Scientific American Supplement, No. 303

V >> Various >> Scientific American Supplement, No. 303

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

The break reels are clothed as follows: First break No. 20, wire cloth,
second break No. 22, third break No. 24, and fourth break No. 24. The
material passing through these scalping reels, now called chop, goes to
a series of reels, the first clothed with Nos. 6, 4, and 0. The material
passing over the tail is sent to the germ purifier, that passing through
Nos. 4 and 0, to the coarse middlings purifier, and that through the No.
6 goes to the reel below clothed with Nos. 12 and 13. Some nice granular
flour is taken off from this reel; the remainder, which passes over the
tail and through the cutoffs, goes to the next reel below clothed with
Nos. 14, 15, and 9. Some good flour comes from the 14 and 15; that which
passes through the 9 goes at once to the stones without purifying, while
that which passes over the tail is sent to the fine middlings purifiers.

After the purification, the middlings are ground on stones and bolted
on Nos. 13 and 14 cloth, after having been scalped on No 8. The germ
middlings are crushed on smooth rolls and bolted on Nos. 12 and 13. What
is not crushed fine enough goes with poor tailings to the second germ
rolls, and from these to a reel by themselves or to the fifth reduction
or bran reel. A mill of this kind could be made much more perfect by an
expenditure of two or three thousands dollars more. I have instanced it
to show what can be done with gradual reduction in a very small way.

In mills of from three hundred to five hundred barrels capacity and
still larger, the programme differs considerably from that I have
sketched, the middlings being graded and handled with little, if any,
returning, and are sized down on the smooth rolls, a much larger
percentage of the work of flouring being done on millstones. For a three
hundred barrel roller mill, the following plant is requisite: five
double corrugated roller mills, five double smooth roller mills, three
pairs of four foot burrs sixteen purifiers, four wire scalping reels,
six feet long, one reel for the fifth break, one reel for low grade
flour, eight chop reels, seven reels for flour from smooth rolls, three
reels for the stone flour, two grading reels, three flour packers, and
necessary cleaning machinery. The reels are eighteen feet thirty-two
inches. The programme is necessarily more complicated.

When it comes to the machinery to be employed in making the reductions
or breaks, the miller has several styles from which to choose. Which is
best comes under the head of what I don't know, and moreover, of that
which I have found no one else who does know. Each machine has its good
points, and the mill owner must make his own decision as to which is
best suited to his purpose. The main principles involved are to abrade
the bran as little as possible while cleaning it thoroughly, and to make
as little break flour, and as many middlings as possible, the latter to
be made in such shape as to be the most easily purified. Regarding
the difference between spring and winter wheat for gradual reduction
milling, it may be stated something after this manner: Spring wheat
has a thinner and more tender bran, makes more middlings because it is
harder, and for the same reason the flour is more inclined to be coarse
and granular. In milling with winter wheat, especially the better
varieties, there will be more break flour made, the middlings will be
finer with fewer bran specks, and the bran more easily cleaned, because
it will stand harsher treatment. Winter wheat, moreover, requires more
careful handling in making the breaks, not because of the bran, but to
avoid breaking down the middlings, and making too much and too fine and
soft break flour. In order to keep the flour sharp and granular, coarser
cloths are used in bolting, and because the middlings are finer the
bolting is not so free and a larger bolting surface is required. In
milling either spring or winter wheat there should be ample purifying
capacity, it being very unwise to limit the number of machines, so that
any of them will be overtaxed. The day has gone by when one purifier
will take care of all the middlings in the mill.

There is one point which is of much interest to mill owners who wish to
change their mills over to the gradual reduction process, that is, how
far they can utilize their present plan of milling machinery in making
the change. Of course the cleaning machinery is the same In both cases,
so are the elevators, conveyors, bolting chests, etc. But to use the
millstone is a debatable question. After carefully considering the
matter I have come to the conclusion that it has its place, and an
important one at that, under the new regime, viz., that of reducing
the finer purified middlings to flour. The reason for this lies in the
peculiar construction of the wheat berry. If the interior of the berry
were one solid mass of flour, needing only to be broken up to the
requisite fineness, it could be done as well on the rolls. But instead
of this, as is well known, the flour part of the berry is made up of
a large number of granules or cells, the walls of which are cellular
tissue, different from the bran in that it is soft and white instead of
hard and dark colored. It is also fibrous to a certain extent, and when
the fine middlings are passed between the rolls instead of breaking
down and becoming finer, it has a tendency to cake up and flatten out,
rendering the flour soft and flaky. It does not hurt the color, but it
does hurt the strength. When the millstone is used in place of the roll
the flour is of equally good color, and more round and granular. I
know that in this the advocates of smooth rolls will differ from my
conclusions, but I believe that the final outcome will be the use of
millstones on the finer middlings, and in fact on all the middlings that
are thoroughly freed from the germ.

