Scientific American Supplement No. 360, November 25, 1882

V >> Various >> Scientific American Supplement No. 360, November 25, 1882

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10

[Illustration: FIG. 4]

The shunt which passes through the fine coil, S', commences at the
point, P. The other end is fixed to the screw, H, whence it has two
paths, the one offering no resistance through the spring, T N, to the
upper negative terminal, A'; the other through the terminal, J, to the
electromagnet of the break, M, and thence to the negative terminal of
the lamp, L'.

[Illustration: FIG. 5.]

_The Cut-off_.--The last part of the apparatus (Fig. 4) to be described
is the cut-off, which is used when there are several lamps in series. It
is brought into play by the switch, C D, which can be placed at E or D.
When it is at E, the negative terminal, A, is in communication with
the positive terminal, B, through the resistance, R, which equals the
resistance of the lamp, which is, therefore, out of circuit. When it is
at D the cut-off acts automatically to do the same thing when required.
This is done by a solenoid, V, which has two coils, the one of thick
wire offering no resistance, and the other of 2,000 ohms resistance. The
fine wire connects the terminals, A' and B. The solenoid has a movable
soft iron core suspended by the spring, U. It has a cross-piece of iron
which can dip into two mercury cups, G and K, when the core is sucked
into the solenoid. When this is the case, which happens when any
accident occurs to the lamp, the terminal, A, is placed in connection
with the terminal, B, through the thick wire of V and the resistance, R,
in the same way as it was done by the switch, C D.

_Electrical Arrangement_.--The mode in which several lamps are connected
up in series is shown by Fig. 6. M is the dynamo machine. The + lead is
connected to B1 of the balance it then passes to the lamp, L, returning
to the balance, and then proceeds to each other lamp, returning finally
to the negative pole of the machine. When the current enters the balance
it passes through the coil, S, magnetizing the iron core and drawing
it downward (Fig. 4). It then passes to the lamp, L L', through the
carbons, then returns to the balance, and proceeds back to the negative
terminal of the machine. A small portion of the current is shunted off
at the point, P, passing through the coil, S', through the contact
spring, T N, to the terminal, A', and drawing the iron core in
opposition to S. The carbons are in contact, but in passing through
the lamp the current magnetizes the electromagnet, M (Fig. 2), which
attracts the armature, A B, that bites and lifts up the rod, T, with the
upper carbon, a definite and fixed distance that is easily regulated
by the screws, Y Y. The arc then is formed, and will continue to burn
steadily as long as the current remains constant. But the moment the
current falls, due to the increased resistance of the arc, a greater
proportion passes through the shunt, S' (Fig. 4), increasing its
magnetic moment on the iron core, while that of S is diminishing. The
result is that a moment arrives when equilibrium is destroyed, the iron
rod strikes smartly and sharply upon the spring, N T. Contact between T
and H is broken, and the current passes through the electromagnet of the
break in the lamp. The break is released for an instant, the carbons
approach each other. But the same rupture of contact introduces in the
shunt a new resistance of considerable magnitude (viz., 1,200 ohms),
that of the electromagnets of the break. Then the strength of the shunt
current diminishes considerably, and the solenoid, S, recovers briskly
its drawing power upon the rod, and contact is restored. The carbons
approach during these periods only about 0.01 to 0.02 millimeter.
If this is not sufficient to restore equilibrium it is repeated
continually, until equilibrium is obtained. The result is that the
carbon is continually falling by a motion invisible to the eye, but
sufficient to provide for the consumption of the carbons.

[Illustration: FIG. 6]

The contact between N T and H is never completely broken, the sparks are
very feeble, and the contacts do not oxidize. The resistances inserted
are so considerable that heating cannot occur, while the portion of the
current abstracted for the control is so small that it may be neglected.

The balance acts precisely like the key of a Morse machine, and the
break precisely like the sounder-receiver so well known in telegraphy.
It emits the same kind of sounds, and acts automatically like a skilled
and faithful telegraphist.

