Scientific American Supplement, No. 303

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The first step in advance was the introduction of a machine to purify
middlings. It was found that the flour made from these purified
middlings was whiter than the flour from the first grinding and brought
a better price than even winter wheat flours. Then the aim was to make
as many middlings as possible. To do this and still clean the bran so
as to make a reasonable yield the dress of the burrs was more carefully
attended to, the old fashioned cracks were left out, the faces and
furrows made smooth, true, and uniform, self-adjusting drivers
introduced, and the driving gear better fitted. Spring wheat patents
rapidly rose to the first place in the market, and winter wheat millers
waked up to find their vantage ground occupied by their hitherto
contemned rivals. To their credit it may be said that they have not
been slow in taking up the gauntlet, and through the competition of the
millers of the two climatically divided sections of this country with
each other and among themselves the onward march of milling progress has
been constantly accelerated. Where it will end no man can tell, and
the chief anxiety of every progressive miller, whether he lives in
Pennsylvania or Minnesota, is not to be left behind in the race.

The millers of the more Eastern winter wheat States have a two-fold
question to solve. First, how to make a flour as good as can be found in
the market, and second, how to meet Western competition, which, through
cheap raw material and discriminating freight rates, is making serious
inroads upon the local markets. Whether the latter trouble can be
remedied by legislature, either State or national, or not, remains to be
proven by actual trial. That you can solve the first part of the problem
satisfactorily to yourselves depends upon your readiness to adopt new
ideas and the means you have at hand to carry them out. It is manifestly
impossible to make as good a flour out of soft starchy wheat as out of
that which is harder and more glutinous. It is equally impossible for
the small mill poorly provided with machinery to cope successfully
with the large merchant mill fully equipped with every appliance that
American ingenuity can suggest and money can buy. I believe, however,
that a mill of moderate size can make flour equally as good as the large
mill, though, perhaps, not as economically in regard to yield and cost
of manufacture.

The different methods of milling at present in use may be generally
divided into three distinct processes, which, for want of any better
names, I will distinguish as old style, new process, and gradual
reduction. Perhaps the German division of low milling, half high
milling, and high milling is better. Old style milling was that in
general use in this country up to 1870, and which is still followed in
the great majority of small custom or grist mills. It is very simple,
consisting of grinding the wheat as fine as possible at the first
grinding, and separating the meal into flour, superfine or extra,
middlings, shorts, and bran. Given a pair of millstones and reel long
enough, and the wheat could be made into flour by passing through the
two. Because spring wheat was so poorly adapted to this crude process,
it had to be improved and elaborated, resulting in the new process.

At first this merely consisted of purifying and regrinding the middlings
made in the old way. In its perfected state it may be said to be halfway
between the old style and gradual reduction, and is in use now in many
mills. In it mill stones are used to make the reductions which are only
two in number, in the first of which the aim of the miller is to make as
many middlings as he can while cleaning the bran reasonably well, and
in the second to make the purified middlings into flour. In the most
advanced mills which use the new process, the bran is reground and the
tailings from the coarse middlings, containing germ and large middlings
with pieces of bran attached, are crushed between two rolls. These
can hardly be counted as reductions, as they are simply the finishing
touches, put on to aid in working the stuff up clean and to permit of
a little higher grinding at first. Regarding both old style and new
process milling, you are already posted. Gradual reduction is newer,
much more extensive, and merits a much more thorough explanation. Before
entering upon this I will call your attention to one or two points which
every miller should understand.

The two essential qualities of a good marketable flour are color and
strength. It should be sharply granular and not feel flat and soft to
the touch. A wheat which has an abundance of starch, but is poor in
gluten, cannot make a strong flour. This is the trouble with all soft
wheats, both winter and spring. A wheat which is rich in gluten is hard,
and in the case of our hard Minnesota wheat has a very tender bran.
It is comparatively easy to make a strong flour, but it requires very
careful milling to make a flour of good color from it. Probably the
wheat which combines the most desirable qualities for flour-making
purposes is the red Mediterranean, which has plenty of gluten and a
tough bran, though claimed by some to have a little too much coloring
matter, while the body of the berry is white. By poor milling a good
wheat can be made into flour deficient both in strength and color, and
by careful milling a wheat naturally deficient in strength may be made
into flour having all the strength there was in the wheat originally and
of good color. Good milling is indispensable, no matter what the quality
of the wheat may be.

