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Патент USA US2503744

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April 11, 1950
. Filed Aug.
12, 1947
FIG. 2
Patented Apr. 11, 1950
John W. Kenney, Jr., Long Beach, and Pascal M.
Rapier, Redondo Beach, Calif., asslgnors to
Great Lakes Carbon Corporation, a. corporation
of Delaware
Application August 12, 1947, Serial No. 768,166
12 Claims. (01. 252—89)
This invention relates to the dry cleaning of
fabrics and speci?cally to means by which the
solvents used by dry cleaners may be rendered
electrically conductive and maintained in that
A purpose of the invention is to provide a
?lter-aid through the use of which a used sol
vent may be clari?ed for reuse and simultane
ously rendered electrically conductive.
oleate, together with a free fatty acid, usually
olelc acld-—i. e., a superfatted soap. This method
may be made effective for reducing the resis
tivity of the solvent to the level at which re
deposition (commonly referred to as “linting")
is prevented, and the added soap, under suit
able conditions, functions also as an important
aid to cleansing.
The use of alkali metal soaps as cleansing aids
A purpose of the invention is to provide meth 10 is Well established, but when an attempt is made
to render the solvent su?iciently conductive in
ods and agents through the use of which in the
manner, serious di?iculties are encountered.
clari?cation of solvents the redeposition of soil I
First, the quantity of soap required to produce
and lint on the cleaned fabrics may be wholly
conductivity is very large, and as the added soap
is removed when the used solvent is recondi
In the use of gasoline as a cleaners’ solvent,
tioned by ?ltering, this unduly large quantity
once common practice, a serious riskof ?re or
must be added each time the solvent is ?ltered.
explosion resulted from the accumulation of
This is an item of expense which is very nearly
static charges on agitation of the solvent with
the fabrics being cleaned, and many attempts
Again, the alkali metal soaps are insoluble in
were made to ground oil’ and dissipate these
the commercial solvents other than in the pres
charges. With the increasing use of Stoddard
ence of enough free oleic acid to form a ternary
solvent and some of the chlorides of carbon to - system, and this system is unstable in the pres
replace gasoline, this risk has substantially dis
ence of material quantities of water, an emul
appeared, Stoddard solvent having a ?ash test
sion being formed and the conductivity disap
of 100° Fahr. or above while‘carbon tetrachloride
pearing. Thus great care is required in the ad
and perchlorethylene are nonin?amma'ble.
dition of the water which is necessary‘to ren
The static ‘charges which formerly engendered
risk of explosion are also effective in causing dep
osition of soil and lint on the fabrics being
cleaned, redeposition of suspensoids occurring as
der the soap effective as an aid to cleansing.
And ?nally, in order to avoid the very undesir
able'presence of soap and free fatty acid in the
?nished work, it is necessary to omit these ad
ditives during the break and rinse stages, thus
leaving the solvent highly resistive in the par
the charge increases during the ‘period of the
run. The redeposition of soil solids is detri
mental to the appearance of white and light col
ticular periods during which- conductivity is most
ored fabrics while the accumulation of. lint on 35 essential to the prevention of linting.
dark colored woolens, velvets and the like is still
We have discovered that such of the oleates
more detrimental to the quality of the ?nished
of the heavy metals as are oil-soluble, when add
ed to the solvent in minute quantity and under
The mere grounding of the cleaning vessel
suitable conditions, are capable of rendering the
does not suffice to prevent the accumulation of 40 solvent conductive to such degree that linting
is wholly prevented. We have also discovered
static because of the high dielectric strength of
that the quantity of heavy metal oleate required
the various solvents, and many attempts have
for this purpose is so small that it may be pres
been made to render either the fabrics them
ent in the solvent during the last stages of the
selves or the solvent batch electrically conductive.
Thus, it is somewhat common practice to hu 45 wash, thus affording protection against linting
throughout the operation. We have also dis
midify the fabrics prior to their immersion in
covered, and this is most surprising, that these
the cleaning bath, thus causing them to dis
heavy metal soaps, unlike the superfatted al
charge their static on touching the wall of a
kali metal soaps, are not removed from the sol
grounded cleaning vessel. This method is mod
erately effective but has the obvious disadvan 50 vent by the work nor by ?ltration with diato
maceous earth ?lter aids, and that the conduc
tages that humidi?cation is a tedious operation
tivity imparted by them persists through repeat
and one which, if carried too far, may result
ed uses and ?ltrations.
in damage to the fabrics.