This regulation, by very small and short successive steps, offers
several advantages: (1) it is imperceptible to the eye; (2) it does not
affect the main current; (3) any sudden instantaneous variation of the
main current does not allow a too near approach of the carbon points.
Let, now, an accident occur; for instance, a carbon is broken. At once
the automatic cut-off acts, the current passes through the resistance,
R, instead of passing through the lamp. The current through the fine
coil is suddenly increased, the rod is drawn in, contact is made at G
and K, and the current is sent through the coil, R. As soon as contact
is again made by the carbons, the current in the coil, S, is increased,
that of the thick wire in V diminished, and the antagonistic spring,
U, breaks the contact at G and K. The rupture of the light is almost
invisible, because the relighting is so brisk and sharp.

I have seen this lamp in action, and its constant steadiness leaves
nothing to be desired.

* * * * *

APPARATUS FOR OBTAINING PURE WATER FOR PHOTOGRAPHIC USE.

Our readers are well aware that water as found naturally is never
absolutely free from dissolved impurities; and in ordinary cases it
contains solid impurities derived both from the inorganic and organic
kingdoms, together with gaseous substances; these latter being generally
derived from the atmosphere.

By far the purest water which occurs in nature is rain-water, and if
this be collected in a secluded district, and after the air has been
well washed by previous rain, its purity is remarkable; the extraneous
matter consisting of little else than a trace of carbonic acid and other
gases dissolved from the air. In fact, such water is far purer than any
distilled water to be obtained in commerce. The case is very different
when the rain-water is collected in a town or densely populated
district, more especially if the water has been allowed to flow over
dirty roofs. The black and foully-smelling liquid popularly known as
soft water is so rich in carbonaceous and organic constituents as to be
of very limited use to the photographer; but by taking the precaution of
fitting up a simple automatic shunt for diverting the stream until the
roofs have been thoroughly washed, it becomes possible to insure a good
supply of clean and serviceable soft water, even in London. Several
forms of shunt have been devised, some of these being so complex as
to offer every prospect of speedy disorganization; but a simple and
efficient apparatus is figured in _Engineering_ by a correspondent who
signs himself "Millwright," and as we have thoroughly proved the value
of an apparatus which is practically identical, we reproduce the
substance of his communication.

A gentleman of Newcastle, a retired banker, having tried various filters
to purify the rain-water collected on the roof of his house, at length
had the idea to allow no water to run into the cistern until the roof
had been well washed. After first putting up a hard-worked valve, the
arrangement as sketched below has been hit upon. Now Newcastle is a very
smoky place, and yet my friend gets water as pure as gin, and almost
absolutely free from any smack of soot.

[Illustration]

The sketch explains itself. The weight, W, and the angle of the lever,
L, are such, that when the valve, V, is once opened it goes full open. A
small hole in the can C, acts like a cataract, and brings matters to a
normal state very soon after the rain ceases.

The proper action of the apparatus can only be insured by a careful
adjustment of the weight, W, the angle through which the valve opens,
and the magnitude of the vessel, C. It is an advantage to make
the vessel, C, somewhat broader in proportion to its height than
represented, and to provide it with a movable strainer placed about half
way down. This tends to protect the cataract hole, and any accumulation
of leaves and dirt can be removed once in six months or so. Clean soft
water is valuable to the photographer in very many cases. Iron developer
(wet plate) free from chlorides will ordinarily remain effective on the
plate much longer than when chlorides are present, and the pyrogallic
solution for dry-plate work will keep good for along time if made with
soft water, while the lime which is present in hard water causes the
pyrogallic acid to oxidize with considerable rapidity. Negatives that
have been developed with oxalate developer often become covered with a
very unsightly veil of calcium oxalate when rinsed with hard water, and
something of a similar character occasionally occurs in the case of
silver prints which are transferred directly from the exposure frame to
impure water.

To the carbon printer clean rain-water is of considerable value, as he
can develop much more rapidly with soft water than with hard water;
or, what comes to the same thing, he can dissolve away his superfluous
gelatine at a lower temperature than would otherwise be necessary.

The cleanest rain-water which can ordinarily be collected in a town is
not sufficiently pure to be used with advantage in the preparation of
the nitrate bath, it being advisable to use the purest distilled water
for this purpose; and in many cases it is well to carefully distill
water for the bath in a glass apparatus of the kind figured below.

[Illustration]

A, thin glass flask serving as a retort. The tube, T, is fitted
air-tight to the flask by a cork, C.

B, receiver into which the tube, T, fits quite loosely.