The idea of gradual reduction milling was borrowed by our millers from
the Hungarian mills. There is, however, this difference between the
Hungarian system and gradual reduction, as applied in this country, that
in the former, when fully carried out, the products of the different
breaks are kept separate to the end, and a large number of different
grades of flour made, while in the system, as applied in this country,
the separations are combined at different stages and usually only three
different grades of flour made, viz.: patent, baker's, or as it is
termed in Minnesota, clear flour, and low grade or red dog. In the
largest mills the patent is often subdivided into first and second, and
they may make different grades of baker's flour, these mills approaching
much nearer to the Hungarian system, though modifying it to American
methods and machinery. In mills of from three to five hundred barrels
daily capacity, it is hardly possible or profitable to go to this
subdivision of grades, owing to the excessive amount of machinery
necessary to handling the stuff in its different stages of completion.
The Hungarian system has, therefore, been greatly modified by American
millers and milling engineers to adapt it to the requirements of mills
of average capacity. This modified Hungarian system we call gradual
reduction. It can be profitably employed in any mill large enough to run
at all on merchant work. So far it has not been found practicable to use
it in mills of less than one hundred and twenty-five to one hundred and
fifty barrels capacity in twenty-four hours, and it is better to have
the mill of at least double this capacity.

Gradual reduction, as its name implies, consists in reducing the
wheat to flour, shorts, and bran, by several successive operations or
reductions technically called breaks, the process going on gradually,
each break leaving the material a little finer than the preceding one.
Usually five reductions or breaks are made, though six or seven may be
used. The larger the number of breaks the more complicated the system
becomes, and it is preferable to keep it as simple as possible, for even
at its simplest it requires a good, wide-awake thinking miller to handle
it successfully. When it is thoroughly and systematically carried out in
the mill it is without question as much in advance of the new process as
that is ahead of the old style of milling.

In order that I may convey to you as clear an idea of gradual milling
reduction as possible, I will give as fully as possible the programme of
a mill of one hundred and fifty barrels maximum daily capacity designed
to work on mixed hard and soft spring wheat, and which probably will
come much nearer to meeting the conditions under which you have to mill
than any other I have found readily obtainable. I have chosen a mill of
this size, first, because following out the programme of a larger one
would require too much time and too great a repetition of details and
not give you any clearer idea of the main principles involved, and
secondly, because I thought it would come nearer meeting the average
requirements of the members of your association. Your worthy secretary
cautioned me that I must remember that I was going to talk to winter
wheat millers. The main principles and methods of gradual reduction are
the same, whether applied to spring or winter wheat; the details may
have to be varied to suit the varying conditions under which different
mills are operated. For this programme I am indebted to Mr. James Pye,
of Minneapolis, who is rapidly gaining an enviable and well deserved
reputation as a milling engineer, and one who has given much study to
the practical planning and working of gradual reduction mills.

And right here let me say that no miller should undertake to build
a gradual reduction mill, or to change over his mill to the gradual
reduction system, until he has consulted with some good milling engineer
(the term millwright means very little nowadays), and obtained from him
a programme which shall fit the size of the mill, the stock upon which
it has to work, and the grade of flour which it is to make. This
programme is to the miller what a chart is to the sailor. It shows him
the course he must pursue, how the stuff must be handled, and where it
must go. Without it he will be "going it blind," or at best only feeling
his way in the dark. A gradual reduction mill, to be successful, must
have a well-defined system, and to have this system, the miller must
have a definite plan to work by. But to go on with my programme.

