336 
AMERICAN AGRICULTURIST. 
[September, 
In Vermont, in which State anil in New Hampshire 
this business is somewhat extensively carried on. 
Potatoes contain variable quantities of starch, or 
from 17 to 24 per cent, according to their specific 
gravity, or heaviness and solidity. This is a very 
important consideration, for the difference, amount¬ 
ing to nearly 50 per cent upon the least quantity 
contained, is sufficient to make the business profit¬ 
able or otherwise. It is clear, therefore, that only 
the best grown crops, and those varieties with solid 
flesh, cau be profitably used in the starch factory. 
Potatoes of a specific gravity of 1.09, (which means 
that a bulk of potatoes equal with a quantity of 
water that weighs 100 lbs., will weigh 109 lbs.,) 
have been found to contain 16 to 17 parts of starch, 
while those of a specific gravity of 1.123 have con¬ 
tained from 24 to 25 
per cent. The amount 
of starch also varies 
with the season, and 
the character of the 
cultivation given to 
the crop, for imma¬ 
ture tubers, or those 
that have been ex¬ 
posed to the light, 
contain much less 
starch than those 
fully ripe, well grown, 
and free from dis¬ 
ease, the difference 
sometimes amount¬ 
ing to one-third. In 
this, as in all other 
instances, the fruits 
of labor are better 
and more profitable as the labor has been well 
or skillfully applied. As soon as the potato is per¬ 
fectly mature, it is richest in starch, and after that 
moment the amount of starch becomes less, more 
especially if germination of the eyes or buds com¬ 
mences ; freezing destroys the starch altogether. 
The building needed for a starch factory may be 
as plain and cheap as is consistent with the proper 
shelter and accommodation of the machinery, the 
necessary storage of potatoes during the working 
season, and the care of the finished product. But 
little expense need be incurred in this direction, 
further than to make the building strong enough 
and water tight. As a large quantity of water is 
needed in the process, a good water-power, which 
will supply both motion and water for washing, is 
most convenient. As a rule the potatoes grown by 
the farmers near the factory, are sold at a stated 
price, and delivered as they may be required 
through the season. From what has been stated 
already, it is evidently to the interest of the careful 
farmer who grows the best potatoes, to sell his crop 
by weight, and greatly to the interest of the manu¬ 
facturer to procure only the heaviest potatoes. 
The first process is washing the potatoes. This 
is done in the washer 
seen at figure 1. The 
potatoes are put into 
the washer at A, pass¬ 
ing through the fun¬ 
nel-shaped tube B , 
which is placed in a 
box or trough C, half 
of which only is 
shown. The potatoes 
are exposed to a 
stream of water as 
they pass through 
the washer and out 
of the smaller end, 
from which they are 
raked by a revolving 
rake B, into the open¬ 
ing E , falling into the 
grater shown in figures 2,3, and 5. The potatoes are 
reduced to pulp by the grater A, fig. 2, a disc of per¬ 
forated sheet iron, which revolves rapidly on the 
shaft B, in a strong curb, C. The potatoes are held 
against the grater by the stationary arms B, and 
the grated pulp falling into the tin box E, fixed 
around the edge of the grater A, is discharged at 
A 1 into the sieve G, fig. 3. A sheet of water falls 
into this sieve from H, and a shower or sprinkling 
from J, the sieve being constantly shaken by the 
rod J. The consequent washing of the pulp sepa¬ 
rates the starch granules from their enclosing cells, 
which are broken up by the grater, and the granules 
being smaller than the fragments of the cells, fall 
through the sieve, while the refuse is discharged at 
K as waste. Potato starch differs from all other 
kinds of starch, both in the size of the granules 
and in their shape. A thin slice of potato placed 
beneath a good microscope, appears as shown at 
figure 4, in which are seen the 
cells packed full of starch gran¬ 
ules of different sizes, the largest 
of theifl being l-300tli part of an 
inch in length. The granules 
are shaped much like a shell 
having lines drawn irregularly 
around a point, as seen at a in the. 
figure. It is very easy to distiiv 
guish potato starch from all* 
other kinds by the aid of a good 
microscope, and it is also easy to 
understand by this illustration 
how the process of grating and 
washing breaks and tears apart 
the walls of the cells, and re¬ 
leases and separates the starch 
from the cellular matter of the 
potato. At L, fig. 3, is shown a 
portion of the grater, with its half cover, JI, raised. 
At fig. 5 is given a ground plan of the washer, gra¬ 
ter, and sieve ; the washer and trough at A, the 
gearing at B, the crank which moves the sieve at 
( 7 , the grater at 1 ), the sieve at E, the box from 
which the sheet of water escapes at F, the sprink¬ 
ler at G, and the dotted line H shows the position 
of the cistern into which the starch falls and is kept 
constantly stirred by means of an agitator shown 
at figure 6. The mixed starch and water is pump¬ 
ed into large vats /, 7, on the same floor as the 
washers, in which it is left to settle during the 
night. After the starch has subsided, the water is 
drawn off by siphons to within 2 feet of*the bot¬ 
tom of each vat. The remainder is stirred and 
Fig. 4. —CELLS OF POTATO AND STARCH GRAINS. 
pumped into smaller vats, A, A, A, fig. 7, in which 
it is again stirred, and again left to settle for six 
hours or more, when the water is drawn off as be¬ 
fore by siphons. The still impure starch left, called 
“grains,” is removed to larger vats, again washed, 
stirred, and settled, and the purification is still 
again repeated until perfect, when the pure starch 
is removed in wheel-barrows to the kiln, fig. 8, to 
be dried. In the kiln there are three racks, A, 
A, A ; the wet starch being placed on the highest 
one, is stirred, and as it dries falls through the 
openings on to the one below, from which it falls 
to the lowest one, and from that on to the bot¬ 
tom of the drying chamber, B, from which it is 
gathered up and packed into barrels. Sometimes 
the starch is dried in solid masses, in which it un- 
dergoes a sort of crystallization, and falls into 
those well known shapes in which it is offered for 
sale for laundry purposes. A ground plan of the 
kiln is shown at figure 9; the shelves are seen at 
A, A; the alley ways, 5 feet wide, at B, B; the 
walls are lathed and plastered, and 18 feet apart; 
the doors of the kiln are shown at B; the furnace, 
C, is simply a large box stove, enclosed for safety 
within brick walls, as seen at figure 10. The 
furnace is in the basement of the factory-, and 
the brick casing opens iuto the floor above, 
where the drying chamber and racks are placed, 
as seen at figure 9, F being the chimney and E 
the brick-wall. There is no simpler manufacture 
than that of starch, the process being solely the 
breaking up of the cells of the potato by grating, 
and the separation of the starch, which is insoluble 
in cold water, from the cellular substance by wash¬ 
ing, and finally the drying and packing of the starch 
for markot. The starch of the potato is used for 
food as well as far the well known purposes of the 
laundry, and frequently appears in the shops as the 
West India arrowroot, which is a kind of starch 
made from the root of a plant known as Maranta 
arundinacca , and for which it is substituted. 
Potato stai'ch is also used as an adulterant in the 
manufacture of cocoa and chocolate, but however 
used, the peculiar shape of the granules leads to 
its easy detection. The waste of the starch manu¬ 
facture contains all the fertilizing matter that has 
been derived from the soil or the manure, such as 
nitrogen, potash, and phosphoric acid, and is well 
Fig. 3 — SIEVE FOR SEPARATING THE STARCH. 
Fig. 5.— PLAN OF THE WASHER. 
