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‘2,405,276
atented Aug. 6, “E46
STATE 5
PATENT OFFICE
2,405,276
PROCESS FOR THE TREATMENT vOF WATER
BY SUPPRESSING THE IONS OF ALKALINE -
EARTH METALS
Ambrose George Taylor, Birmingham, England,
assignor to Calgon, Inc, Pittsburgh, Pa.
No Drawing. Application April 16, 1941, Serial
No. 388,818. In Great Britain May 6, 1940
26 Claims. (Cl. 210-723)
1
,
The invention relates primarily to the treat
ment of water intended to be used for domestic
purposes or in industrial processes or in steam
production, and in which the concentration of ,
calcium and/or magnesium ions is su?iciently
great to exercise an adverse e?ect'upon the use
of the water.
'
The object ‘of the invention is to improve the
condition of the water by reducing the concen
tration of free calcium and/or'magnesium ions.
A further object is to take into solution un
wanted deposits or scale consisting of calcium
and/or magnesium compounds, using water with
2
hours at 355° C. When the monosodium ortho
phosphate is heated to above 500° C., the yield
of insoluble metaphosphate rapidly decreases to
nothing, the resulting product being sodium, tri
metaphosphate which is water soluble and is
characterized by its inability to form a precipi—'
tate with metallic salts.
It has been reported (vide Pascal, Bull. Soc.
Chim., 1924, 35, 1119) that‘the Kurrol salt of
sodium can be formed-by crystallisation from
molten sodium metaphosphate.
With regard to the Kurrol salt of potassium, it
is already known that potassium metaphosphate
is readily obtained in a range of closely similar
out addition of acids. The method by which the
water-insoluble forms by removal of the elements
invention achieves the ?rst mentioned object is
of water from monopotassium phosphate by the
by the addition to the water to be treated of
action of heat above'approximately 250° C., or by
alkali metal metaphosphate preparations derived‘
cooling molten potassium metaphosphate. All
from the water-insoluble varieties of alkali metal
these water-insoluble forms of potassium meta
metaphosphates, and the method by which the
phosphate are usually designated in the litera
20
invention achieves the further object is by treat
ture as potassium Kurrol salt (vide Pascal, Bull.
ment of -the deposits of calcium and/or mag
Soc. Chim., 1924, 35, 1119).
» ~
nesium compounds with water containing water
According to the aforesaid bulletin, Pascal re
insoluble alkali metal metaphosphates or prepa
ported that sodium Kurrol salt could be pre
rations derived therefrom. Typical of the water
pared by rapidly heating Maddrell salt to fusion
insoluble alkali metal metaphosphates in ques 25 from
which the hexametaphosphate is formed on
tion are Maddrell salt (of sodium) (vide Chemi
quick cooling. By slowly cooling from the fused -‘
cal Society Annual Reports, 1937, p. 116) and
state, a glassy or crystalline mass forms, which,
Kurrol salts (of sodium or of potassium) (ibid.
for the most part, is insoluble in water. When
p. 118).
crystallization does not occur, the presence of the
30
Maddrell salt is formed by the removal of the
insoluble salt is indicated by the ?neness oi the
elements of water from monosodium orthophos
cracks and the milky appearance of the glassy
phate by the action of heat below approximately
mass. It is this insoluble form of sodium meta~
500° C. It is generally accepted that this salt
,phosphate that is called sodium Kurrol salt by
is not a single form but rather a mixture of
Pascal. The sodium Kurrol salt may be pre
at least two closely similar water-insoluble forms 35 pared
also by gently heating small quantities
which have not as yet been clearly characterised.
of sodium monoethyl phosphate. This salt swells,
As shown by Paul Pascal, in his paper entitled
“Research
on
the
Metaphosphates”
(second
gives off combustible vapors and leaves a porous
material the fusion of which is avoided for fear
note), Bull. Soc. Chim. 1924i, 35, pages 1122 to
1124, the insoluble sodium metaphosphate or 40 of reversion toward the insoluble forms. This
porous material should be pulverized and washed
Maddrell salt may be prepared by heating mono
freely over a vacuum ?lter in order to carry
sodium orthophosphate _to temperatures in the
away the soluble metaphosphates which might
range from 250° C. to about 505° C. but not above.
dissolve the insoluble substance. After having
At the lower temperatures, the monosodium
orthophosphate must be heated for longer periods 45 been dried in a dry vacuum, the product is homo
geneous, it fuses at 809°-811° C., giving upon cool
of time than at the higher temperature in order
ing confused crystals which are sharply fusible
to obtain a sodium metaphosphate or Maddrell
at 811° C., or 170° 0. above the fusion temper
_ salt which is 100% insoluble or substantially so.