The wheat is first cleaned as thoroughly as possible to remove all
extraneous impurities. In the cleaning operations care should be taken
to scratch or abrade the bran as little as possible, for this reason:
The outer coating of the bran is hard and more or less friable. Wherever
it is scratched a portion is liable to become finely comminuted in the
subsequent reductions, so finely that it is impossible to separate it
from the flour by bolting, and consequently the grade of the latter is
lowered. The ultimate purpose of the miller being to separate the flour
portion of the berry from dirt, germ, and bran it is important that he
does not at any stage of the process get any dirt or fine bran speck or
dust mixed in with his flour, for if he does he cannot get rid of it
again. So it must be borne in mind that at all stages of flouring, any
abrasion or comminution of the bran is to be avoided as far as possible.

After the wheat is cleaned, it is by the first break or reduction split
or cut open, in order to liberate the germ and crease impurities. As
whatever of dirt is liberated by this break becomes mixed in with the
flour, it is desirable to keep the amount of the latter as small as
possible. Indeed, in all the reductions the object is to make as little
flour and as many middlings as possible, for the reason that the latter
can be purified, while the former cannot, at least by any means at
present in use. After the first break the cracked wheat goes to a
scalping reel covered with No. 22 wire cloth. The flour, middlings,
etc., go through the cloth, and the cracked wheat goes over the tail of
the reel to the second machine, which breaks it still finer. After this
break the flour and middlings are scalped out on a reel covered with
No. 22 wire cloth. The tailings go to the third machine, and are still
further reduced, then through a reel covered with No. 24 wire cloth. The
tailings go to the fourth machine, which makes them still finer, then
through a fourth scalping reel the same as the third. The tailings from
this reel are mostly bran with some middlings adhering, and go to the
fifth machine, which cleans the bran. From this break the material
passes to a reel covered with bolting cloth varying in fineness from No.
10 at the head to No. 00 at the tail. What goes over the tail of this
reel is sent to the bran bin, and that which goes through next to the
tail of the reel, goes to the shorts bin. The middlings from this reel
go to a middlings purifier, which I will call No. 1, or bran middlings
purifier. The flour which comes from this reel is sent to the chop reel
covered at the head with say No. 9, with about No. 5 in the middle and
No 0 at the tail. You will remember that after each reduction the flour
and middlings were taken out by the scalping reels. This chop, as it is
now called, also goes to the same reel I have just mentioned. The
coarse middlings which go over the tail of this reel go to a middlings
purifier, which I will designate as No. 2. These go through the No. 0
cloth at the tail of the reel purifier No. 3; those which go through No.
5 cloth got to purifier No. 4; while all that goes through the No. 9
cloth at the head of the reel is dropped to a second reel clothed with
Nos. 13 to 15 cloth with two feet of No. 10 at the tail. The flour from
this reel goes to the baker's flour packer; that which drops through the
No. 10 is sent to the middlings stone, while that which goes over the
tail of the reel goes to purifier No. 4. We have now disposed of all the
immediate products of the first five breaks, tracing them successively
to the bran and shorts bins, to the baker's flour packer and to the
middlings purifiers, a very small portion going to the middlings stone
without going through the purifiers.

The middlings are handled as follows in the purifiers. From the No. 1
machine, which takes the middlings from the fifth break, the tailings go
to the shorts bin, the middlings which are sufficiently well purified go
to the middlings stone, while those from near the tail of the machine
which contain a little germ and bran specks go to the second germ rolls,
these being a pair of smooth rolls which flatten out the germ and crush
the middlings, loosening adhering particles from the bran specks. From
the second germ rolls the material goes to a reel, where it is separated
into flour which goes into the baker's grade, fine middlings which are
returned to the second germ rolls at once, some still coarser which go
to a pair of finely corrugated iron rolls for red dog, and what goes
over the tail of the reel goes to the shorts bin. The No. 2 purifier
takes the coarse middlings from the tail of the first or chop reel as
already stated. The tailings from this machine go to the shorts bin,
some few middlings from next the tail of the machine are returned to the
head of the same machine, while the remainder are sent to the first germ
rolls. The reason for returning is more to enable the miller to keep a
regular feed on the purifiers than otherwise. The No. 3 purifier takes
the middlings from the 0 cloth on the chop reel. From purifier No. 3
they drop to purifier No. 5. A small portion that are not sufficiently
well purified are returned to the head of No. 3, while those from the
head of the machine, which are well purified, are sent to the middlings
stones. The remainder, which contain a great deal of the germ, are taken
to the first germ rolls, in passing which they are crushed lightly to
flatten the germ without making any more flour than necessary. The No. 4
purifier takes the middlings from No. 2 and also from No. 5 cloth on
the chop reel and from the No. 10 on the tail of the baker's reel. The
middlings from the head of this machine go to the middlings stones, and
the remainder to purifier No. 6. The tailings from Nos. 3, 4, 5, and 6
go to the red dog rolls. A small portion not sufficiently well purified
are returned from No. 6 to the head of No. 4, while the cleaned
middlings go to the middlings stones.