So far as we have been able to determine, all
The step most commonly taken is to add to
the bath an alkali metal soap, usually sodium 55 of the‘ heavy metals which form oil-soluble ole
ates are functional for this purpose to some
of alkali metal soaps which, if used, should be
degree, though their relative effectiveness and
utility vary over a wide range. For practical
purposes the choice of a metal to form the ole
ate lies ‘between six of the group II metals (mag
nesium, calcium, zinc, strontium, cadmium and
barium), three of the group VIII metals (iron,
added in such quantity only as is required to ob
tain the maximum cleansing effect.
In the form of the invention in which the
heavy metal oleate is produced in situ it is neces—
sary to have present in the solvent a quantity of
an alkali metal oleate sufficient to produce the
nickel and cobalt), and copper. The utilities of
desired quantity of heavy metal oleate by double
certain of these metals are limited to special
decomposition, together with a sul?cient quantity
cases: of zinc, barium and copper by the tox 10 of water to produce ionization. The alkali metal
icity of the oleate, and of iron, nickeLcobalt
soap merely provides a source of fatty acid radi
and copper by the relatively dark colors of the
cals for reaction with the heavy metal salt and
oleates. A trace of a toxicpleate in rugs, woolen , the quantity requisite for this purpose is ex
drapes and the like might:well be'advantageous‘; tremely small, a mere fraction of the quantity
as moth protection, while a dark color'would be
ordinarily added to the solvent as a cleansing
harmless in the cleansing of dark or black fab
aid. The presence of a quantity of alkali metal
rics. The quantity of the oleate retained by the
soap greater than that required for the reaction
work after centrifuging would be almost disap
with the heavy metal salt does not interfere,
pearingly small, considering the extremely ‘low ’
nor does it affect conductivity in either direction.
concentration of the oleate in the rinse solvent. 20 In practice, the soap added will usually be super
On the score of low cost combined with high ef
fatted, but the free oleic acid of such a soap is
fectiveness our preference is for the oleates of
not appreciably reactive with the heavy metal
magnesium, strontium, barium and calcium.
salt, and free oleic acid may not be substituted
The stearates of these metals have not been
for alkali metal soap other than in instances
found useful for this purpose and, so far as we 25 in which a hydroxide of an alkaline-earth metal
are at present aware, only the oleates are func
is substituted for the heavy metal salt.
tional to a useful degree.
Any water-soluble salt of one of the metals
The invention may take two forms, in one of
above named may be used in admixture with the
which the oleate as such is added to the solvent
diatomactous earth ?lter aid, though the nitrates
while in the other it is formed in the batch by 30 and chromates, while fully functional, might be
the reaction of a salt of the heavy metal with
undesirable because of the possible detrimental
an alkili metal soap previously addedto or present
effect of traces of the corresponding alkali metal
in the solvent. In either case the agent is in
salts which might remain in the ?nished work.
troduced into the solvent in intermixture with
By preference, we use the chlorides and such of
a diatomaceous earth ?lter aid, this step being 35 the sulfates and hydroxides of the named metals
essential to practical operativeness for reasons
as are su?iciently water-soluble for reaction.
which will appear hereinafter.
These substances are referred to collectively
In the ?rst form of the invention, the pre
herein as water-soluble inorganic compounds of
ferred oleate is dispersed throughout the ?lter
the metals named.
aid powder in a ?nely comminuted condition, in
The quantity of the salt added to the ?lter
small proportions of the general order of 0.5%
aid is not critical but will ordinarily be of the
to 1.0% by weight, these ?gures being suggestive
order of 0.1% to 1.5% by weight, varying some
only and not critical. As these oleates are found
what with the combining weight of the metal.
in commerce they are in the form of waxy or
The salt or hydroxide, as the case may be, is
rubbery grains or masses, very slowly soluble in
reduced to a. ?nely powdered condition and inti
the solvent and extremely difficult to reduce to 45 mately blended with the powdered ?lter aid. The
powdered form. We have therefore devised a
blend is applied to the solvent in either manner
method, later described, by which these soaps
above described, i. e., by addition to the batch
may be formed by direct reaction between oleic
of solvent or by formation of a ?lter precoat
acid and the oxide or hydroxide of the metal, in
through which the solvent is passed. The re
the absence of water, the resulting product being 50 action between heavy metal salt and alkali metal
friable and readily reduced to ?nely powdered
soap goes to completion with some rapidity and
form by grinding.