It has been said that that which a man gives the most freely and
receives with the worst grace is advice. I will, however, close with a
little of the article which may not be wholly put of place. If you have
a mill do not imagine that the addition of a few pairs of rolls, a
purifier or two, and a little overhauling of bolting-chests, is going to
make it a full-fledged Hungarian roller mill. If you are going to change
an old mill or build a new one, do not take the counsel or follow the
plans of every itinerant miller or millwright who claims to know all
about gradual reduction. No matter what kind of a mill you want to
build, go to some milling engineer who has a reputation for good work,
tell him how large a mill you want, show him samples of the wheat it
must use and the grades of flour it must make, and have him make a
programme for the mill and plan the machinery to fit it. Then have the
mill built to fit the machinery. When it starts follow the programme,
whether it agrees with your preconceived notions or not, and the mill
will, in ninety-nine cases out of one hundred, do good work.

* * * * *

MACHINE FOR DOTTING TULLES AND OTHER LIGHT FABRICS.

Dotted or chenilled tulles are fabrics extensively used in the toilet
of ladies, and the ornamentation of which has hitherto been done by
the application to the tissue, by hand, either of chenille or of small
circles previously cut out of velvet. This work, which naturally takes
considerable time, greatly increases the cost price of the article.

A few trials at doing the work mechanically have been made, but without
any practical outcome. The workwomen who do the dotting are paid at
Lyons at the rate of 80 centimes per 100 dots; so that if we take
tulle with dots counter-simpled 0.04 of an inch, which is the smallest
quincunx used, and suppose that the tissue is 31 inches wide and that
the daily maximum production is one yard, we find that 400 dots at 80
centimes per 100 = 3 francs and 20 centimes (about 63 cents), the cost
of dotting per yard. It is true that the workwoman furnishes the velvet
herself.

Mr. C. Ricanet, of Lyons, has recently invented a machine with which he
effects mechanically the different operations of dotting, not only on
tulles but also upon gauzes or any other light tissues whatever, such
as those of cotton, silk, wool, etc. Aided by a talented mechanic, Mr.
Ricanet has succeeded in constructing one of those masterpieces of
wonderfully accurate mechanism of which the textile industry appears
to have the monopoly--at least it is permissible to judge so from the
remarkable inventions of Vaucanson, Jacquard, Philippe de Girard,
Heilmann, and others.

The object of this new machine, then, which has been doing its wonderful
work for a few days only, is to reproduce artificially chenille
embroidered on light tissues, by mechanically cutting out and gluing
small circles of velvet upon these fabrics.

For this purpose all kinds of velvet may be employed, and, in order to
facilitate the cutting, they are previously coated on the reverse side
with any glue or gum whatever, which gives the velvet a stiffness
favorable to the action of the punch. To effect the object desired the
apparatus has three successive operations to perform: first, cutting the
circles; second, moistening; and third, fastening down the dots upon the
tissue according to a definite order and spacing. The machine may be
constructed upon any scale whatever, although at present it is only made
for operating on pieces 31 inches wide, that being the normal width of
dotted tulles. The quincuncial arrangement of the dots is effected by
the punching, moistening, and fastening down of odd and even dots,
combined with the forward movement of the tissue to be chenilled.

The principal part of the machine is the cam-shaft, A (Figs. 1, 2, and
3), which revolves in the direction of the arrows and passes in the
center of 80 cam-wheels, 40 of which are odd and 40 even, alternately
opposed to each other. This shaft actuates, through its two extremities,
the different combined motions in view of the final object to be
attained, and also carries the motive pulleys, PP'. Figs. 1 and 2 show
the profile of two of these opposed cam-wheels--the arrangement by means
of which two rows of dots (odd and even) are laid down upon the tissue
during one revolution of the shaft or drum, A. Each of the wheels
carries three cams (Figs. 1 and 3), the first, (_a_), corresponding to
the punching; the second, (_a'_), to the moistening, and the third,
(_a''_), to the gluing down of the dots.

