical instruction. - Terms and other particulars to
be learnt from Mr. Stocker, apothecary to Guy’s Hospital,
who is also.empowered to enter gentlemen as pupils to such :
of the lectures as are delivered at Guy’s. :
— es ee.
Fourcroy’s Phi» “A. F. Fourcroy, professor of chemistry at Paris, has
losophy of Che- ) ptishedan enlarged edition of his “¢ Philosophy of Che. |
muistry.
mistry,’’ which is considered as. the best elementary work
on that science. <A translation of it by Mr. W. Desmond,
is in the press, and may be expected early in September.
INDEX.
INDEX.
ze A A.
Acetic zther, preparation of, 219
Acid, sulphuric, fabrication of, 41—
gallic, facts towards a history of, 58
—sulphurous, 303 f
Acoustics, experiments in, 211’
Adhesion of bodies to the surface of
fluids, 169
ZEtheogamia of Palisot de Beauvois,
- 807
#B ther, acetic, see Acetic ether.
Affinities of substances to fluids, 286
Alegar, premium for the improvement _
of, 232
Alge, 309
Ambergris, on, 340
Anfrye, M. his analysis of ancient ‘pew-
ter, 311
Animal resistance to the effects of heat,
144, 216
Arran, Isle of, mineralogical and geo-
logical observations in, 344
Artillery, improved matches fer, 31
Astringents, action of, upon solutions
of iron, 58
Attraction and repulsion of small bodies
floating on the surface of liquids,
164
Austin, Mr. J. account of his new ©
weaving loom worked by steam and
water, 175
Autographs from stone blocks 231.
Auzilly, M. 10.
B. -
Baduel, M. 227
Banks, Sir Joseph, his experiments on
the influence of a high temperature
of the atmosphere on the animal
é€conomy, 145 —
Vor. XVII.
Baraillon, M. on ancient pewfer, 311
Bartholdi’s process for obtaining pure
gallic acid, 59, 60, 62
Beauvais’s system of the fructification
of mosses and mushrooms, 307—
His insects collected in Africa and
America, 310
Berger, M. 215
Bergman on cast iron, 187
Berthollet, M. his researches into the
nature and properties of the gallic
acid, 58, 61.--On prussiate of pot-
~ ash, 89, 92, 109.—-On capillary at-
traction, 174.——On cast iron, 187,
189.—On the degrees of oxigenation
indicated by the colour of precipitates,
268.—-On sulphurous acid, 303
Berthollet and Guyton on the fabrica-
tion of sulphuric acid, 45
Bigger, Mr. Walter, 178
Billardiere’s, ‘‘ Flora of New Holland,”
289 4
Binocular telescope, 201
Blagden, Sir Charles, on atmospheres
of high temperature, 145, 215
Blasting rocks, by means of sand,
227
Blende, on, 337
Boerhaave’s theory of respiration, 143
_ Boiler, a newly-constructed one, for.
saving fuel, 5.—Improvement in,
312
_ Bonpland, M. 309
Bookbinders’ cutting-press, improved, »
336 =
Borda, M. his proposed matches for
artillery, 32
Bosc, M. 307
Bouche, M. his experiment of the.
application of the powers of elec-
tricity to discharge cannon, 232
b Brissony
INDEX.
Brisson, Mr. his “* Treatise on Specific
Gravity,” 191 hi
Bucholz, M. on the conversion of chalk
by fusion into a substance analogous
to marble, 220—On the red iron-
stone of Suhl, 230—On the volcanic
calcedony, 230
Bugs, method of destroying, 58
Buifon, 212 Rs
Ci
Caddel, W, Esq. 5
Cadet, C. L. on wooden matches. for
Artillery, to be used instead of 1ope-
match or port-fires, 31—Elis ana-
lysis of coffee, 113 _ >
Calcedony, volcanic, 250 —
Camera Lucida, 1, 312
Candolle, M. 227—On parasitic fun-
guses, 308
Capillary attraction, 170, 286, 265
Carradori, Dr. 275
Cartheuser, M. on the gallic acid, 58
Cast iron, 185 »
Cement to keep out wet from walls or
floors, and for joining stone or
marble, 142
Chalk converted into a substance analo;
gous to marble, 22 iy
Champagne, vines and winas-of, 353
Changeux, M. on the resistance of the
human body to the effects of heat,
146 bag
Chaptal, M. 183—Questions by, respect-
ipg the vines and wines of Cham-
pagne, 353
Chenevix, M. on coffee, 121, 127—__
On the fusion of metals, 183
Chevreuii, M. 46
Cheselden, 213
Clark, Mr. J. on the use of gall in paint-
ing in water-colours, 341
Clement, M. see Desormes and Clement.
Cobalt, facts towards a history of, 46
Cochineal, on, 540
Coffee, extract from a dissertation en,
143 ;
Cold, effects of on the animal systems
142 ,
Colours, experiments on, 18—-Com-
binations of, and the results pro-
duced therefrom by refraction, 204.