as fast as the heavy metal soap is formed the
The ?lter aid containing the heavy- metal
solvent ‘becomes ' conductive.
oleate may be added to the batch of solvent at 55
The ?gures in Table 1 below illustrate the
the beginning of the run, or it may be formed
effectiveness of several of these salts in reduc
into a precoat on a ?lter leaf and the solvent
ing the resistivity of a solvent containing a super
circulated through it. In either case‘ the oleate,
fatted alkali metal soap and in maintaining the
being in a ?ne state of subdivision and intimately
reduced resistivity through a step of ?ltration to
dispersed throughout the earth, passes rapidly 60 brightness with an inert ?lter aid.
into solution and the solvent is rendered con
In these experiments one batch of 1000 ml. of
ductive immediately. The quantity of the oleate
fresh solvent having a resistivity of 10,000 meg
required to maintain conductivity is of thegen
ohms was treated with 1.3 grams of a commercial
eral order of 0.005% by weight in the case of
dry cleaners’ soap, then agitated for 20 minutes
magnesium ‘oleate or slightly more in the use of 65 with 10 grams of diatomaceous earth ?lter aid
and ?nally ?ltered to brightness through paper.
the other oleates.
The solvent so treated does not lose its con
Ten additional batches were treated each with a
ductivity by repeated ?ltrations through diato
mixture of 1.3 grams soap and 2.6 grams water,
maceous earth ?lter aids, through conductivity
agitated for 20 minutes with 10 grams of the same
will diminish as the concentration decreases with 70 ?lter aid with which in nine cases 0.0004 gram
the addition of make-up untreated solvent and
molecule of the various salts named in the table
may be reduced or destroyed by the use of highly
had been blended, and ?nally ?ltered to bright
adsorbent “sweetening” powders, a subjectwhich
ness. The resistivity in megohms instrument
will be considered separately. The treated sol
reading was determined on each batch, both be
vent is not affected by the presenceor absence
fore and after ?ltration.
‘ The other alternative is to add to the adsorptive
?lter aid or sweetener a small quantity of one of
the heavy metal soaps and also a somewhat in
Resistivity in Megohms
Before Fil- After Fil
1, 500
10, 000
Soap only ____________ ._
Soap and water ______ _-
Soap + water + MgOl
Soap + Water + MgSO4-7H2O ____ __
5, 000
10, 000
290 10
Soap + Water + MgSOi, Anhydrous.
Soap + Water + OdCl, ____________ __
Soap + Water + Each“
Soap + water + SrCln _ .
Soap + water + OaCh".
Soap + Water + ZnSO4 ___________ __
Soap + water + A12 (SO4)3 ________ ..
1, 200
creased quantity of a heavy metal salt, using this
agent on a solvent containing enough alkali metal
oleate to produce double decomposition. As
the purifying treatment to a batch of‘ solvent
not carrying any fabrics to be cleansed.
shown in Table 2 below, the effect of the double
addition'of soap and salt is to provide an imme
diate supply of the heavy metal soap for the
initial production of conductivity and a supply
of soap more slowly produced by reaction to re
place that withdrawn by adsorption.
The results of these additions to the sweetening
agent in preventing undue rise in resistivity dur
ing the period of a normal dry cleaning run are
In Fig. 1 of the attached drawings, in which
shown in Table 2 below. In these experiments a
these results are shown graphically, the point at
used solvent, having an initial resistivity of about
the upper left corner of the chart is the original
resistivity of the solvent; the low point is the 20 10,000 megohms and a resistivity in the condition
taken of about 1,200 megohms (due to the pres
resistivity to which it is brought by the added
ence of superfatted soap) was intimately blended
agents without ?ltration, and the right hand
with 1.3 gram soap and 2.6 gram water per 1000
point is the resistivity after ?ltration, the upward
millilitres. Successive batches of this low resis
slope of the line indicating the stability of the
imparted conductivity to ?ltration.