The annexed figure, one-quarter actual size, shows in section the
details of the cutting mechanism. To each cam-wheel there corresponds
one punch, and the eighty punches are arranged side by side and parallel
upon a shaft, B, a spring, _b_, holding them constantly against the
circumference of the cam-wheels. In Fig. 2 only one of these details is
shown. The punching arrangement consists of an ordinary punch, _c_, of
variable diameter, screwed to the extremity of a tube, _d_, which is
itself suspended from the end of the lever, _p_, but which can receive
from it at the desired moment the pressure necessary to effect the
cutting. The vertical position of these multiple tubes is insured by
a guide, _e_, which is thoroughly indispensable. Through each of the
tubes, _d_, there passes a plunger designed for expelling from the punch
the piece that has been cut out of the velvet, and for gluing it down to
the fabric. The two small springs, _b'_ and _b''_, tend continually to
lift the tubes as well as the plunger. The whole mechanism is affixed to
solid cast-iron frames, and the machine itself may be mounted on wooden
supports or a metal frame.

The punching is effected on a bronze straight-edge, C, which slides in a
cast-iron channel, D. This presents alternately, in its movement, entire
and punctured spaces, the former for receiving the blow of the punch and
the latter for allowing passage at the desired moment to the plunger
as it goes to fasten the dots upon the tulle which is passing along
underneath the channel, D. The punching is done primarily and
principally by pressure, but, in order to facilitate the complete
detachment of filaments which might retain the punched-out piece, the
punch is likewise given at the same time a slight rotary motion, thus
imitating mechanically what is performed by hand in the maneuver of all
punches. This rotary motion is communicated to the punches by means of
levers actuated by an eccentric, E, and which move the frame, _h_, whose
bars engage with the horizontal lever, _g_, soldered to the tube, _d_,
thus causing the latter at the very moment the punch descends to revolve
from right to left. The forty punches in operation cause the frame to
return to its initial position through the action of the springs, _b'_.
We say forty, since the inventor, in principle, has admitted 80 punches,
operating 40 as odd and 40 as even; obtaining in this way a dotting in
a regular quincunx of one yard, that is to say, 80 dots arranged in two
rows on a fabric 31 inches wide. But it is evident that a much larger
quincunx may be had by putting in play only a half, a third, or a
fourth of the punches, and causing the tulle and velvet to advance
proportionally. For this purpose it is only necessary to unscrew the
punches which are not to act, and to substitute for the ratchet wheel
which controls the unrolling of the I tulle, another having a number of
teeth proportioned to the desired spacing of the dots.

The punching having been executed, and the drum, A, continuing to
revolve, the punches rise a little owing to the conformation of the
cam-wheel, and through the action of the springs, _b_, and allow the
moistener to move forward to dampen the little circles which remain at
the orifice of the punches. The moistener or dampener is a sort of pad
equal in length to the field of action of the punches, and is affixed
to a cross-bar, F, which is connected at its two extremities with the
levers, G, that are actuated by the cam-wheels, H. These cam-wheels, or
eccentrics, H, which are mounted on the shaft of the drum, A, cause the
moistener to move forward as soon as the punches rise after operating,
and, when it arrives beneath the punches, the larger cams, _a_, of
the cam-wheels, A, press the latter upon the pad and thus effect the
dampening of the circles of velvet.

Immediately afterwards, the same eccentrics, H, acting on a lever, I,
uncover the holes in the straight-edge, C, and the channel, D. The
large cams, _a"_, of the wheel, A, then acting very powerfully upon the
respective punches, cause these latter to pass through the orifices so
that the extremity of each punch comes within about one twenty-fifth of
an inch of the fabric to be dotted. In this passage of the tube, _d_, a
small rod, _i_, connected by a lever with the plunger, _f_, is made to
abut against the guide, _e_, thus causing the descent of the plunger to
a sufficient degree to push the velvet "dot" out of the tube and to glue
it upon the fabric. The manner in which these operations are performed
being now well enough understood, let us for a moment examine the
motions of the fabrics to be cut and dotted--the first being velvet or
any other material, even metal (goldleaf, for example), and the second,
the tulle.