—Ditto by reflection, 206
Condillac, 212
Condor, the, described, 310
Copies of written paper obtained by
pressure, 178
Copying machine, 178
Corbet, Mr. Archdeacon, 74
Cotton dyeing and printing, 184
Crawford, Dr. on the effects of heat on
the animal constitution, 147
Cross, Mr. Hugh, 178
Curaudeau, on Prussiates, 109 -
Curyilinear saw, 334
Curwen, Mr. Account of his drill horse-
hoe, or weed-harrow, 281
Cuthbertson, Mr. communication from,
on the electricity of saline bodies, 12
Cutting-press for Bookbinders, impro-
ved, 336 :
Cuvier, M. his inquiries concerning ani-
mals known to the ancients, 510
D.
Dalton, Mr. on the absorption of gases-
by water, 275
Damp wells, method of curing, 141
Darso, M. on the oxidations of iron,
221, 267, 328 ;
Decomposition of Light, 18
Delametherie, J. C. 229
Delaroche, F. ¥. his experiments on
the efiects produced by a high tem-
perature on the animal economy,
142, 215
Delaville, Dr. on the oxidation of lead,
207
Delineation, new instrument. for, 1,. 512
Descotils aud Hassenfratz’s examination
of sparry iron-ores, 311,
Desormes and Clement on the fabri»
cation of sulphuric acid, 41
Deyeux, M. bis sublimauon of the gallic
acid, 58, 60
Dobson,
=
Np ES.
Bobson, Dr. on atmospheres of high
temperature, 146
Drill horse-hoe for turnips, or weed-
harrow, 281, 284
Drummond, Mr. John, 178
Duhamel, see Tillet.
-Duntze, Arnold, his experiments on
animals, to ascertain the degree of
heat they were capable of bearing,
144
Dupont, M. de Nemours, on instinct,
299
Durosier, M. on the preparation of ace-
tic zther, 220
Dyes, violet purple, 132
Dykes, Mr. J. D. B. 283
Eclipse of the sun, total, observed in
America, 365
Fel, electrical, of Surinam, 310
Electrical experiments, 11
Electricity, application of its _powers to
discharge cannon, 232
Ellis, Mr. H. his relation of a remark-
able fact respecting heat, 143
Emeritus on looming or horizontal re-
fraction, 153
‘Erman, M. his memoir on two new
classes of galvanic conductors, 2323,
316 :
Estremadura, silver mines of, 129
@
“GE.
Faro Islafids, charts and description of,
lately published, 221
Fernandez on the solution of muriate of
silver, 188 ts
Field, Mr. G. account of his stove for
heating rooms, or drying different
articles, 263
Figeac, Mr. J. J. C. his description of
the mode of making threshing-floors —
™ in the commune of Valbonnais, 363
Filtering stones, 190
Fir-trees, remarks on pruning, 157
Flint, sculptured, a curious autique,
195
pect “ Greraty Sica:
|
Fordyce,
Flint of recent formation, 230
Dy. his experintents on animal
heat, compared with that of the’ at-
mosphere, 145, 215 "
: Fossils penetrable by water, 193
Fossil remains of lost animals, -310-*%
Foster, Mr. Matthew, 285 = °° ‘
Fourcroy on gallic acid, 69—-On the
_ degrees of oxigenation, 268 .
Franklin, Dr. on the effects of heat on
animals, 144
Fuel, economy in, derived from a newly
constructed boiler, 5, 312
Funguses, 308 -
; G.
Gaff, Thos. Esq. 283
Gall, on, 540 }
Gallic acid, facts toward a wea of,
58
Galvanism, 149, 233, 316,362 |"
Gases supposed to have an equal capa
city for heat, 371
Gay-Lussac, on the absorption of og he
by water, 275 /
Ge hlen, M. on the preparation of ace-~
tic ether, 219——See 229
Geometry, Elements of, by Lacroix, 375
Gerhard, on fossils penetrable by water,
193
Germon, M. on the manag>ment of
yines and wines in Champagne, 353
Gillet-Laumont, Mr.—See Laumont.
Gioanetti, M. on the action of astrin-
gents.on solutions of iron, 58
Grignon’s refined cast iron, 186
Growth of trees in the Botanic Garden
at Calcutta, 110 4 jl
Guadalcanal, platina found in the cies
mines of, 128
Guyton de Morveau, M. his experi-
ments on the adhesion of bodies in
fluids, 172—On filtering stones, and
the method of determining the specific
gravity of substances with large pores,:
190-—His report on a sculptured head.
of flint, 195—_-See Berthollet and
Guyton.
_ Gy, M. And. de, on the structure of
b v; Mount
outbstirnces euch
Cags Jreres —
INDEX
Prussiates, facts towards a history of,
89, 249 —
Pumice-stone, analysis of, 194
Pyreolophorus, 367
R.
Reagents for muriatic, carbonic, and
sulphuric acids, and for ammonia, 360
Redowski, Mr. his projected scientific
expedition, 232
Refraction, horizontal, 153
Reid, Mr, James, 178
Repulsion, see Attraction.
