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ADHESIVES FOR DILUTE i.,;L T~3jL' i 2 L C RNOLi Jh .-- ,..
IN C HITE L-F :,I,., cE I cr C-.... L T7C-,,, ",
By Chas. F. Henderson and IrviiL, Keiser,
Division of Domestic Plant Quarantines
Cryolite was first used in field operations arai st white-fringed
beetles (Graphognathus spp.) in 1939- Its use made possible control
activities on every know type of infested property, as this insecti-
cide is less injurious than calcium arsenate to leguwidious plants and
to livestock. The cryolite was first applied as a dust, but difficulty
was encountered in keeping an adequate coverage on the plant foliage
because of the frequent rains during the adult eimerr;eice season in the
Gulf coast area where the beetles were found. Various dust adhesives
were tested by the Division of Cereal and Forage Insect Investigations,
but none were found effective. A definite need therefore existed for a
cryolite formulation with adhesive quality which would assure effective
coverage for a much longer period than that afforded by dusts*
In 1940 dilute cryolite sprays with fish oil as the ao yjive agent
were first used against white-fringed beetles. These spra-;c were capa-
ble of maintaining adequate residues after several inches of rainfall,
and their use was extended to all control areas as quickly as equipment
could be provided. Unfortunately, dilute sprays require the application
of approximately 175 gallons of spray liquid per acre, which necessi-
tates heavy equipment and limits their use on cultivated crops. Dust
was still the only practicable means for controlling white-fringed
beetles in cultivated fields.
Because of the limited usefulness of dilute sprays in the over-all
control program, experiments with concentrated sprays were initiated in
Gulfport, Miss., in 1940 by S. F. Potts, of the Division of Forest
Insect Investigationswhile on temporary loan to the Division of Cereal
and Forage Insect Investigations. Two small power atomizers and hand
atomizing apparatus were used for applying the sprays. Cryolite (and
calcium arsenate) applied as concentrated sprays manifested heavier
initial deposits, better adherence to the foliage, and greater ef-
fectiveness in reducing adult beetle populations than when applied as
dilute sprays. Only 5 gallons of finely atomized concentrated spray
appeared to give an adequate coverage, whereas 200 gallons of dilute
spray was necessary.
e/ The writers acknowledge the assistance of L.E. Smith (re-
signe) in the dilute-spray studies, R. Q. Gardenhire (resigned) in
the field tests, end William Breland in the chemical laboratory.
During the fall of 1940 and the spring of 1941, a concentrated-
spray machine suitable for regular control operations was developed.
This consisted essentially of a blower delivering a blast of air
through a h-inch nozzle provided with small jets, through which a
constant flow of spray material was pumped. Later the jets were super-
seded by a conventional potato-spray nozzle, which reduced clogging and
was less expensive. It was not until 1943, however, that the concen-
trated-spray machine was tested extensively in the field. In the mean-
time a definite need existed for a dilute-spray formula with an adhesive
agent other than fish oil. This material was becoming increasingly
difficult to obtain during the war years, was comparatively expensive,
and vwas objectionable for urban use because of its odor. A series of
tests to find a satisfactory substitute for fish oil in dilute cryolite
sprays was therefore initiated.
Laboratory Tests.--A special turntable machine (fig. 1) was de-
vised whereby experimental amounts of each spray formulation could be
applied to waxed glass plates or to plants mounted on the turntable and
then subjected to different amounts of artificial rainfall. By this
method it was possible to select in a comparatively short time those
sprays which appeared most promising from the large number tested.