The portions of the material which have not been traced either to the
baker's flour or the bran and shorts bins are the middlings which have
gone to the middlings stones, the germy middlings which have gone to the
first germ rolls, and the tailings from purifiers Nos. 3, 4, 5, and 6,
and some little stuff not quite poor enough for shorts from the reel
following the second germ rolls. Taking these _seriatim_: the middlings
after passing through the middlings stones, go to the first patent reel
covered with eleven feet of No. 13 and four feet of No. 8. The flour
from the head of the reel goes to the patent packer, that from the
remainder of the reel is dropped to another reel, while the tailings go
to the No. 4 purifier. The lower patent reel is clothed with No. 14 and
two feet of No. 10 cloth; from the head of the reel the flour goes to
the patent packer, the remainder that passes through the No. 10 cloth
which will not do to go into the patent, being returned to the middlings
stones, while the tailings are sent to the No. 4 purifier.

The germ middlings, after being slightly crushed as before stated, are
sent to a reel covered with five feet of No. 13 cloth, five feet of No.
14, and the balance with cloth varying in coarseness from No. 7 to No.
00. The flour from this reel goes into the patent, the tailings to the
red dog rolls, the middlings from next the tail of the reel which still
contain some germ to the second germ rolls, while the middlings which
are free from germ go to the middlings stones.

The tailings from purifiers 3, 4, 5, and 6, the material from the reel
following the second germ rolls, which is too good for shorts, but not
good enough to be returned into middlings again, and the tailings from
the reel following the first germ rolls are sent to the red dog rolls,
which, as I have stated, are finely corrugated. Following these rolls is
the red dog reel. The flour goes to the red dog bin, the tailings to
the shorts bin, while some stuff intermediate between the two, not fine
enough for the flour but too good for shorts, is returned to the red dog
rolls.

This finishes the programme. I have not given it as one which is exactly
suited to winter wheat milling. However, as I said before, the general
principles are the same in either winter or wheat gradual reduction
mills, and the various systems of gradual reduction, although they
differ in many points, and although there are probably no two engineers
who would agree as to all the details of a programme, the main ideas
are essentially the same. The system has been well described as one of
gradual and continued purification. In the programme above given the
idea was to fit up a mill which should do a maximum amount of work of
good quality with a minimum amount of expenditure and machinery. In a
larger mill or even in a mill of the same capacity where money was not
an object, the various separations would probably be handled a little
differently, the flour and middlings from the first and fifth breaks
being handled together, and those from the second, third, and fourth
breaks being also handled together. The reason for this separation being
that the flour from the first and fifth breaks contain, the first a
great deal of crease dirt, and the fifth more bran dust than that from
the other breaks, the result being a lower grade of flour. The object
all along being to keep the amount of flour with which dirt can get
mixed as small as possible, and not to lower the grade of any part of
the product by mixing it with that which is inferior, always bearing in
mind that the aim is to make as many middlings as possible, for they can
be purified while the flour can not, and that whenever any dirt is once
eliminated it should be kept out afterwards. This leads me to say that
if a miller thinks the adoption of rolls or reduction machines is all
there is of the system, he is very much mistaken. If anything, more of
the success of the mill depends upon the careful handling of the stuff
after the breaks are made, and here the miller who is in earnest to
master the gradual reduction system will find his greatest opportunities
for study and improvement. A few years back it was an axiom of the trade
that the condition of the millstone was the key to successful
milling. This was true because the subsequent process of bolting was
comparatively simple. Now the mere making of the breaks is a small
matter compared with the complex separations which come after. In
the foregoing programme we had five breaks or successive reductions.
Although this is better than a smaller number, I will here say that
it is not absolutely essential, for very good work is done with four
breaks. The mill for which this programme was made, including the
building, cost about $15,000, and is designed to make about sixty per
cent. of patent, thirty-five per cent. of baker's, and five per cent.
of low grade, results which are in advance of many larger and more
pretentious mills.