According to the data on page 1122 of the above
ature for hexametaphosphate. ‘
‘
‘
The viscosity of the solutions is not constant
mentioned Pascal paper, monosodium orthophos 50
on account of the existence of several varieties
phate must be heated for 300 hours‘at 252° C. in
of Kurrol salts, which are changed from one
order to obtain 100% insoluble sodium meta
'form into another by a variation in tempera
phosphate, and that the insoluble metaphosphate
ture. Because of the slowness of the phenome
may also be obtained by heating for 142 hours
at 281° C., for 7'7 hours at 320° C., and for 2 55 non, the pure varieties may be prepared by rapid
2,408,376
quenching after having been kept at a ?xed tem
perature. When the above described material,
after having been washed and dried, is heated
v 1924, as. 1119).
Solutions of high viscosity may
also be obtained by dissolving these Kurrol salts
in other aqueous solutions containing alkali metal
to, and held at, a temperature of from 500° C. to
550° C. for periods of time varying from 25 to 120
minutes, and is then quickly quenched from this
temperature, the insoluble Kurrol salt is obtained
and shows a relatively low viscosity in a solu
or ammonium ions irrespective of the nature oi’
the anion. As already stated, I have found that
sodium Kurrol salt gives a'viscous solution with
water alone. I have also found that all these vis
_ cous solutions undergo a slowv change on standing
tion of 2N/100 of insoluble material and N/10
and a very much more rapid change on heating,
which is characterized by a large reduction in the
in hexametaphosphate. This characteristic re
mains the same so long as the temperature from
which the material is quenched does not reach, or
attain, a value of from590°-600° C.
viscosity.
phate. I have now found that all water-insolu
viscous state.
I have found that the water-insoluble forms of
sodium and potassium metaphosphate when dis
It has long been known (vide Pascal, Bull. Soc.
solved as already described, have- the power of
Chim., 1924, 35, 1131) that sodium and potassium 15 combining
with calcium and magnesium ions to
Kurrol salts dissolve in aqueous solutions of tetra
form
complexes
of great stability. This property
sodium pyrophosphate, sodium hexametaphos- ,
is
characteristic
of solutions in a viscous state as
phate (Graham’s salt) and sodium trimetaphos
above described and also of solutions in a non
ble forms of sodium metaphosphate will dissolve 20
in aqueous solutions of potassium salts and in
aqueous solutions of ammonium salts, i. e. in
aqueous solutions containing potassium or am
monium cations irrespective of the nature of the
The metaphosphate materials with which the
invention is carried into e?ect include solid so
dium Kurrol salt or a solution thereof in water,
solid mixtures of water-insoluble sodium and/or
potassium metaphosphates with alkali metal or
ammonium salts, mixtures of water-insoluble so
I have found that there also exists a dissolving 25 dium
and potassium metaphosphates which will
anions.
'
in?uence of water-insoluble sodium metaphos
phate and water-insoluble potassium metaphos
dissolve jointly as already mentioned, solutions
derived from any of the foregoing mixtures of
phate upon one another in the presence of water
salts, and also solid preparations derived in an
as a result of which the two water-insoluble sub 30 obvious manner, for example, by evaporation to
stances become dissolved jointly. _Th1s phenom
dryness of these solutions. The water-insoluble
enon is shown by mixing any water-insoluble
metaphosphates may also be used singly and
sodium metaphosphate with any water-insoluble
without admixture with other salts if the water
potassium metaphosphate, and adding water; the
to be treated already contains suiilcient univalent
mixing may be effected by any ordinary mechan 35 cation
to bring them into solution.
.
ical method and I prefer this method.
Having regard to the foregoing, the present in
Sodium Kurrol salt, prepared by crystallisation
vention consists broadly in eliminating from
from a melt, is referred to in the literature as
water the undesirable properties associated with
“insoluble.” I have found, however, that al
though apparently insoluble as judged by appear 40 the presence oi.’ calcium and/or magnesium ions
by adding to the water any of the aforesaid mate
ance when stirred for a short time with water, it
rials.