The waxed plates were prepared by dipping glass slides into a satu-
rated solution of beeswax in carbon tetrachloride and allowing them to
dry. The spray was applied with a specially constructed machine holding
2 gallons of spray liquid, and the pressure was kept constant in all
tests with the necessary pressure gages. Eighteen plates were treated
with each test spray during 15 revolutions of the turntable. The
plates were allowed to dry for 24. hours, and six were then selected at
random for determining initial deposits. Six other plates were sub-
jected to 3 inches of artificial rainfall, and the remainder to 6
inches. The cryolite deposits and residues were determined chemically
by scraping the wax and cryolite from the treated surfaces into a
Claisen flask and quantitatively analyzing the contents for cryolite,
using the Willard and Winter method for fluorine determination.-/
The adhesives tested, together with the amounts that wuld be in-
cluded with 12 pounds of synthetic cryolite (88% sodium fluoaluminate)
in 100 gallons of total spray liquid, were as follows:
Aluminum sulfate 3 lb., lime 1 Ib.
Ferrous sulfate 2 lb., lime ilb.
Zinc sulfate 31 lb., lime 1-L lb.
CM-705 (a byproduct in manufacture of linseed oil) 3 lb.
Washed linseed oil 6 Ib.
Washed linseed oil 6 lb., soda ash 0.15 lb.
Ammonium caseinate 3 lb.
2/ Willard, H. H., and Winter, 0. B. Volumetric method for deter-
mination of fluorine. Indus. and Engin. Chem., Analyt. Ed. 5: 7-10. 1933.
Ammonium rei.;t- F lb#
Cottonseed oil 5 13.
Keltex (sodium ejL'aLe product) I lb.
Kelgin (sodium algilnate prcct) lb.
Spraysoy (soybean productt for agricultural sprays) 3 lb.
Superloid (soybean pro'.-t for agricultural sprays) lb.
When more than one ingredient is listed above (with the exception
of washed linseed oil and soda ash), the two chemicals combine in the
spray tank, forriug a freshly precipitated hydroxide gel, and the
amounts given are based on the stoichiometric combining weights. Soda
ash was added to the washed linseed oil in order that it might react
with the excess acid present in this product and thus prevent floccu-
lation of the cryolite. In each series of tests fish oil was used as
an arbitrary standard at the rate of 3 pounds per 100 gallons of spray.
The following formulations proved most satisfactory from the
standpoint of adhesiveness, cost, and availability of ingredients:
CM-705, aluminum sulfate and lime, ferrous sulfate and lime, and zinc
sulfate and lime. Since the aluminum hydroxide gel formed by the re-
action of aluminum sulfate and lime proved to be so satisfactory, other
salts, such as sodium carbonate and magnesium carbonate, were tested
with aluminum sulfate in the proper stoichiometric amounts to determine
whether or not the gels thus formed would have physical qualities con-
ducive to better adhesiveness in sprays. This was not found to be so.
Field Tests.--Several series of field tests were then conducted in
which each of the promising spray formulations was applied to a 1/10-
acre test plot with a small dilute-spray machine. In each series of
tests gallberry (Ilex glabra L.) foliage was collected franom the field
and chemically an-yzed to determine initial cryolite deposits. From
one to three additional samplings were made thereafter, depending upon
the amount of rainfall and other weather conditions. After the third
series of tests the zinc sulfate-lime spray was eliminated as being
less satisfactory than the other three formulations. The adhesiveness
of the three remaining sprays is shown in table 1. Results with fish
oil are also included for comparative purposes.
On the basis of the mean results, CM-705 was the best adhesive,
followed by aluminum sulfate-lime, fish oil, and ferrous sulfate-lime.
CM-705 was too expensive to justify its use in preference to the alumi-
num sulfate-lime combination, since it was only slightly superior in
retaining cryolite residues. Moreover, when the median was considered
as the statistical criterion, the aluminum sulfate-lime formulation
was better than any of the other three sprays, and the results were
more consistent than those obtained with CM-705. It was therefore
decided to test the cryolite-aluminum sulfate-lime dilute spray in
regular control operations.
Table l.--Loss from initial deposit of dilute cryolite spray containing
various adhesives, Gulfport, Miss., June, July, and August 1944.