One difficulty in the way of adapting the gradual reduction system to
mills of very small capacity is that the various machines require to be
loaded to a certain degree in order to work at their best. It is only a
matter of short time when our milling inventors will design machinery
especially for small mills; in fact they are now doing it, and every
day brings it more within the power of the small miller to improve his
manner of milling. To show what can be done in this direction I will
briefly describe a mill of about ninety barrels maximum capacity per
twenty-four hours, which is as small as can be profitably worked. I will
premise this description by saying it is designed with a view to the
greatest economy of cost, the best trade of work, and to reduce the
amount of machinery and the handling of the stuff as much as possible.
This latter point is of much importance in any mill, either large or
small, no matter upon what system it is operated, for it takes power to
run elevators and conveyors, and especially in elevating and conveying
middlings, especially those made from winter wheat, their quality is
inured and a loss incurred, by the unavoidable amount of flour made by
the friction of the particles against each other. So much is this the
case that in one of our largest mills it is deemed preferable to move
the middlings from one end of the mill to the other by means of a hopper
bin on a car which runs on a track spiked to the floor, rather than to
employ a conveyor. A mill built as I am going to describe would require
from fifty to sixty horse-power to run it, and including steam power and
building would cost from $10,000 to $12,000, according to location. I
give it as of interest to those among your number who own small mills
and may contemplate improving them.

The building is four stories high, including basement, and thirty-two
feet square. It would be some better to have it larger, but it is made
this small to show how small a space a mill of this size can be made to
occupy. No story is less than twelve feet high. The machinery Is very
conveniently arranged, and there is plenty of room all around. The
system is a modification of the gradual reduction system, the middlings
being worked upon millstones. The first break is on one pair of 9 x
18 inch corrugated iron rolls, eight corrugations to the inch, the
corrugations running parallel with the axis of the rolls. The second
break on rolls having twelve corrugations to the inch, the third
sixteen, and the fourth twenty to the inch, while the fifth break, where
the bran is finally cleaned, has twenty-four corrugations to the inch.
The basement contains the line shaft and pulleys for driving rolls,
stones, cockle machine, and separator. The only other machinery in the
basement is the cockle machine. The line shaft runs directly through
the center of the basement, the power being from engine or water wheel
outside the building. The first floor has the roller mills in a line
nearly over the line shaft below, the middlings stones, two in number,
at one side opposite the entrance to the mill, the receiving bin at
one side of the entrance in the corner of the mill, and the two flour
packers for the baker's and patent flour in the other corner. This
arrangement leaves over half of the floor area for receiving and packing
purposes. The bolting chests, one with six reel and the other with three
reel begin on the second floor and reach up into the attic. An upright
shaft from the line shaft in the basement geared to a horizontal shaft
running through the attic parallel with the line shaft below, comprise
about all the shafting there is in the mill. There is a short shaft on
the second floor from which the two purifiers on this floor and the two
in the attic are driven, and another short shaft on the first floor to
drive the packers. There are four purifiers, two on the second floor,
and two more directly over them in the attic. The elevator heads are all
directly upon the attic line shaft, and the bolting chests are driven by
uprights dropped from this shaft. The combined smutter and brush machine
is on the third floor at one end of the bolting chests and directly over
the stock hoppers. This comprises all the machinery in the mill. The
programme is about as follows:

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