In particular the precipitation of insolu
is in reality not insoluble. When crystals of so
ble
calcium
and magnesium salts, e. g. lime soaps
dium Kurrol salt are kept in contact with cold
or calcium and magnesium carbonates can be
water they slowly‘swell'and become gelatinous
prevented in this way. It is also possible to dis
and later give a viscous solution. However, so
solve and hold in solution by means of these prep
dium Kurrol salt is made to dissolve most con
arations calcium and magnesium salts having
veniently by warming it with an aqueous solution
even very low solubility products.
_,
containing potassium or ammonium cations ir- -
respective of the nature of the anions. It is to be
noted that Maddrell salt di?ers from sodium
Kurrol salt by not swelling in water alone and by
dissolving more slowly than the Kurrol salt in
the presence of potassium ions, the comparison
being made at the same temperature for both. I
use the term “water-insoluble alkali metal meta
phosphates” for convenience, in spite of the above
described behaviour of sodium Kurrol salt.
Potassium Kurrol salt, prepared by crystallisa
tion from a melt, does not show to a noticeable
I am aware that water-insoluble alkali metal
metaphosphates can be dissolved in dilute solu-_
tions of strong acids and that the acid solutions
obtained can be neutralised by addition of alkali
metal and that the alkali metaphosphate formed
can be held‘ in solution by suilicient dilution with
water. Moreover, it has been stated in United
States Patent 2,130,557 (Casimir J. Munter) that
if Maddrell salt or Kurrol salt is dissolved in
strong acid without heating, the effectiveness of
the solution obtained by subsequent neutralization
extent the swelling in water alone. All water-in
is from 25% to 50% as great for repressing the
or ammonium ions.
being on the basis of the metaphosphate required
concentration of calcium ions as the e?ectiveness
soluble forms of potassium.metaphosphate will, 60 of
a solution in which all' the metaphosphate is
however, dissolve in aqueous solutions containing
present
as hexametaphosphate, the comparison
other univalent cations, for instance sodium ions
While some of these solutions of water-insolu 65 to eliminate a given quantity of calcium ions.
In contrast with this, it is shown in examples
ble alkali metal metaphosphates are readily ob
hereinafter given, that the preparations I have
tained in the cold, others are more conveniently
described derived from water-insoluble sodium
prepared by warming the water-insoluble meta
and potassium metaphosphates are quite as eifec- .
phosphate or metaphosphates in the presence of
tive as sodium hexametaphosphate (Graham’s
the appropriate aqueous medium.
70 salt) in repressing calcium ions. In view of the
It is already known that the insoluble Kurrol
metaphosphates of sodium and potassium when
dissolved in aqueous solutions of pyrophosphates
or hexametaphosphates ‘give rise to solutions of
foregoing I speci?cally exclude from the scope of
the invention herein claimed solutions derived
from water-insoluble alkali metal metaphos
phates by dissolving in strong acids, with Or with
notable ‘viscosity (vide Pascal, Bull. Soc. Chim., 75 out subsequent neutralisation.
2,405,276
6
tassium nitrate, and tested‘ as described above.
It is well known that another variety of sodium
gave the following results:
metaphosphate, the glassy form commonly called
The volume required for 5 mgm. calcium ions=9.5 ml.
Graham's salt or sodium hexametaphosphate.
The volume required for 5 mgm. magnesium ions=9.5 ml.
dissolves freely in water to give solutions which
Example 3
have the power of reacting with free calcium
or magnesium ions to form soluble complexes,
A solution of Maddrell salt was prepared by
and extensive use is made of this property for
adding 8 gms. of the salt to 1 litre of a boiling
water treatment, but I have found that the prep
solution of potassium carbonate containing 14.0
arations derived from water-insoluble sodium
gms. of KzCOs. The Maddrell salt went com
10
and potassium metaphosphates which are the
pletely into solution in a'few minutes. The solu
basis of the invention differ in an important re
tion was cooled and tested as described above.
spect from Graham's salt. Whereas solutions of
The volume required for 5 mgm. calcium ions=9.0 ml.
The volume required for 5 mgm. magnesium ions=10.0 ml.
Graham's salt are rapidly hydrated at the boil
ing point to orthophosphate. the solutions con
Example 4
taining the preparations derived from water 15
A metaphosphate solution was prepared by dis
insoluble sodium and potassium metaphosphates,
solving 40 gms. sodium Kurrol salt and 4.62 gms.
potassium Kurrol salt in 1 litre of water. The
solution was made slightly alkaline and boiled
maintain their property of repressing calcium
and magnesium ions concentrations by stable 20 to render it'non-viscous. It was then tested as
‘which are the basis of the invention, are at ele
vated temperatures much more stable and
soluble complex formation for long periods at
the boiling point. This property of stability at
high temperatures renders these preparations
particularly suitable for addition to water being
described above.
