926 
observed to select only the best grades 
of galvanized wire netting for making 
the racks. If poorer grades are used the 
acids of the fruit are likely to act on 
the metals, producing undesirable re- 
sults. 
Heating Apparatus 
Satisfactory results are so dependent 
upon the heating apparatus that this 
becomes one of the most important fea- 
tures of an evaporator. 
In the smaller types of evaporators, 
where comparatively little is involved 
and the question of fuel does not enter 
seriously into consideration, almost any 
small stove commensurate with the size 
of the particular evaporator in question 
may be used. 
In the larger kiln evaporators the mat- 
ter is a more important one. Formerly, 
ordinary cast-iron stoves were used con- 
siderably, two or more of them frequent- 
ly being required to heat a single kiln, 
but these have largely gone out of use. 
In their stead large furnaces are now 
most commonly used. These are spe- 
cially designed for the purpose and are 
provided with relatively large fire pots, 
correspondingly large ash pits, and large 
radiating surfaces. As it is necessary to 
burn a relatively large quantity of fuel 
in a given time, the size of the grate is 
made with this end in view. For a kiln 
floor 20 feet square, or 400 square feet 
of surface, the grate surface is usually 
about three feet in diameter, containing 
from five to seven square feet. 
As to the most satisfactory length of 
pipe connecting the furnace and chim- 
ney, opinions differ. Perhaps the most 
common method of piping is the follow- 
ing: The furnace, with two flanges for 
attaching the pipe, is placed in the cen- 
ter; the pipe from each flange is then 
extended to the side of the room opposite 
the chimney, and from this point the two 
sections, extending in opposite directions, 
follow the wall, at a distance of two or 
three feet from it, to the chimney. In 
a kiln 20 feet square, some 65 or 70 feet 
are thus required. Ten-inch pipe is a 
common size to use for this purpose. It 
is placed about three feet below the kiln 
floor. 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
Some operators think that a better dis- 
tribution of heat is obtained if the pipes 
extend back and forth, two or three feet 
apart, under the entire floor of the kiln, 
thus requiring 200 feet or more instead 
of the shorter lengih above suggested. 
The greater length, however, is less fre- 
quently used than the smaller. 
In some cases the heat is so intense 
directly over the furnace that the fruit 
dries more rapidly in the center of the 
floor than about the sides. To regulate 
this and make the drying as uniform as 
possible, a “deflector,” consisting of a 
piece of sheet iron or tin several feet 
square, is attached to the floor directly 
above the furnace. 
Open grates, which in effect are fur- 
naces with all parts above the grates 
removed, are used occasionally and are 
recommended by some because they re- 
quire less fuel, less attention to firing, 
and will dry the fruit in a shorter space 
of time. On the other hand, so much 
dust rises from them that they are not 
used in making the best grades of fruit. 
Tower evaporators may be heated by 
the same style of furnaces that are used 
in kiln driers. The size of furnace suffi- 
cient to evaporate a given quantity of 
fruit in a given time is probably about 
the same in either type of evaporator. 
In some respects a steam system is the 
most satisfactory method of heating, but 
it is comparatively little used, possibly 
due to the larger first cost of installing 
such a system. It is especially applicable 
in case of evaporators that are operated 
in connection with some other business 
that requires the use of considerable 
steam power, such as a large cider mill, 
which requires the power for running 
the presses, 
In kiln evaporators the steam pipes 
are generally placed in as close proxim- 
ity to the floor of the drying room as is 
convenient—within a foot or even closer. 
That every steam pipe nearest the floor 
may supply the greatest amount of heat 
it should have its own return to the 
main return of the system. 
One inch pipe is generally used for 
such systems. No very definite data are 
available in regard to the amount neces- 
