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SCIENTIFIC AMERICAN SUPPLEMENT NO. 441




NEW YORK, JUNE 14, 1884

Scientific American Supplement. Vol. XVII., No. 441.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

* * * * *




TABLE OF CONTENTS.


I. CHEMISTRY AND METALLURGY. - On Electrolysis. - Precipitation
of lead, thallium, silver, bismuth, manganese, etc. - By H.
SCHUCHT

The Electro-Chemical Equivalent of Silver

Zircon. - How it can be rendered soluble. - By F. STOLBA

A New Process for Making Wrought Iron Directly from the Ore.
- Comparison with other processes. - With descriptions and
engravings of the apparatus used

Some Remarks on the Determination of Hardness in Water

On the changes which Take Place in the Conversion of Hay
into Ensilage. - By F.J. Lloyd

II. ENGINEERING AND MECHANICS. - Faure's Machine for
Decorticating Sugar Cane. - With full description
and 13 figures

The Generation of Steam and the Thermodynamic Problems
Involved. - By WM. ANDERSON. - Apparatus used in the
experimental determination of the heat of combustion and
the laws which govern its development. - Ingredients of
fuel. - Potential energy of fuel. - With 7 figures and
several tables

Planetary Wheel Trains. - Rotations of the wheels relatively
to the train arm. - By Prof. C.W. MACCORD

The Pantanemone. - A New Windwheel. - 1 engraving

Relvas's New Life Boat. - With engraving

Experiments with Double Barreled Guns and Rifles.
- Cause of the divergence of the charge. - 4 figures

Improved Ball Turning Machine. - 1 figure

Cooling Apparatus for Injection Water. - With engraving

Corrugated Disk Pulleys. - 1 engraving

III. TECHNOLOGY. - A New Standard Light

Dr. Feussner's New Polarizing Prism. - Points of difference
between the old and new prisms. - By P.R. SLEEMAN

Density and Pressure of Detonating Gas

IV. ELECTRICITY, LIGHT, ETC. - Early History of the Telegraph.
- Pyrsia, or the system of telegraphy among the Greeks.
- Communication by means of characters and the telescope.
- Introduction of the magnetic telegraph between Baltimore
and Washington

The Kravogl Electro Motor and its Conversion Into a Dynamo
Electric Machine. - 5 figures

Bornhardt's Electric Machine for Blasting in Mines.
- 15 figures

Pritchett's Electric Fire Alarm. - 1 figure

A Standard Thermopile

Telephonic Transmission without Receivers. - Some of the
apparatus exhibited at the annual meeting of the French
Society of Physics. - Telephonic transmission through a
chain of persons

Diffraction Phenomena during Total Solar Eclipses. - By G.D.
Hiscox

V. BOTANY AND HORTICULTURE. - Gum Diseases in Trees. -
Cause and contagion of the same

Drinkstone Park. - Trees and plants cultivated therein. -
With 2 engravings

VI. MEDICINE AND HYGIENE. - Miryachit. - A newly-discovered
disease of the nervous system, and its analogues. - By WM. A.
HAMMOND

VII. MISCELLANEOUS. - Turkish Baths for Horses. - With
diagram.

* * * * *




FAURE'S MACHINE FOR DECORTICATING SUGAR-CANE.


The object of the apparatus shown in the accompanying engraving is to
effect a separation of the tough epidermis of the sugar-cane from the
internal spongy pith which is to be pressed. Its function consists in
isolating and separating the cells from their cortex, and in putting
them in direct contact with the rollers or cylinders of the mill.
After their passage into the apparatus, which is naturally placed in a
line with the endless chain that carries them to the mill, the canes
arrive in less compact layers, pass through much narrower spaces, and
finally undergo a more efficient pressure, which is shown by an
abundant flow of juice. The first trials of the machine were made in
1879 at the Pointe Simon Works, at Martinique, with the small type
that was shown at the Paris Exhibition of 1878. These experiments,
which were applied to a work of 3,000 kilos of cane per hour, gave
entire satisfaction, and decided the owners of three of the colonial
works (Pointe Simon, Larcinty, and Marin) to adopt it for the season
of 1880.

The apparatus is shown in longitudinal section in Fig. 1, and in plan
in Fig. 2.