'
The volume ‘required for 5 mgm. calcium ions=9.0 ml.
The volume required for 5 mgm. magnesium ions=l0.0 ml.
E .rample 5
supplied to steam boilers in order to prevent feed
line deposits or to dissolve existing‘deposits.
An additional advantage which solid prepara
The stability of slightly alkaline solutions of
potassium and sodium Kurrol saltsds shown by
tions derived from water-insoluble sodium and ,
the following experiment:
potassium metaphosphates have is that unlike
8 gms. or" sodium Kurrol salt were dissolved in
Graham’s salt they are non-hygroscopic and 30 1 litre of 0.65% potassium carbonate solution.
may be exposed to a damp atmosphere without
deterioration.
»
The following examples show the calcium ion
and magnesium ion repressing power of prepara
tions obtained as already described from water
insoluble alkali metaphosphates. In Examples 1,
9.2 gms. of potassium Kurrol salt were dissolved
in 1 litre of 0.5% sodium carbonate solution.
These solutions were boiled under reflux for 6
hours and at the end of this time the percentage
of metaphosphate which had not been changed to
' ortho- or pyrophosphate was determined.
In the ,
2, 3 and 4, the method of test was as follows:
case of the Kurrol ‘salt of potassium or of sodium.
The water-insoluble alkali metaphosphate
approximately 80% of the phosphate was still
preparation was-made up to contain 8 gms. per
present as metaphosphate, whereas under the
40
litre of NaPOa, or the equivalent weight 9.25
same conditions and in the same time Graham’s
gms. per litre of K903. The metaphosphate solu
silt was hydrated to the extent of approximately
tions were gradually added to 50 ml. of an aque
7 %.
ous solution containing 5 mgm. of calcium ions,
Example 6
or 5 mgm. of magnesium ions, at 18° C. The
A solution of Maddrell salt was prepared by
volume required to reduce the concentration of 45
dissolving 8 gms..of the salt in 1 litre of a boil
calcium or magnesium ions to such an extent that
ing solution of potassium chloride containing 14
a permanent lather (i. e. a lather persisting for
gms. of KCl. 200 ml. of a solution of calcium
at least ?ve minutes) can just be obtained with
chloride containing 0.1 gms. of calcium ion per
standard soap solution is an inverse'measure of
litre,'\were boiled, and 10 ml. of a solution of so
the calcium or magnesium ion repressing power
dium oxalate containing 6.7 gms. per litre were
of ‘the metaphosphate preparation. The pH’ 'of
added. Calcium oxalate was immediately pre
the solution just before the addition of the soap
cipitated. The suspension Was kept boiling and
solution was adjusted so that it was very faintly
pink to phenolphthalein. For comparison with
the solution of Maddrell salt run in from a
the volumes quoted below, the number of mi. of
an equivalent solution of sodium hexametaphos
phate (Graham’s salt)_ required is 9.0 ml. for 5
burette until the calcium oxalate had completely
dissolved. The volume of metaphosphate solu
tion required was not greater than 36 ml.
mgm. of calcium ions.
The following may be cited as illustrative ex
amples of the application of the invention:
Ewample 1
In the softening of water by the lime-soda
process as ordinarily carried out, the residual
A solution of water-insoluble potassium meta
hardness of the water is usually such that the
phosphate was prepared in 1% sodium nitrate
total hardness (calcium and magnesium) is
solution. The solution was boiled to<- render it
equivalent .to about two parts CaCO: per 100,000
non-viscous and tested as described above.v
65 of water. Water. of this hardness reacts with
The volume required for 5 mgm. calcium ions=9.0 ml.
soap and precipitates insoluble calcium and mag
The volume required for 5 mgm. magnesium ions=10.0 ml.
nesium'soaps.
Potassium‘ metaphosphates prepared by heat
ing monopotassium phosphate at different tem
be avoided by addition of Water-insoluble potas
sium metaphosphate to the stock soap solution
This disadvantageous result can
peratures to convert it to metaphosphate, or by 70 made up for use in washing machines. A soap
cooling molten potassium metaphosphate, gave
closely similar results.