Test Rain CM-705 Ferrous t Aluminum
sulfate sulfate Fish oil
and lime and lime '
Inches Percent Percent Percent Percent
1 i -- 57 57 60
2 0.94 19 4o 61
3 1.-34 41 64 62 78
4 .23 13 26 41 50
5 2.29 75 98 82 84
6 .44 52 57 46 45
7 .44 61 68 51 43
8 1.18 82 85 75 77
9 .74 61 79 61 68
10 .92 80 88 73 81
ean-------- 54 69 59 65
Median -------------63 70 59 65
L/ No record.
Control Demonstrations.--Field control demonstrations were con-
ducted in the Gulfport and Hattiesburg areas with regular dilute-spray
machines (fig. 2). In the Gulfport area tests were conducted in two
fields. Half of each field was treated with cryolite spray containing
fish oil as the adhesive agent, and the other half with cryolite spray
containing aluminum sulfate-lime. In each field the aluminum sulfate-
lime combination gave higher adult-beetle mortalities. When the re-
sults of these two tests were combined, 76 percent mortality was ob-
tained with the fish-oil spray and 86 percent with the aluminum sulfate-
lime formulation. In the Hattiesburg area tests were conducted on only
one field, and a higher mortality was also obtained with the cryolite
spray containing the aluminum sulfate-lime adhesive.
In 1943 large-scale field tests were conducted with the concen-
trated-spray machine developed by the Division of Domestic Plant Quaran-
tines (fig. 3). This machine proved to be highly satisfactory for se-
curing adequate adult-beetle mortalities at a cost much below that of
dilute sprays or dusts. The formulation then used was as follows:
Cryolite 50 pounds, 40-percent Aresket (sodium monosulfonate of mono-
butyldiphenyl) 1 quart, raw linseed oil 5 quarts, and water 18 gallons.
Aresket was subsequently superseded by Daxad 11 (sodium salt of
polymerized alkylaryl sulfonic acid.6) ad Daxad l4 (sodium salt of
polymerized alkylaryl sulfonio acids and an inorganic suspending agent),
as the latter products are Loth suspending and wetting agents and mini-
mize settling of the mixture in the con. 6ntrat.ed-sBpray tank,
Because linhseed oil was unavailable at that time, a series of ex-
periments was initiated to develop a concentrated spray with ingredients
comparatively inexpensive and available d-ting the war years. It was
desirable that the spray mixture should be (I) highly fluid, (2) readily
suspended with a minimum of agitation, (3) sufficiently adhesive to
withstand the heavy rainfall characteristic of this area, (4) easily
prepared, and (5) as inexpensive as possible. Fish oil was undesirable
from an over-all standpoint, because of its offensive odor. Further-
more, this adhesive in concentrated sprays .-equired expensive wetting
and suspending agents, which increased +the difficulty of preparation and
the cost of the final spray mixture.
Laboratory Tests.--Since the aluminum hydroxide gel formed by the
reaction of lime with aluminum sulfate was shown to be as adhesive as
fish oil in dilute cryolite spray mixtures, it was believed that this
gel might also constitute a satisfactory adhesive in concentrated sprays
Therefore, a large number of laboratory tests were conducted on the
turntable apparatus with aluminum sulfate in amounts ranging from 2i to
4JL pounds per 50 gallons of total spray, together with lime or sodium
silicate (water glass) in the proper stoichiometric proportions, to
determine which quantity would be most adhesive and still yield a rela-
tively fluid spray. The concentrated spray contained 2 pounds of syn-
thetic cryolite per gallon of total spray liquid. The sprays were ap-
plied with the concentrated-spray machine (as shown in fig. 3) to freshly
picked gallberry foliage placed in small flasks of water and mounted on
the revolving turntable. At first the waxed plates were used, but it
was soon found that electrostatic charges made the comparatively heavy
deposit of cryolite from the concentrated-spray machine adhere to the
waxed surfaces when subjected to artificial rainfall whether or not an
adhesive was included. Therefore, the foliage was substituted for the
waxed plates. After the spray residue on the foliage had been allowed
to dry for 24 hours, a sample consisting of one-third of the foliage
was taken at random for determining the initial cryolite deposit, and
the remaining thirds were subjected to 2 and 4 inches, respectively, of
artificial rainfall applied with a specially constructed apparatus.