Fig. 3 gives a transverse section passing through the line 3-4, and
Fig. 4 an external view on the side whence the decorticated canes make
their exit from the apparatus.

[Illustration: FAURE'S MACHINE FOR DECORTICATING SUGAR CANE.]

The other figures relate to details that will be referred to further
along.

_The Decorticating Cylinder._ - The principal part of the apparatus is
a hollow drum, A, of cast iron, 430 mm. in internal diameter by 1.41
m. in length, which is keyed at its two extremities to the shaft, a.
Externally, this drum (which is represented apart in transverse
section in Fig. 5) has the form of an octagonal prism with well
dressed projections between which are fixed the eight plates, C, that
constitute the decorticating cylinder. These plates, which are of
tempered cast iron, and one of which is shown in transverse section in
Fig. 7, when once in place form a cylindrical surface provided with 48
helicoidal, dentate channels. The length of these plates is 470 mm.
There are three of them in the direction of the generatrices of the
cylinder, and this makes a total of 24. All are strengthened by ribs
(as shown in Fig. 8), and each is fixed by 4 bolts, _c_, 20mm. in
diameter. The pitch of the helices of each tooth is very elongated,
and reaches about 7.52 m. The depth of the toothing is 18 mm.

_Frame and Endless Chain._ - The cylinder thus constructed rotates with
a velocity of 50 revolutions per minute over a cylindrical vessel, B',
cast in a piece with the frame, B. This vessel is lined with two
series of tempered cast iron plates, D and D', called exit and
entrance plates, which rest thereon, through the intermedium of well
dressed pedicels, and which are held in place by six 20-millimeter
bolts. Their length is 708 mm. The entrance plates, D, are provided
with 6 spiral channels, whose pitch is equal to that of the channels
of the decorticating cylinder, C, and in the same direction. The depth
of the toothing is 10 mm.

The exit plates, D', are provided with 7 spiral channels of the same
pitch and direction as those of the preceding, but the depth of which
increases from 2 to 10 mm. The axis of the decorticating cylinder does
not coincide with that of the vessel, B', so that the free interval
for the passage of the cane continues to diminish from the entrance to
the exit.

The passage of the cane to the decorticator gives rise to a small
quantity of juice, which flows through two orifices, _b'_, into a sort
of cast iron trough, G, suspended beneath the vessel. The cane, which
is brought to the apparatus by an endless belt, empties in a conduit
formed of an inclined bottom, E, of plate iron, and two cast iron
sides provided with ribs. These sides rest upon the two ends of the
vessel, B', and are cross-braced by two flat bars, _e_, to which is
bolted the bottom, E. This conduit is prolonged beyond the
decorticating cylinder by an inclined chute, F, the bottom of which is
made of plate iron 7 mm. thick and the sides of the same material 9
mm. thick. The hollow frame, B, whose general form is like that of a
saddle, carries the bearings, _b_, in which revolves the shaft, _a_.
One of these bearings is represented in detail in Figs. 9 and 10. It
will be seen that the cap is held by bolts with sunken heads, and that
the bearing on the bushes is through horizontal surfaces only. In a
piece with this frame are cast two similar brackets, B², which support
the axle, _h_, of the endless chain. To this axle, whose diameter is
100 mm., are keyed, toward the extremities, the pinions, H, to which
correspond the endless pitch chains, _i_. These latter are formed, as
may be seen in Figs. 11 and 12, of two series of links. The shorter of
these latter are only 100 mm. in length, while the longer are 210 mm.,
and are hollowed out so as to receive the butts of the boards, I. The
chain thus formed passes over two pitch pinions, J, like the pinions,
H, that are mounted at the extremities of an axle, _j_, that revolves
in bearings, I', whose position with regard to the apparatus is
capable of being varied so as to slacken or tauten the chain, I. This
arrangement is shown in elevation in Fig. 13.