25 tivity solvent were then strongly agitated for
twenty-?ve minutes with one of the sweeteners
A resistivity not exceeding 1750 megohms (as
measured on the instrument used) if constantly
described in the second column of the table,
parallel batches being treated with the sweeten
maintained, is su?icient to avoid linting and soil
ing powder per se and with the same sweetener
redeposition. Soap alone (test 1) in the quan
with the addition of 1% crystalline magesium
tity used, did not meet the test after ?ltration;
sulfate and %% magnesium oleate, these quan
soap and water (test 2) in proportions commonly
tities being weight percents of the total sweet
used in cleaning room practice did not meet the
ener and the sweetener added being in each case
test. The added salts, with the exception of
1% of the weight of the solvent. At the end of
aluminum sulfate, brought the resistivity to a
considerably lower ?gure and held it at a lower 35 each treatment, and without ?ltration, the instru
ment resisivity of the solvent was again deter
level through the step of ?ltration, affording pro
tection against the advent of water in such quan
tity as would destroy the conductivity produced
by the superfatted soap and also affording room
Resistivity After
for further reduction of even thevery minute 40
quantities of agents used.
Composition of Sweetener
All of the resistivities mentioned herein are ob
served ?gures with the instrument and cell used
Additives Additives
and may be converted into speci?c resistivity in
megohms per centimetre cube by dividing the ob 45 1 Filter Aida-Synthetic Adsorbent___.
10, 000
served ?gure by 0.00702.
As above stated, permanent conductivity is at‘
tamed only when the ?lter aid used is inert, i. e.,
substantially nonadsorptive. When ?lter aids
having decolorizing properties are used, the heavy 50
metal oleate may be selectively adsorbed and thus
removed from the solvent, the desired conduc
tivity being reduced or lost.
It is possible, however, by either of two modi
Filter Aid+Synthetic Adsorbent+
7,v 500
l, 300
Commercial Sweetener A
2, 000
Carbon _________________________ _ _
Synthetic Adsorbent A. _
10, 000
l, 700
Synthetic Adsorbent B ______ ._a___.
1, 900
Filter Aid-i-Acid Treated Clay+
Filter Aid-i-Raw Adsorbent Clay-1»
Carbon _________________________ __
Carbon _________________________ ._
‘ 8
Commercial Sweetener B_ _
5, 000
l, 050
4, 500
l, 100
7, 600
Filter Aid-i-Activated Clay _______ __
5, 000
1, 400
?cations of the above procedure, to maintain such 55 The comparisons are shown more eifectively in
Fig. 2 than by the ?gures in the table. It will
degree of conductivity as to avoid linting and at
be noted that in all cases the treatment with the
the same time to maintain the purity of the sol
unmodi?ed sweetener brought the solvent to a
vent by the use of adsorptive sweetening powders.
resistivity far above that which is consistent
One alternative is to alternate the treatment
by which conductivity is produced with a purify 60 with freedom from linting. On the other hand,
the sweeteners modi?ed by the addition‘ of the
ing treatment with a sweetener, which may re
salt and of a minute quantity of the oleate car-_
duce or even destroy the conductivity and require
ried the solvent above the safe level in only two
that it be reestablished. In this procedure the
of the tests (3 and 5) while in four of the tests
solvent is maintained in a conductive‘ condition
in either manner above described until such time 65 the resistivity was increased to only a minor de
gree (l, 2, 4 and 8) and in three it is reduced by
as it becomes overloaded with coloring matter
the treatment with the sweetener (6, 7 and 9).
or other adsorbable impurity. The impure sol
Purifying treatments of this nature may be in
vent is then given a purifying treatment with an
terspersed between runs in which an inert ?lter
adsorbent powder, after which it is brought back
to the desired conductivity (if then too low) by 70 aid is used without interrupting the work of the
cleaning plant.
the addition of a ?lter aid carrying a heavy metal
Table 3 below illustrates the bene?cial e?ect
soap or by the addition of a ?lter aid carrying a
of the addition of a heavy metal salt to cleaning
heavy metal salt to a solvent containing an alkali
batches in which an alkali metal soap was used
metal soap. The same apparatus may be used
for both treatments but it is desirable to apply 75 as a cleasingsaid. These ?gures are the results
of ‘plant scale runs in each of which the quan
tity of ?lter aid added to the batch was 2 pounds.
serving the consistency of the cold mix it was
heated for from 1 to 2.5 hours at 110° 0., until
In runs Nos. 1 to 6 inclusive the ?lter aid was
the ?lter aid was straight diatomaceous earth,
reaction appeared to be complete. The con
sistency of the heated batch was observed after
cooling, and the products were then milled to a
?ne powder under identical conditions. Finally,
and in runs 11 to 15 the ?lter aid was the di
0.05 gram of each product was dissolved in 110
diatomaceous earth containing 0.5% by weight of
magnesium sulfate, crystalline. In runs 7 to 10
atomaceous earth used for making the agent
ml. of fresh Stoddard solvent and the observed
used in runs 1 to 6 but without the addition of
resistivity of the solvent determined in megohms.
the salt. The observations of dusting and linting 10 The results of these experiments are set forth in
were made by trained observers.