D, water vessel intended to keep the spiral of lamp wick, which is shown
as surrounding T, in a moist condition. This wick acts as a siphon, and
water is gradually drawn over into the lower receptacle, E.

L, spirit lamp, which may, in many cases, be advantageously replaced by
a Bunsen burner.

A small metal still, provided with a tin condensing worm, is, however, a
more generally serviceable arrangement, and if ordinary precautions are
taken to make sure that the worm tube is clean, the resulting distilled
water will be nearly as pure as that distilled in glass vessels.

Such a still as that figured below can be heated conveniently over an
ordinary kitchen fire, and should find a place among the appliances
of every photographer. Distilled water should always be used in the
preparation of emulsion, as the impurities of ordinary water may often
introduce disturbing conditions.--_Photographic News_.

[Illustration]

* * * * *

BLACK PHOSPHORUS.

By P. THENARD.

The author refers to the customary view that black phosphorus is
merely a mixture of the ordinary phosphorus with traces of a metallic
phosphide, and contends that this explanation is not in all cases
admissible. A specimen of black or rather dark gray phosphorus, which
the author submitted to the Academy, became white if melted and remained
white if suddenly cooled, but if allowed to enter into a state of
superfusion it became again black on contact with either white or black
phosphorus. A portion of the black specimen being dissolved in carbon
disulphide there remained undissolved merely a trace of a very pale
yellow matter which seemed to be amorphous phosphorus.--_Comptes
Rendus_.

* * * * *

COMPOSITION OF STEEP WATER.

According to M. C. Leeuw, water in which malt has been steeped has the
following composition:

Organic matter. 0.56 per cent.
Mineral matter. 0.52 "
----
Total dry matter. 1.08 "
----
Nitrogen. 0.033 "

The mineral matter consists of--

Potash. 0.193 "
Phosphoric acid. 0.031 "
Lime. 0.012 "
Soda. 0.047 "
Magnesia. 0.016 "
Sulphuric acid. 0.007 "
Oxide of iron. traces.
Chlorine and silica. 0.212 "

* * * * *

SCHREIBER'S APPARATUS FOR REVIVIFYING BONE-BLACK.

We give opposite illustrations of Schreiber's apparatus for revivifying
bone-black or animal charcoal. The object of revivification is to render
the black fit to be used again after it has lost its decolorizing
properties through service--that is to say, to free its pores from the
absorbed salts and insoluble compounds that have formed therein
during the operation of sugar refining. There are two methods
employed--fermentation and washing. At present the tendency is to
abandon the former in order to proceed with as small a stock of black as
possible, and to adopt the method of washing with water and acid in a
rotary washer.

Figs. 1 and 2 represent a plan and elevation of a bone-black room,
containing light filters, A, arranged in a circle around wells, B. These
latter have the form of a prism with trapezoidal base, whose small sides
end at the same point, d, and the large ones at the filter. The funnel,
E, of the washer, F, is placed in the space left by the small ends of
the wells, so that the black may be taken from these latter and thrown
directly into the washer. The washer is arranged so that the black may
flow out near the steam fitter, G, beneath the floor. The discharge of
this filter is toward the side of the elevator, H, which takes in the
wet black below, and carries it up and pours it into the drier situated
at the upper part of the furnace. This elevator, Figs. 3 and 4, is
formed of two vertical wooden uprights, A, ten centimeters in thickness,
to which are fixed two round-iron bars the same as guides. The lift,
properly so-called, consists of an iron frame, C, provided at the four
angles with rollers, D, and supporting a swinging bucket, E, which, on
its arrival at the upper part of the furnace, allows the black to fall
to an inclined plane that leads it to the upper part of the drier. The
left is raised and lowered by means of a pitch-chain, F, fixed to the
middle of the frame, C, and passing over two pulleys, G, at the upper
part of the frame and descending to the mechanism that actuates it.
This latter comprises a nut, I, acting directly on the chain; a toothed
wheel, K, and a pinion, J, gearing with the latter and keyed upon the
shaft of the pulleys, L and M. The diameter of the toothed wheel, K, is
0.295 of a meter, and it makes 53.4 revolutions per minute. The diameter
of the pinion is 0.197 of a meter, and it makes 80 revolutions per
minute. The pulleys, M and L, are 0.31 of a meter in diameter, and
make 80 revolutions per minute. Motion is transmitted to them by other
pulleys, N, keyed upon a shaft placed at the lower part, which receives
its motion from the engine of the establishment through the intermedium
of the pulley, O. The diameter of the latter is 0.385 of a meter, and
that of N is 0.58. They each make 43 revolutions per minute.