_Transmission._ - The driving shaft, _k_, revolves in a pillow block,
K, cast in a piece with the frame, B. It is usually actuated by a
special motor, and carries a fly-wheel (not shown in the figure for
want of space). It receives in addition a cog-wheel, L, which
transmits its motion to the decorticating cylinder through, the
intermedium of a large wooden-toothed gear wheel, L'. The shaft, _a_,
whose diameter is 228 mm., actuates in its turn, through the pinions,
M' and M, the pitch pinion, N, upon whose prolonged hub is keyed the
pinion, M. This latter is mounted loosely upon the intermediate axle,
_m_. Motion is transmitted to the driving shaft, _h_, of the endless
chain, I, by an ordinary pitch chain, through a gearing which is shown
in Fig. 12. The pitch pinion, N', is cast in a piece with a hollow
friction cone, N², which is mounted loosely upon the shaft, _h_, and
to which corresponds a second friction cone, O. This latter is
connected by a key to a socket, _o_, upon which it slides, and which
is itself keyed to the shaft, _h_. The hub of the cone, O, is
connected by a ring with a bronze nut, _p_, mounted at the threaded
end of the shaft, _h_, and carrying a hand-wheel, P. It is only
necessary to turn this latter in one direction or the other in order
to throw the two cones into or out of gear.

If we allow that the motor has a velocity of 70 revolutions per
minute, the decorticating cylinder will run at the rate of 50, and the
sugar-cane will move forward at the rate of 12 meters per minute.

This new machine is a very simple and powerful one. The decortication
is effected with wonderful rapidity, and the canes, opened throughout
their entire length and at all points of their circumference, leave
the apparatus in a state that allows of no doubt as to what the result
of the pressure will be that they have to undergo. There is no
tearing, no trituration, no loss of juice, but merely a simple
preparation for a rational pressure effected under most favorable
conditions.

The apparatus, which is made in several sizes, has already received
numerous applications in Martinique, Trinidad, Cuba, Antigua, St.
Domingo, Peru, Australia, the Mauritius Islands, and
Brazil. - _Publication Industrielle._

* * * * *




MOVING A BRIDGE.


An interesting piece of engineering work has recently been
accomplished at Bristol, England, which consisted in the moving of a
foot-bridge 134 feet in length, bodily, down the river a considerable
distance. The pontoons by means of which the bridge was floated to its
new position consisted of four 80-ton barges, braced together so as to
form one solid structure 64 feet in width, and were placed in position
soon after the tide commenced to rise. At six o'clock A.M. the top of
the stages, which was 24 feet above the water, touched the under part
of the bridge, and in a quarter of an hour later both ends rose from
their foundations. When the tide had risen 4 ft. the stage and bridge
were floated to the new position, when at 8.30 the girders dropped on
to their beds.

* * * * *




THE GENERATION OF STEAM, AND THE THERMODYNAMIC PROBLEMS
INVOLVED.[1]

[Footnote 1: Lecture delivered at the Institution of Civil
Engineers, session 1883-84. For the illustrations we are indebted
to the courtesy of Mr. J. Forrest, the secretary.]

By Mr. WILLIAM ANDERSON, M.I.C.E.


It will not be necessary to commence this lecture by explaining the
origin of fuel; it will be sufficient if I remind you that it is to
the action of the complex rays of the sun upon the foliage of plants
that we mainly owe our supply of combustibles. The tree trunks and
branches of our forests, as well as the subterranean deposits of coal
and naphtha, at one time formed portions of the atmosphere in the form
of carbonic acid gas; that gas was decomposed by the energy of the
solar rays, the carbon and the oxygen were placed in positions of
advantage with respect to each other - endowed with potential energy;
and it is my duty this evening to show how we can best make use of
these relations, and by once more combining the constituents of fuel
with the oxygen of the air, reverse the action which caused the growth
of the plants, that is to say, by destroying the plant reproduce the
heat and light which fostered it. The energy which can be set free by
this process cannot be greater than that derived originally from the
sun, and which, acting through the frail mechanism of green leaves,
tore asunder the strong bonds of chemical affinity wherein the carbon
and oxygen were hound, converting the former into the ligneous
portions of the plants and setting the latter free for other uses. The
power thus silently exerted is enormous; for every ton of carbon
separated in twelve hours necessitates an expenditure of energy
represented by at least 1,058 horse power, but the action is spread
over an enormous area of leaf surface, rendered necessary by the small
proportion of carbonic acid contained in the air, by measure only
1/2000 part, and hence the action is silent and imperceptible. It is
now conceded on all hands that what is termed heat is the energy of
molecular motion, and that this motion is convertible into various
kinds and obeys the general laws relating to motion. Two substances
brought within the range of chemical affinity unite with more or less
violence; the motion of transition of the particles is transformed,
wholly or in part, into a vibratory or rotary motion, either of the
particles themselves or the interatomic ether; and according to the
quality of the motions we are as a rule, besides other effects, made
conscious of heat or light, or of both. When these emanations come to
be examined they are found to be complex in the extreme, intimately
bound up together, and yet capable of being separated and analyzed.