Respiration, 143
Reuter, Mr. his invention of printing
from autographs of stone, 231
Richter’s. process for extracting and
purifying» gallic acid: compared with
the inventions of other chemists,
58, 60, 7k Gull $ 2 hes |e
Ritter, M. on muriatic acid and soda
formed by galyanism, 231
Rockets discharged by means of elec-
«. tricity, 232
Rocks, method of blasting with sand,
adopted in France, 227
Roxburgh, Dr. his table of the growth
of trees in the Botanic Garden at
Calcutta, 110
_R.T. on the art of making copies of
written papers by pressure, 178
Rumford, Count, description of his
new boiler, constructed with a view
to the saving of fuel, 5—-His experi-
ment on the use of the heat of steam
in place of that of an open fire, m the
making of soap, 10.—His adherence
to the old theory of heat, 311
) s.
Saline bodies, their habitudes with. re-
gard to electricity, 11
Salmon, Mr. R. on pruning fir-trees -
157 ;
Saussure, on the heterogeneous particles
contained in air, 279
-Saw, acurvilinear, 334
“Bay, M. 194
Scapements, new, for time-keepers, 369
Seheele’s discovery of the means. of
separating the gallic acid, 55, 71.—
On. prussiates, 106, 109, ,249—On
acetic zther, 219.—-His mistake re-
specting oxigenation, 274
Schul, J. H. Von, 104
Scientific News, for May, 88—June,
151—July, 227—August, 306, 365
Scientific voyage, 252
Sea-water, analysis of, 72
Segner, M. on capillary attraction, 174
Seguin, M. his method of freeing alum .
from iron, 511
Skrimshire, Mr. W. jun. on i ha
bitudes of saline bodies, with regard
to electricity, 12
Soap-boilingy improvement in, £9
Soehné, Mr. 183
Solar motion, 366
Solander, Dr. on the influence of ex-
treme heat on the animal con- - >
stitution, 145
Sound, experimentson, 211
Sphex, interesting economy of the,
302 ,
Steam, boiler for generating, 5—-Ex-
periment on the use of, in the ma-
’ nufacture of soap, 10
Stereqmeter, 194
Stove for heating and drying, 263.
Sulphuric acid, theory of the fabrica-
tion of, 41 j
Sulphurous acid, remarkable properties
of, 303
Swimming'Society in Denmark, 234
ee
Talaker, Mr. William, 189 ‘
Tatum, Mr. John, on the increase of
temperature produced by the galva-
nic actidn, 149
Telescope, Binocular, 201
Temperature, increase of by phen;
149
Tempest
INDEX.
Tempest on the 18th Feb. 1807, ob
servations on, 88, 151
Tenon’s ** Memoirs on the Dentition
of the Horse,” 510
‘Tests of certain acids and ammonia, 360
Thenard, M, his discovery of white
oxide of iron, 268
Thermometers, experiments on, 873
Threshing floors of plaster, 363
Thillaye-Platel, Anthony, on the car-
bonization of turf, a process by which
all possible advantage may be derived
from products hitherto neglected in
that operation, 131
Tillet and Duhamel, on the effects of
heat on animals, 144
Tilloch, Mr, A. letter from, on the im-
proved bookbinders’
336 ;
Torpidity of certain animals during the
winter season, prize questions relative
to, 306
Transversals, theory of, 574
‘Trees, table of the growth of, 110
Tremery, Mr. 25
Trituration of mercury, machine for,
313
Trotter, John, Esq. his curvilinear saw
described, 334
Turf, carbonization of, 131
cutting-press,
V.
Variation and dip of the magnetic
needle, £69
Vapour-baths of Russia, 143
Vauquelin, M. his account of the pla-
tina found in the silver-mines of Gua-
dalcanal, in Estremadura, 128—His
analysis of the iron-ores of France,
810 :
Vaux, M. Antony Alexis Cadet de, on
coffee, its history, properties, and the
mode of obtaining from it the most
pleasant, wholesome, and economical
verage, 113
-Ventenat’s. © Garden of Malmaison,”
809 .
Vines, culture of in France, 353
Violet purple dyes, 182
Vision, experiments on, 201
Von Schule, J. H. 184
W.
Wailly, M. 191
Waistell, Mr. C. account of his drill
horse-hoe for turnips, 284
Wallerius on the filtering-stone, 190
Wasp, ichneumon, interesting economy
of the, 302
Waste lands, improvement of, 74
Water of the sea; observations on the
soda, magnesia, and lime, contained
i thse
Waugh, Mr. John, 178
Weaving frame for ribbed stockings, 369
White oxide of jron, examination of,
268 ;
Wilson, Mr. Charles, his method cf
curing darep walls, by the application
of a newly-invented composition, 141
Wines of Champagne, management of,
553
Wire Gause, 365
Wollaston, Dr. W.H. his camera Ine
cida described, 1, 312——_His investi-
gation respecting horizoatal refrae-
tion, 158, 156 ;
Writing ink, 180
W.W. letter from, on the means of
destroying the insects which infest
houses in large towns, 38
W. X.’s*description of a- machine for
triturating quicksilver and combining
it with other substances, 313
Y.
Young, Dr, on the adhesion of bodies
to the surface of fluids, 169
Z.
Zinc, on, 337, et seg.
END OF THE SEVENTEENTH VOLUME,
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