[Illustration: FIG. 1.--ELEVATION OF BONE-BLACK REVIVIFYING PLANT
(SCHREIBER'S SYSTEM.)

FIG. 2.--PLAN VIEW.

FIG. 3.--LATERAL VIEW OF ELEVATOR.

FIG. 4.--FRONT VIEW OF ELEVATOR.

FIG. 5.--CONTINUOUS FURNACE FOR REVIVIFYING BONE-BLACK.]

The elevator is set in motion by the simple maneuver of the gearing
lever, P, and when this has been done all the other motions are effected
automatically.

_The Animal Black Furnace_.--This consists of a masonry casing of
rectangular form, in which are arranged on each side of the same
fire-place two rows of cast-iron retorts, D, of undulating form, each
composed of three parts, set one within the other. These retorts, which
serve for the revivification of the black, are incased in superposed
blocks of refractory clay, P, Q, S, designed to regularize the
transmission of heat and to prevent burning. These pieces are kept in
their respective places by crosspieces, R. The space between the retorts
occupied by the fire-place, Y, is covered with a cylindrical dome, O, of
refractory tiles, forming a fire-chamber with the inner surface of the
blocks, P, Q, and S. The front of the surface consists of a cast-iron
plate, containing the doors to the fire-place and ash pan, and a larger
one to allow of entrance to the interior to make repairs.

One of the principal disadvantages of furnaces for revivifying animal
charcoal has been that they possessed no automatic drier for drying the
black on its exit from the washer. It was for the purpose of remedying
this that Mr. Schreiber was led to invent the automatic system of drying
shown at the upper part of the furnace, and which is formed of two
pipes, B, of undulating form, like the retorts, with openings throughout
their length for the escape of steam. Between these pipes there is a
closed space into which enters the waste heat and products of combustion
from the furnace. These latter afterward escape through the chimney at
the upper part.

In order that the black may be put in bags on issuing from the furnace,
it must be cooled as much as possible. For this purpose there are
arranged on each side of the furnace two pieces of cast iron tubes, F,
of rectangular section, forming a prolongation of the retorts and making
with them an angle of about 45 degrees. The extremities of these tubes
terminate in hollow rotary cylinders, G, which permit of regulating the
flow of the black into a car, J (Fig. 1), running on rails.

From what precedes, it will be readily understood how a furnace is run
on this plan.

The bone-black in the hopper, A, descends into the drier, B, enters the
retorts, D, and, after revivification, passes into the cooling pipes, F,
from whence it issues cold and ready to be bagged. A coke fire having
been built in the fire-place, Y, the flames spread throughout the fire
chamber, direct themselves toward the bottom, divide into two parts to
the right and left, and heat the back of the retorts in passing. Then
the two currents mount through the lateral flues, V, and unite so as to
form but one in the drier. Within the latter there are arranged plates
designed to break the current from the flames, and allow it to heat all
the inner parts of the pipes, while the apertures in the drier allow of
the escape of the steam.

By turning one of the cylinders, G, so as to present its aperture
opposite that of the cooler, it instantly fills up with black. At this
moment the whole column, from top to bottom, is set in motion. The
bone-black, in passing through the undulations, is thrown alternately to
the right and left until it finally reaches the coolers. This operation
is repeated as many times as the cylinder is filled during the descent
of one whole column, that is to say, about forty times.

With an apparatus of the dimensions here described, 120 hectoliters
of bone-black may be revivified in twenty four hours, with 360 to 400
kilogrammes of coke.--_Annales Industrielles_.

* * * * *

[Continued from SUPPLEMENT, No. 330, page 5264.]

SOAP AND ITS MANUFACTURE, FROM A CONSUMER'S POINT OF VIEW.