As soon as the law of definite chemical combination was firmly
established, the circumstance that changes of temperature accompanied
most chemical combinations was noticed, and chemists were not long in
suspecting that the amount of heat developed or absorbed by chemical
reaction should be as much a property of the substances entering into
combination as their atomic weights. Solid ground for this expectation
lies in the dynamic theory of heat. A body of water at a given height
is competent by its fall to produce a definite and invariable quantity
of heat or work, and in the same way two substances falling together
in chemical union acquire a definite amount of kinetic energy, which,
if not expended in the work of molecular changes, may also by suitable
arrangements be made to manifest a definite and invariable quantity of
heat.

At the end of last century Lavoisier and Laplace, and after them, down
to our own time, Dulong, Desprez, Favre and Silbermann, Andrews,
Berthelot, Thomson, and others, devoted much time and labor to the
experimental determination of the heat of combustion and the laws
which governed its development. Messrs. Favre and Silbermann, in
particular, between the years 1845 and 1852, carried out a splendid
series of experiments by means of the apparatus partly represented in
Fig. 1 (opposite), which is a drawing one-third the natural size of
the calorimeter employed. It consisted essentially of a combustion
chamber formed of thin copper, gilt internally. The upper part of the
chamber was fitted with a cover through which the combustible could be
introduced, with a pipe for a gas jet, with a peep hole closed by
adiathermanous but transparent substances, alum and glass, and with a
branch leading to a thin copper coil surrounding the lower part of the
chamber and descending below it. The whole of this portion of the
apparatus was plunged into a thin copper vessel, silvered internally
and filled with water, which was kept thoroughly mixed by means of
agitators. This second vessel stood inside a third one, the sides and
bottom of which were covered with the skins of swans with the down on,
and the whole was immersed in a fourth vessel tilled with water, kept
at the average temperature of the laboratory. Suitable thermometers of
great delicacy were provided, and all manner of precautions were taken
to prevent loss of heat.

[Illustration: THE GENERATION OF STEAM. Fig 1.]

It is impossible not to admire the ingenuity and skill exhibited in
the details of the apparatus, in the various accessories for
generating and storing the gases used, and for absorbing and weighing
the products of combustion; but it is a matter of regret that the
experiments should have been carried out on so small a scale. For
example, the little cage which held the solid fuel tested was only 5/8
inch diameter by barely 2 inches high, and held only 38 grains of
charcoal, the combustion occupying about sixteen minutes. Favre and
Silbermann adopted the plan of ascertaining the weight of the
substances consumed by calculation from the weight of the products of
combustion. Carbonic acid was absorbed by caustic potash, as also was
carbonic oxide, after having been oxidized to carbonic acid by heated
oxide of copper, and the vapor of water was absorbed by concentrated
sulphuric acid. The adoption of this system showed that it was in any
case necessary to analyze the products of combustion in order to
detect imperfect action. Thus, in the case of substances containing
carbon, carbonic oxide was always present to a variable extent with
the carbonic acid, and corrections were necessary in order to
determine the total heat due to the complete combination of the
substance with oxygen. Another advantage gained was that the
absorption of the products of combustion prevents any sensible
alteration in the volumes during the process, so that corrections for
the heat absorbed in the work of displacing the atmosphere were not
required. The experiments on various substances were repeated many
times. The mean results for those in which we are immediately
interested are given in Table I., next column.

Comparison with later determinations have established their
substantial accuracy. The general conclusion arrived at is thus
stated:

"As a rule there is an equality between the heat disengaged or
absorbed in the acts, respectively, of chemical combination or
decomposition of the same elements, so that the heat evolved during
the combination of two simple or com-pound substances is equal to the
heat absorbed at the time of their chemical segregation."

TABLE I. - SUBSTANCES ENTERING INTO THE COMPOSITION OF FUEL.