Table 4 following:
Oleic Acid
Millability Megohms
,1I:§a%Zr{%§(1%/i¥§9::""m-""mm-‘wit: }Fairly Hard." Fairly Hard.-. Fair ....... ._
2 parts
_ _ _ _ _
_ }Hard ________ __ Very Hard... Very Good..
2 parts OP Mg0___
4 parts
2 par 5
_____do _______ __
giggug _
2 parts Mgooamu
4 parts Cale MgO _ _
. . _ _ __
1 part Stearic Adm
Hard ________ __
Good ______ _.
Hard.___ Very Hard_-__ Very Good__
Thick Pastem ...._do ____________ ..... ._
_ _ _ _ _ __
Fluid _______ >_
Hard ________ __
Good ______ __
8 parts Cale MgO _ _ _ _ _ _ . _ _ _ _
_ _ . _______ ..
Very Hard__._
Very Good“
4 parts Activated Brucite.-.
_____do _______ ._
Fairly Hard.-.
Fair _______ -_
2, 000
8 parts Activated Brucite.
._-__do _______ __
Hard ________ __
Good ______ ._
4 parts Cale MgO
4 pargsclgllslmge.
"""" '“
}Fmr1y Hard"-
._._ _..._d0 ....... _.
2 parts Mg (0H): _____________________________________ ._d0 _______ ._
3 parts Cale MgO _________ __
4 parts Heavy MgO ________ __
Plant test data
Properties of Oxides
Type Garments
Weight Quarts
Qbserved ,Du?t‘
3 N55“:4
5__ __
Particle Size microns _____________ _.
mg and Lmtmg '
Surface Area’, sq. meters/gram .... __
12. 2
Per cent through 325 mesh ________ __
99. 3
0. 54
l. 8
53. 7
________ __
The consistency of the cold mix is determined
by the rapidity of the reaction, which in turn ap
Velvet Drapes._--_
2 L_Do_.
Men’s Overcoats
4 HDo. L_ _
‘g’ L§‘t‘i7§g_ mung‘
the labor required for mixing. With the excep
12____ Men:sSuits_____
tion of the single test using four equivalents of
activated brucite, in which reaction obviously was
not complete, all of the products proved fully
12:: ?i?essflgglrllsieléaéigi:
15____ Men's Overcoats ______ __
pears to be a factor, of the particle size of the
oxide. So long as the ?nal ‘product is hard and
readily millable it is desirable to select reagents
45 which give a soft or ?uid cold mix, thus reducing
The quantity of soap used in each of these runs 50 functional for the purpose of avoiding linting
when mixed with ?lter aid in the manner above
was that customarily used for its effect in cleans
ing the fabrics and only a most minute part of
We claim as our invention:
it was consumed by combination with the mag
nesium salt.
‘1. The method of conditioning a dry cleaning
The production of mixtures of ?lter aid with
solvent to avoid linting and dusting in the dry
the heavy metal soaps of oleic acid is rendered
very di?icult by the unfortunate physical proper
cleaning‘ of fabrics which consists in contacting
ties of these bodies. As found in commerce these
?lter aid containing from 0.25% to 50% by
said solvent with a powdered diatomaceous earth
substances are tough and gummy solids or'very
weight of an oleic acid soap of a metal selected
viscous semisolids, impossible to reduce to pow 60 from the group consisting of magnesium, cal
dered form and therefore extremely di?icult to
cium, zinc, strontium, cadmium and barium, and
disperse in small proportion through a mass of
thereby causing said solvent to dissolve su?icient
?lter aid.
of said soap to reduce the resistivity of said sol
‘ We have discovered that the heavy metal oleates
vent per centimetre cube to not over 250,000
may be produced by direct reaction between oleic 65 megohms.
acid and an oxide, hydroxide or, in some cases,
a carbonate of the metal, and that the product
of such reaction may be pulverized readily when
solvent to avoid linting and dusting in the dry
cleaning of fabrics which comprises: dispersing
an excess of the metallic compound is used and
an alkali-metal oleic acid soap in said solvent,
' 2. The method of conditioning a dry cleaning
the reaction is completed by heating.