These leaves were then chemically analyzed for cryolite residues.
A large number of laboratory tests conducted in this manner indi-
cated that a concentrated spray consisting of synthetic cryolite 100
pounds, aluminum sulfate 5 pounds, sodium silicate 9 pounds, and water
to make 50 gallons was very fluid, easy to resuspend after hours of
settling, and more adhesive than the fish oil spray under the conditions
of these experiments.
Field Tests.-When tested in the field the synthetic cryolite-
aluminum sulfate-sodium silicate spray was found to be totally unsatis-
factory. Upon exposure to natural weathering the gels (aluminum hy-
droxide and silicic acid) formed by the reaction of aluminum sulfate
and sodium silicate became granular upon desiccation, and the spray
deposit was easily removed by irii.d., mechanical shock, an-d especially
rain. This was found to be true also for the altamiinu sulfate-lime
A nondrying mineral oil was added to the aluminum sulfate-sodium
silicate spray to determine whether or not it would delay granulation.
Several different oils were tested, and Straw Oil-3O40, a medium summer
oil, was found to be the most satisfactory as well as the least ex-
pensive. Although this oil was ineffectual in the aluminum sulfate-
water glass spray with synthetic cryolite, it did increase the adhesive-
ness with natural conditioned cryolite. The natural cryolite used in
1945 contained 0.25 percent of condiLtioning agent added by the manu-
facturer. '.hen this product was used in concentrated sprays, Igepal
(a condensation product of ethylene oxide and an alkylated cresol) was
added as a wetting agent.
Because of the low unsulfonatable residue (80 percent) of Straw
Oil-340, it was believed that considerable damage might result from its
use on crop foliage during the summer season. Therefore, foliage-injury
tests were initiated at the Alabama State Prison Farm at Atmore. The
conditioned natural cryolite-Igepal-aluminum sulfate-water glass-Straw
Oil spray and the synthetic cryolite-Daxads 11 and 14-fish oil spray
were applied to the following crops at the rate of 6 gallons (1 quart
of Straw Oil or fish oil) per acre, with the concentrated-spray machine:
Carrots, beets, tomatoes, cotton, black-eyed peas, crowder peas, lima
beans (small and large), and corn (5 to 6 feet tall). No burning of the
foliage resulted, even though the sprays were applied at an air tempera-
ture of 900 F. mid the weather was very hot during the week between
treatments and observations. No injury was noticed even in spots where
an extremely heavy deposit was applied, as at the beginning of a row.
It therefore appeared that Straw Oil-340O was reasonably safe for use on
most crops from a foliage-burn standpoint. The conditioned natural
cryolite-aluminum sulfate-water glass-Igepal-Straw Oil spray was later
used in several control areas without any subsequent plant injury.
This included the frequent spraying of ornamentals in Amite and New
Although this spray mixture was used in several areas with complete
satisfaction, studies were continued for improving the formulation. It
was found that the aluminum sulfate and water glass could be deleted
from the spray mixture, and the new formulation-i.e., conditioned
natural cryolite, Igepal, and Straw Oil-3140--was even more adhesive
than the one including these two ingredients. This new spray was also
extremely fluid and did not settle out in the spray tank even when left
for several days with no agitation. It was also more adhesive and
easier to prepare than the synthetic cryolite-Daxads-fish oil mixture,
and the least expensive of all the spray formulations tested. Further-
more, because of its nonoffensive odor, this spray could be used in
many places where fish oil would be objectionable.