In our last article, under the above heading, the advantages to be
gained by the use of potash soap as compared with soda soap were pointed
out, and the reasons of this superiority, especially in the case of
washing wool or woolen fabrics, were pretty fully gone into. It was also
further explained why the potash soaps generally sold to the public were
unfit for general use, owing to their not being neutral--that is to say,
containing a considerable excess of free or unsaponified alkali, which
acts injuriously on the fiber of any textile material, and causes sore
hands if used for household or laundry purposes. It was shown that the
cause of this defect was owing to the old-fashioned method of making
potash or soft soap, by boiling with wood ashes or other impure form of
potash; but that a perfectly pure and neutral potash soap could readily
be made with pure caustic potash, which within the last few years has
become a commercial article, manufactured on a large scale; just in
the same manner as the powdered 98 per cent. caustic soda, which was
recommended in our previous articles on making hard soap without
boiling.

The process of making pure neutral potash soap is very simple, and
almost identical with that for making hard soap with pure powdered
caustic soda. The following directions, if carefully and exactly
followed, will produce a first-class potash soap, suitable either for
the woolen manufacturer for washing his wool, and the cloth afterward
made from it, or for household and laundry purposes, for which uses it
will be found far superior to any soda soap, no matter how pure or well
made it may be.

Dissolve twenty pounds of pure caustic potash in two gallons of water.
Pure caustic potash is very soluble, and dissolves almost immediately,
heating the water. Let the lye thus made cool until warm to the
hand--say about 90 F. Melt eighty pounds of tallow or grease, which must
be free from salt, and let it cool until fairly hot to the hand--say
130 F.; or eighty pounds of any vegetable or animal oil may be taken
instead. Now pour the caustic potash lye into the melted tallow or oil,
stirring with a flat wooden stirrer about three inches broad, until both
are thoroughly mixed and smooth in appearance. This mixing may be done
in the boiler used to melt the tallow, or in a tub, or half an oil
barrel makes a good mixing vessel. Wrap the tub or barrel well up in
blankets or sheepskins, and put away for a week in some warm dry place,
during which the mixture slowly turns into soap, giving a produce of
about 120 pounds of excellent potash soap. If this soap is made with
tallow or grease it will be nearly as hard as soda soap. When made by
farmers or householders tallow or grease will generally be taken, as it
is the cheapest, and ready to hand on the spot. For manufacturers, or
for making laundry soap, nothing could be better than cotton seed oil. A
magnificent soap can be made with this article, lathering very freely.
When made with oil it is better to remelt in a kettle the potash soap,
made according to the above directions, with half its weight of water,
using very little heat, stirring constantly, and removing the fire as
soon as the water is mixed with and taken up by the soap. A beautifully
bright soap is obtained in this way, and curiously the soap is actually
made much harder and stiffer by this addition of water than when it is
in a more concentrated state previously to the water being added.

With reference to the caustic potash for making the soap, it can be
obtained in all sizes of drums, but small packages just sufficient for
a batch of soap are generally more economical than larger packages, as
pure caustic potash melts and deteriorates very quickly when exposed
to the air. The Greenbank Alkali Co., of St. Helens, seems to have
appreciated this, and put upon the market pure caustic potash in twenty
pound canisters, which are very convenient for potash soft soap making
by consumers for their own use.

While on this subject of caustic potash, it cannot be too often repeated
that _caustic potash_ is a totally different article to _caustic soda_,
though just like it in appearance, and therefore often sold as such.
One of the most barefaced instances of this is the so-called "crystal
potash," "ball potash," or "rock potash," of the lye packers, sold in
one pound packages, which absolutely, without exception, do not contain
a single grain of potash, but simply consist of caustic soda more or
less adulterated--as a rule very much "more" than "less!" It is much
to be regretted that this fraud on the public has been so extensively
practiced, as potash has been greatly discredited by this procedure.

The subject of fleece scouring or washing the wool while growing on
the sheep, with a potash soap made on the spot with the waste tallow
generally to be had on every sheep farm, seems recently to have been
attracting attention in some quarters, and certainly would be a source
of profit to sheep owners by putting their wool on the market in the
best condition, and at the same time cleaning the skin of the sheep. It
therefore appears to be a move in the right direction.

In concluding this series of articles on practical soap making from a
consumer's point of view, the writer hopes that, although the subject
has been somewhat imperfectly handled, owing to necessarily limited
space and with many unavoidable interruptions, yet that they may have
been found of some interest and assistance to consumers of soap who
desire easily and readily to make a pure and unadulterated article for
their own use.

* * * * *

COTTON SEED OIL.

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10