The latter has but one motion, and that is in the direction of its
length, while the velvet has, in addition to this same motion, another
slight one from right to left in the direction of its width in order to
diminish waste as much as possible.

The tulle to be dotted is first wound around a roller, R, from whence it
passes over the glass guide-roller, R', and between the channel, D, and
the table, T, to the roller, R", which is heated by steam.

The hot air which is radiated dries the dots, and from thence the fabric
is taken up by other rollers or by any other method. The steam roller,
R", carries at one of its extremities a ratchet wheel whose teeth vary
in number according to the greater or less rapidity with which the tulle
is unrolled. It is actuated by a lever which receives its motion from
the eccentric, K.

[Illustration: IMPROVED MACHINE FOR DOTTING TULLAND OTHER LIGHT
FABRICS.]

In the table, T, there is a rectangular receptacle, _t_, containing
rasped or powdered velvet for the purpose of forming a reverse of the
dot. This powder attaches itself to the gum and imitates on the wrong
side of the fabric a dot similar to that on the upper or right side. The
velvet is wound upon the roller, _r_, and from thence passes under the
guiding roller, _r'_, the punches, and the second roller, _r"_. These
two latter rollers are solidly connected by a straight-edge fixed at the
extremity of the lever, L, whose other end is in continuous correlation
with the eccentric, M, which controls the lateral displacements;
while the eccentric, O, actuates, by means of the screw, Q, and the
ratchet-wheel, S, the longitudinal advance of the velvet. The eccentric,
M, is fixed upon an axle, A', which carries a wheel, U, having teeth
inclined with respect to its axis, and which derives its motion from the
Archimedean screw, N, fixed at one of the extremities of the cam-shaft,
A.

We have stated above that the maximum daily hand production of tulle
dotted in quincunxes of 0.04 of an inch is about one yard. At the rate
of 30 revolutions per minute, and for the same article as that just
mentioned, this dotting machine is capable of producing, theoretically,
360 yards per 10 hours; but practically this production is reduced to
about 250 yards, which, however, is sufficiently satisfactory.

* * * * *

THE REPRODUCTION AND MULTIPLICATION OF NEGATIVES.

By ERNEST EDWARDS, B.A.

A question, relative to the subject of reproducing negatives, which was
put at a meeting of one of your New York societies, prompts me to make a
few remarks on the subject.

Among the numerous and widely diversified ramifications of our business
(the Heliotype Printing Company) we have very often to reproduce and
multiply negatives in both a direct and reversed form. Various methods
for doing this have been tried, and I may here say that I am quite well
aware of all the methods that have hitherto been suggested for the
purpose, but that which I am to describe is the one to which preference
has been given, and which is that known as the carbon process.

A sheet of carbonized paper or "tissue," having been sensitized by
immersion in a bath of bichromate of potash, is dried in the dark and
placed away for future use, although it is undesirable that it be kept
for more than four or five days. This is placed in a printing frame in
contact with the negative and exposed for a few minutes, after which it
is immersed in water, squeegeed down upon a glass plate, and developed
with warm water in the way so well known to carbon printers. The result
is a transparency which, owing to having received a sufficient exposure,
should show every detail of the negative. The nature of the tissue
employed for such a purpose must be such as to give no strong contrasts,
but everything reproduced with soft and fine gradation of tone.

The transparency thus obtained forms the _cliche_ by which the negatives
are subsequently made; and a negative of any size may be obtained by
the camera on wet or dry plates. The transparency must, of course, be
pointed to the sky and the light transmitted through it, no other light
being allowed to reach the lens except that which passes through the
carbon transparency. Care must also be taken that the transparency is
_uniformly_ lighted. If it is not possible to obtain a northern light,
which is best, a reflector of white paper or card may be used which must
be sufficiently large and placed at an angle of about forty-five degrees
to the transparency.