- - - - - - - - - - - -+ - - - - - - -+ - - - - - -+ - - - - - - - - - -+
| | Heat evolved in |
| Symbol and Atomic |the Combustion of |
| Weight. | 1 lb. of Fuel. |
+ - - - - - - + - - - - - - + - - - - + - - - - - +
| | | |In Pounds |
| | | In | of Water |
| | |British |Evaporated|
| Before | After |Thermal | from and |
| Combustion | Combustion | Units. | at 212°. |
+ - - - - - - + - - - - - - + - - - - + - - - - - +
Hydrogen burned | H 1 | H2O 18 | 62,032 | 64.21 |
in oxygen. | | | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +
Carbon burned to | C 12 | CO 28 | 4,451 | 4.61 |
carbonic oxide. | | | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +
Carbon burned to | C 12 | CO2 44 | 14,544 | 15.06 |
carbonic acid. | | | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +
Carbonic oxide burned | CO 28 | CO2 44 | 4,326 | 4.48 |
to carbonic acid. | | | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +
Olefiant gas (ethylene)| C2H4 28 | 2CO2 124 | 21,343 | 22.09 |
burnt in oxygen. | | 2H2O | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +
Marsh gas (methane) | CH4 16 | 2CO2 80 | 23,513 | 24.34 |
burnt in oxygen. | | 2H2O | | |
- - - - - - - - - - - -+ - - - - - - + - - - - - - + - - - - + - - - - - +

Composition of air -

by volume 0.788 N + 0.197 O + 0.001 CO2 + 0.014 H2O
- - - - - - - - - - - - - - - - - - - - - - - - - -
by weight 0.771 N + 0.218 O + 0.009 CO2 + 0.017 H2O

This law is, however, subject to some apparent exceptions. Carbon
burned in protoxide of nitrogen, or laughing gas, N_{2}O, produces
about 38 per cent. more heat than the same substance burned in pure
oxygen, notwithstanding that the work of decomposing the protoxide of
nitrogen has to be performed. In marsh gas, or methane, CH_{4}, again,
the energy of combustion is considerably less than that due to the
burning of its carbon and hydrogen separately. These exceptions
probably arise from the circumstance that the energy of chemical
action is absorbed to a greater or less degree in effecting molecular
changes, as, for example, the combustion of 1 pound of nitrogen to
form protoxide of nitrogen results in the absorption of 1,157 units of
heat. Berthelot states, as one of the fundamental principles of
thermochemistry, "that the quantity of heat evolved is the measure of
the sum of the chemical and physical work accomplished in the
reaction"; and such a law will no doubt account for the phenomena
above noted. The equivalent heat of combustion of the compounds we
have practically to deal with has been experimentally determined, and
therefore constitutes a secure basis on which to establish
calculations of the caloric value of fuel; and in doing so, with
respect to substances composed of carbon, hydrogen, and oxygen, it is
convenient to reduce the hydrogen to its heat-producing equivalent of
carbon. The heat of combustion of hydrogen being 62,032 units, that of
carbon 14,544 units, it follows that 4.265 times the weight of
hydrogen will represent an equivalent amount of carbon. With respect
to the oxygen, it is found that it exists in combination with the
hydrogen in the form of water, and, being combined already, abstracts
its combining equivalent of hydrogen from the efficient ingredients of
the fuel; and hence hydrogen, to the extent of 1/8 of the weight of
the oxygen, must be deducted. The general formula then becomes:

Heat of combustion = 14,544 {C + 4.265 (H-(O/8))},

and water evaporated from and at 212°, taking 966 units as the heat
necessary to evaporate 1 pound of water,

lb. evaporated = 15.06 {C + 4.265 (H-(O/8))},

carbon, hydrogen, and oxygen being taken at their weight per cent. in
the fuel. Strictly speaking, marsh gas should be separately
determined. It often happens that available energy is not in a form in
which it can be applied directly to our needs. The water flowing down
from the mountains in the neighborhood of the Alpine tunnels was
competent to provide the power necessary for boring through them, but
it was not in a form in which it could be directly applied. The
kinetic energy of the water had first to be changed into the potential
energy of air under pressure, then, in that form, by suitable
mechanism, it was used with signal success to disintegrate and
excavate the hard rock of the tunnels. The energy resulting from
combustion is also incapable of being directly transformed into useful


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Online LibraryVariousScientific American Supplement, No. 441, June 14, 1884 → online text (page 1 of 10)