A large-scale field test was conducted at Gulfport, Miss., to com-
pare the most promising spray mixtures selected from the preliminary
testing of 37 spray combinations. Test plots -acre in size were
sprayed with the different formulations on three occasions. Chemical
analyses of gallberry foliage growing naturally on these idle-land plots
were made just prior to each treatment, immediately thereafter, and
after each rainfall of at least -- inch. If there was less than inch
of rainfall for 8 days, samples were collected for that period to de-
termine the effect of this type of weathering on the different spray
deposits. In all tests 2 pounds of cryolite, natural or synthetic, was
conltaixed in each gallon of total spray. These spray mixtures were pre-
pared by running approximately 35 gallons of water into the 50-gallon
spray tank and, with the agitator operating at full speed, adding the
other ingredients, and finally sufficient water to make 50 gallons of
total spray. The results are shown in table 2.
The total precipitation was 4*27 inches during this test. Immedi-
ately afterward there was a rainfall of 5.42 inches spread over a 9-day
period, with 4 inches falling in a single day. A further sampling was
then made from the test plots treated with the three best spray formu-
lations as listed in table 2, and the analyses showed the following re-
ductions in deposits: No. 1, W7 percent; No. 2, 70 percent; and 1o. 3,
84 percent. It is therefore evident that the natural cryolite-Straw Oil
formulation (No. 2) was better than the synthetic cryolite-fish oil
spray (No. 3) even under excessively heavy rainfall. This spray is about
10 percent less expensive than the fish oil spray, and when cost of the
adhesive materials alone is considered, a saving of approximately 70
percent is possible. As noted from table 2, Straw Oil cannot be substi-
tuted for fish oil in the Daxad-synthetic cryolite spray, as the re-
sultant mixture is not sufficiently adhesive. Daxads must be included,
even in Straw Oil sprays, with synthetic cryolite, as previous tests
have shown that their exclusion resulted in a mixture which settled
badly in the spray tank.
Spray No. 1 was the most adhesive formulation tested. Although
this spray is comparatively expensive, it may be applied much less
frequently in areas having excessive rainfall, where it would remain
effective for long periods when spray equipment could not be operated
in the field. Aluminum sulfate and water glass cannot be omitted from
this formulation, as they form an electrolyte which prevents inversion
of the spray mixture. This electrolyte may be omitted when unconditioned
natural cryolite is used or when Straw Oil-340 is used instead of fish
In 1942 a special study was made to determine the relationship be-
tween cryolite residues on foliage and adult beetle mortalities in
potted-plant cage tests. The mortalities were determined by the Division
of Cereal and Forage Insect Investigations and the chemical analyses by
the Division of Domestic Plant Quarantines. Since cotton leaves were
used for those studies and gallberry foliage in the tests previously
reported, an attempt was made to interpolate the mortality-residue
ratios obtained in the 1942 tests with the residues from the various
concentrated sprays on gallberry foliage. Cotton, peanut, and gallberry
leaves were photographed and the leaf images cut out and weighed, to
Tfte .- of various cryolite concentrated-spray
for o' 'fort, Miss., August-September 1945.
No. 0 -:c.n Cost Loss from Cryolite
S (QuaI.t Pr 50 initial remaining 2/
gal. of spray) 'deposit/ rg_
1 Aluminum sulfate 4 lb. $12.26 38 118
Water glass 12 lb.
Natural cryolite 1/ 100 lb.
2 Igepal 1 pt. 10.85 54 55
Natural cryolite 1/ 100 lb.
Straw 01-340 2 gal.
Kerosene _/ up to 1 pt.
3 Daxad 11 4 oz. 12.14 60 45
Daxad 14 28 oz.
Synthetic cryolite 100 lb.
Fish oil 2 gal.
4 Aluminum sulfate 4 lb. 11.17 72 35
Water glass 12 lb.
Igepal 1 pt.
Natural cryolite / 100 lb.
Straw Oil-530 2 gal.
5 Daxad 11 4 oz. 11.05 75 50
Daxad 14 28 oz.
Synthetic cryolite 100 Ib.
Straw Oil-5340 2 gal.
6 Aluminum sulfate 4 Ib. 10.90 80 P5
Water glass 12 lb.