If the repeated negative is to be of the same size as the original it
may be readily produced by repeating the operation of printing on carbon
tissue, using the transparency in place of the negative, or using a dry
plate in place of the tissue. But on the whole I have satisfied myself
that the best results are to be obtained by the first method. There is
a greater softness in the latter method, but a greater character and
similarity to the original in the former method. There is no doubt that
the use of the carbon transparency removes the hardness and riffidness
of the outlines peculiar to the older method of a collodion
transparency, while with carbon as the medium it is difficult for
any but the most experienced eye to distinguish the copy from the
original.--_Photo Times._

* * * * *

A NEW METHOD OF MAKING GELATINE EMULSION.

Since gelatine emulsion first came into use one of the greatest troubles
in connection with the manufacture of it has been that of washing.
According to the first methods the time taken for this part of the
process was, I believe, about twenty-four hours. It was very much
reduced and the ease of manufacture greatly facilitated by the methods
now most generally used, and which were, I believe, first communicated
by Messrs. Wratten and Wainright. I refer to those of precipitating with
alcohol and of straining the emulsion, when set, through canvas, so
as to divide it very finely. When the latter method is resorted to a
comparatively short time is sufficient to wash it. This method, although
a great improvement upon the older ones, yet leaves much to be desired,
especially for those who are not in the habit of making emulsion
regularly, but only an occasional batch. When the weather is at all warm
it takes a long time for the emulsion to set, unless ice be used, and
when once it is set the washing process is an exceedingly "messy" one
unless the water be cooled with ice; and the amount of water taken up
during washing is often so great that there is considerable difficulty
in getting the emulsion to set on the plates. In fact, even in cold
weather, it is not an easy process to conduct in the necessary near
approach to total darkness.

Considerable suspicion has of late been thrown upon the thoroughness of
the alcohol method, unless the emulsion has, previous to precipitation,
been freed of the greater part of the soluble salts by washing; that is
to say, it is doubtful whether the whole of the soluble salts can be
eliminated by the process, and, therefore, unless in exceptionally hot
weather, it would seem best not to trust to it, except as a further
security against soluble bromide and nitrate after washing. Besides
this, the consumption of alcohol is very large. Almost three times the
amount of the emulsion precipitated is required, and this, even when
methylated spirit is used, adds considerably to the expense. With a view
of doing away with the washing altogether, or, rather, of washing of
the silver bromide when not incorporated with the gelatine, several
processes have been invented. By these silver bromide is obtained in a
very fine state of division, ready to mix with gelatine and water in any
proportion.

The best known of them is Captain Abney's very ingenious glycerine
method, which seems to have been thoroughly successful in his hands,
although it has not been in every one's. The silver bromide obtained by
his process is not highly sensitive, and requires boiling with gelatine
before it is in a fit state to make a rapid plate.

We have lately had described in these columns a method of obtaining
bromide in a highly-sensitive state by means of the use of an acid,
whereby, after emulsifying and boiling, the viscosity of the gelatine
was destroyed, and the bromide in time deposited itself. During the late
hot weather, when washing became almost impossible, I was led to cast
about for some method of eliminating the soluble salts less tedious and
"sloppy" than that of washing, more certain and less expensive than that
of precipitating the whole of gelatine with alcohol, and which would
take less time than the method of obtaining the bromide in a pure form.

My first idea was to make up the solutions used in emulsifying in a very
concentrated form, and, after emulsifying, boiling, and allowing to
cool, to add to the thin emulsion thus obtained gelatine to the amount
of twenty grains to the ounce, and to precipitate this with alcohol,
the rest of the gelatine required to make up the bulk being afterwards
added, and the whole thoroughly incorporated by warming and shaking.
I was thus successful in reducing the amount of alcohol required to
one-third of what would be necessary if the whole of the emulsion were
precipitated; but still I found that, if a reliable emulsion were
required, the pellicle as formed had to be washed to free it from the
last trace of soluble salts.

It now struck me that it might be possible to precipitate the bromide of
silver direct from a very weak solution of gelatine, and obtain it in
such a form that it might be filtered, washed, and in every way treated
as an ordinary precipitate. I tried the following experiment. I took--

1. Silver nitrate....................... 200 grains
Water............................... 11/2 ounce.
2. Ammonia bromide...................... 120 grains.
Water................................ 11/2 ounce.
Gelatine............................. 12 grains.

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