70 and contacting the solvent containing said soap
For example, in the following experiments,
with a powdered diatomaceous earth ?lter aid
oleic acid was mixed at 25° C. for about 5 min
containing from 0.1% to 1.5% by weight of a
utes with from 1.5 to 8 combining weights (re
water-soluble inorganic compound of a metal
ferred to in the following table as “parts”) of
selected from the group consisting of magnesium,
various basic magnesium compounds. After ob 75 calcium, zinc, strontium, cadmium and barium,
and thereby producing and dissolving in said
solvent a su??cient quantity of the oleate of said
metal to reduce the resistivity of said solvent
per centimetre cube to not over 250,000 megohms.
3. The method of conditioning a dry cleaning
solvent to avoid linting and dusting in the dry
cleaning of fabrics which comprises: dispersing
the point at which linting and. dusting are
avoided in the use thereof, consisting substan
tially of ?nely comminuted diatomaceous earth
and a minor proportion, not substantially less
than 0.25% nor more than 5.0% by weight, of
an oleic acid soap of a heavy metal intimately
dispersed therethrough, the metal of said soap
being selected from the group consisting of mag
an alkali-metal soap of oleic acid in said solvent,
nesium, calcium, zinc, strontium, barium and
and contacting the solvent containing said soap
with an adsorptive ?lter aid consisting substan 10 cadmium.
9. A composition substantially as recited in
tially of diatomaceous earth admixed with an
claim 8, in which the metal of said soap is
adsorbent solid selected from the group consist
ing of the natural, acid treated and activated
10. A composition for clarifying by ?ltration
clays and the adsorbent carbons, said mixture
a dry cleaners’ solvent containing an alkali metal
further containing from 0.1% to 1.5% by weight
ol-eate in dispersion and for simultaneously re
of a water-soluble salt and from 0.25% to 5.0%
ducing the electrical resistivity of said solvent to
by weight of an oleic acid soap, each of a metal
point at which linting and dusting are
selected from the group consisting of magnesium,
avoided in the use thereof, consisting substan
calcium, zinc, strontium, cadmium and barium,
of ?nely comminuted diatomaceous earth
thereby causing the solvent to dissolve sufficient 20 tially
and a minor proportion, not substantially less
of last said soap to reduce the resistivity of said
than 0.1% nor more than 1.5% by weight, of a
solvent per centimetre cube to not over 250,000
water-soluble, inorganic compound of a metal
meghoms and also providing a continuing sup
selected from the group consisting of magne
ply of last said soap, by reaction between said
sium, calcium, zinc, strontium, barium and cad
salt and said alkali-metal soap, to replace the 25 mium,
said compound being intimately dispersed
soap withdrawn from said solvent by said ad
throughout said diatomaceous earth.
sorptive ?lter aid.
11. A composition substantially as recited in
4. A composition for clarifying by ?ltration a
10, in which said metal is magnesium.
dry cleaners’ solvent containing an alkali-metal
12. A composition substantially as recited in
soap in dispersion and for simultaneously reduc 30
claim 4, in which said metal is magnesium.
ing the electrical resistivity of said solvent to
the point at which lint and dusting are avoided
in the use thereof, consisting substantially of
?nely comminuted diatomaceous earth inter
mixed with at least one solid adsorbent selected 35
references are of record in the
from the group consisting of the natural, acid
?le of this patent:
treated and activated clays and the adsorbent
carbons, said mixture further containing from
025% to 5.0% by weight of an oleic acid soap
of a metal and from 0.1% to 1.5% by weight of 40
a water-soluble inorganic compound of a metal
intimately dispersed therethrough, said metals
being selected from the group consisting of mag
nesium, calcium, zinc, strontium, cadmium and
5. A method substantially as recited in claim
1 in which said oleic acid soap is magnesium
Kritchevsky et a1. ___ June 16, 1931
Gebhart et a1 _____ __ Mar, 11, 1947
Great Britain ____________ __ 1893
Science for the Drycleaning
6. A method substantially as recited in claim
Association of Dyers and
2, in which said water-soluble compound is a
Cleaners of the U. S. and Canada) 1930, pp. 125,
compound of magnesium.
137, 138.
'7. A method substantially as recited in claim
Elliott: “The Alkaline Earth and Heavy Metal
3, in which said metal is magnesium.
Soaps,” Series No. 103, Reinhold Publishing Corp,
8. A composition for clarifying dry cleaners’
solvent by ?ltration and for simultaneously re 55 N. Y. C. (1946), pp. 84-90.
ducing the electrical resistivity of said solvent to
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