Igepal 1 pt.
Natural cryolite / 100 Ib.
7 Igepal 1 pt. 10.58 83 26
Natural cryolite / 100 lb.
Kerosene 4/ up tol pt.......
i_ Average of 8 collections.
2/Per 12 grams (dry weight) of gallberry foliage. Average of 9
/ All natural cryolite contained 0.25 percent of conditioner added
by the manufacturer.
h/ Before final addition of water to reduce foaming.
obtain the comparative dry weight-leaf surface ratios in the three
plants. When cryolite residues on gallberry foliage after 4.27 inches
of rainfall are considered, only the first three formulations of the
1945 tests as listed in table 2 should give the highest mortality re-
ported in the 1942 tests, viz., 92.8 percent with natural cryolite.
Field tests were conducted at Florala, Ala., in which adult-beetle
mortalities were used as the criterion of effectiveness of the different
spray formulations. The sprays were applied to vegetation in idle and
cultivated fields at the rate of 2 pounds of cryolite per gallon of
spray with the concentrated-spray machine delivering at the rate of 6j
gallons per acre. The natural oryolite-Igepal-Straw Oil formulation
(No. 2) was compared with the synthetic cryolite-Daxads sprays (Nos. 3
and 5). Also included in these tests was a spray formulation containing
natural oryolite with aluminum sulfate and water glass. This was an
opportunity to study the effect of aluminum sulfate on cryolite sprays.
It was believed that the inclusion of aluminum sulfate might break down
the cryolite and render it ineffectual as an insecticide. The results
of these tests are shown in table 3-
Table 3.--Mortality of white-fringed beetles after spraying with various
oryolite concentrated-spray formulations and after dusting with
natural and synthetic cryolite. Florala, Ala., 1945.
Formulation 3rd day 7th day 14th day '
F orao (rein 1.5 in.) (rain 3.6 in.) (rain 5.1 in.): A"veg
Percent Percent Percent Percent
2 84 76 50 70
3 83 73 42 66
4 85 71 26 61
5 69 40 22 44
Nature 1, with
conditioner 49 46 2R 40
Synthetic 49 44 39
These mortality tests further substantiated the results obtained with
chemical analyses, viz., that the natural cryolite-Straw Oil (No. 2)
formulation was just as good as, or better than, the synthetic cryolite
spray with fish oil (No. 3). Moreover, as previously determined by chemi-
cal analyses, the synthetic oryolite-Daxads spray with Straw Oil (No. 5)
was inferior to that with fish oil (No. 4). The aluminum sulfate and
water glass showed no detrimental effect on the toxicity of the cryolite
6 *:. 2). i mortalities with conditioned
+ ..I : o --'t "..idll .h same as thoe with synthetic
cryolite ..: --, "e'-. **--. between these t-,o .,-aterials were
amifes"--th oe" ." th .- fo.lata,,, tested, The aiparent deoreas-
1.r**. il.. -. r due to the counting of beetl-s emerging
e eore :4. 7 '*'.re te --cie, and to removal of dead beetles by ants.
...o <" 0 .',:. .. fl ]_- ,--_Dir :ag "rr 194 a control .eason cryolite conoen-
tr.J.t,-1? -':E. .- E-.-aJ.i EIlftj, lime f(or water glas), and Straw
Oil-34D were .m. --.,. extensively i. all white-fr.nged beetle control
areas. Thes .*w -- ... -v ,ry were mnde oi-ly with conditioned natural
ot-.tlit as tes .. demonstrated their ineffi.cy with synthetic
oryolit.. The thetio aerial was used as a dust, and in sprays with
fish oil as -i'.-. -.esi' "here the offensive odor was not a factor.
Both spr "p> _v. d to !.,,- equally satisfactory agaL"Lu adult white-
friE~e-i mO-1aJ','ze6 . 41e end of the season the aluminum sulfate-
water gs b.t.on As slated from the conditioned natural oryo-
Iite-.Igepal'2 .--.t A T, f oulat '.Dr, and in actual control operations this
new upray appeared -.> maintain better cryolite deposits than the syn-
thetic .' ..le D :t _,, oil spray. No foliage injury from Straw
Oil-3L,? ? s r:p,.-i_,., ali-.1-rLh 5,0
du;-.,.- b c_-ro season and some of the heavy dosages were applied to
extreinly co cctr-ted spray-conditioned natural cryolite 250
pounds, Igepal ;- pints, S-ra.w Oil-340 6 gallons, ,?r.d water to make 50
gallons -was apt.liea by airplane in regular control operations during
1946. This spray, whichdi contained 5 pounds of insecticide per gallon of
total liquid, was applied at the rate of 2.8 gallons (l pounds of cryo-
lite) per acre with complete satisfaction. There was no agitator in
the .pray tank of the airplane, but none of the pipe lines were clogged
during opo rations. This spray was so well suspended that no residue
was left in the tank after the lines had been completely emptied. An
experimental batch of this highly concentrated spray was left undisturbed
in the spray tank for mouths, but it was easily resuspended after that
period with a small amount of agitation.
Summary and Conclusions
Studies on a-D-iesive agents for dilute and concentrated cryolite
spray& were .ctI.-t'ed in 1944 and 1945 at Gulfport, Miss. Although the
primary purpose was to find substitutes for linseed oil, which was una-
vailable, and fish oil, which was scarce and expensive during the war
years, several formulations were developed which contained adhesive
agents as satisfactory as fish oil and were also less expensive and
odoriferous. The sprays were also more easily prepared. Aluminum
sulfate and lime formed a satisfactory adhesive agent for natural or
synthetic dilute sprays and Straw Oil-340 in conditioned natural cryo-
lite concentrated sprays. A highly concentrated spray was developed
and used successfully in airplane equipment. The formula was conditioned
natural cryolite 250 pounds, Igepal 11 pints, Straw Oil-340 6 gallons,
and water to make 50 gallons.
It is evident from these tests that the turntable technique in ad-
hesive studies in the laboratory was not satisfactory, especially when
concentrated sprays were used. Artificial weathering, such as indoor
drying for several hours, the use of an electric fan to simulate wind
conditions, controlled rainfall from special machines, or any combination
of these methods, could not be used in lieu of natural weathering for
determining the comparative efficacy of different spray formulations.
Moreover, artificial surfaces, as glass or wax-coated glass, were found
to be less satisfactory than natural leaf surfaces for studying the ad-
hesive qualities of different cryolite spray formulations.
0 METAL PAN
"^ l -', *:' ...... - 2 METAL
* ^ ^ e:1=^ | \ o-- o 0-"%eve .
-ANGLE T ---- PAN BOTTOM
/ IONS-- PLASTER
S --CAPILLARY GLASS TUBE
IN" -CAPILLARY~' ~ RSRCE
---- A f ~ DISCHARGE RESTRICTED
vIcs A 0 AA TUBE To DROP WATER
6 IwX3" WOOD
Sus ended METAL
ISp d / --- BAFFLE
above Plants PLATE
.. .. FLASK
'---- TIM CAN
.- R1--WOOD BASE
SfS------- WIRE NAIL
.-- DEVICE FOR
>:..:.. -::: R EVO LVI a
EACH R.E 1OLUITION
OF TURN TABLE
/ ---"HOW. CLOTH
RAIN / WOOD BRACE
6'fo 20' METAL APRON
.-from C, / / .
plant- WOOD BLOCK
Figure l.-Turntable apparatus for testing adhesiveness of cryolite sprays.
UNIVERSITY OF FLORIDA
3 1262 09239 1894
"** ('W -^I" ~ iy
~*% ~ -
Figure 2.-Dilute-spray machine
applying 150 to 200 gallons of cryolite spray
Figure 3.-Concentrated-spray machine applying 6 to 6| gallons of cryolite spray