Example 2
solution which contains 2 oz- of soap per gallon
of water of the above- mentioned hardness can
be used as the stock solution, subsequently to be
mixed with four times its own volume of water
A solution of sodium Kurrol salt in 1% pc 75 of the above mentioned hardness; the addition
2,4053%
'
7
of 0.08 oz. of potassium metaphosphate, which
dissolves readily in the soap solution on account
of the sodium cation therein, is sumcient to pre
vent the formation of insoluble calcium and mag
nesium soaps, at 80°-100° C. which is the tem
perature ordinarily employed for washing in a‘
washing machine.
A further illustration is the following:
.
8
tassium metaphosphate usually referred to as
potassium Kurrol salt in an aqueous solution
containing ammonium ions.
'
7. The process of softening water by adding-to
it a metaphosphate solution in su?lcient amount
to soften the water, said metaphosphate solution
being obtained by dissolving the form of po~
tassium metaphosphate usually referred to as
In laundry practice it is important to ensure
that deposition of calcium or magnesium soaps 10 potassium Kurrol salt in an aqueous solution
containing sodium and ammonium ions.
‘does not occur at the rinsing stage. The water
8. The process of softening water by adding
used in this operation may be softened by adding
to it potassium Kurrol salt in solid form, and in
thereto a solution obtained by dissolving 2%
addition a salt of sodium, said Kurrol salt be
lbs. sodium Kurrol salt and 5 lbs. potassium sul
phate in 10 gallons of water. If the water to 15 ing in amount su?icient to soften the water.
9. The process of softening water by adding
be softened contains 2 parts per 100,000 of cal
to it potassium Kurrol salt in solid form, and in
cium hardness (expressed as C8'CO3) the amount
addition a salt of ammonium, said Kurrol salt
of solution required to treat 1,000 gallons will be
being in amount sufficient to soften the water.
2.88 gallons.
.
10. The process of softening water by add
A further illustration is the following:
'20 ing to it an amount, sufncient to soften the wa
'As has already been stated above, the stability
at elevated temperatures against hydration to . ter. of a metaphosphate solution containing both
orthophosphate of solutions of water-insoluble
potassium Kurrol salt and Maddrell salt.
11. The process of softening ‘water in which
alkali metal metaphosphates is a valuable prop
erty when they are used in the conditioning of 25 potassium Kurrol salt is added to the water to
be treated together with sodium Kurrol salt, said
boiler feed water to keep the feed lines free from
Kurrol salts being added in amount su?icient .to
deposited calcium salts. Consider a boiler tak
soften the water.
ing 100,000 lbs. per hour of feed water which
12. The process of softening water in which
has been softened by a lime-soda process and
contains 1.1 parts per 100,000 of calcium hard 30 potassium Kurrol salt is added to the water to
be treated together with Maddrell salt, the Kur
ness and 0.4 part per 100,000 of magnesium
rol and Maddrell salts being added in amount
hardness; the blowdown is assumed to amount to
su?icient to soften the water.
10%; the requirement of metaphosphate is 1.27
13. A water softening composition comprising
lbs. of potassium metaphosphate or 1.1 lbs. so
dium metaphosphate per 100,000 lbs. of feed wa 35 a water-insoluble sodium metaphosphate in an
aqueous solution containing potassium ions.
ter. Su?icient of a stock solution of metaphos
14. A water softening composition comprising
phate to treat 400,000 lbs. of water is run into
a water-insoluble sodium metaphosphate in an
the boiler feed water every four hours, the addi
aqueous solution containing ammonium ions.
tion being completed in five minutes. The stock
15. A water softening composition comprising
solution may be made up by dissolving 10 lbs. 40
potassium metaphosphate and 10 lbs. sodium
sulphate in 50 gallons of water. Alternatively, a
solution prepared by heating 7 lbs. 5 ozs. potas~
a water-insoluble potassium metaphosphate in
an aqueous solution of sodium nitrate.
16. A mixture of effective amounts of, water
insoluble sodium and potassium'metaphospha‘tes
slum metaphosphate and 2 lbs. 11 ozs. Maddrell
salt with 50 gallons of water may also be used. 45 characterized by the fact that when such mixture
is added to water which is heated, a reaction
What I claim is:
takes place resulting in the dissolving of the
1. The process of softening water by adding
sodium and potassium metaphosphates, whereby
to it a metaphosphate solution in su?icient
the resulting aqueous solution exhibits the prop
amount to soften the water, said metaphosphate
solution being obtained by dissolving the form 50 erty of softening water by repression of the cal
cium and magnesium ions, and of dissolving cal
I of sodium met'aphosphate usually referred to as
cium and magnesium salts such as calcium and
Maddrell salt in an aqueous solution containing
magnesium soaps.
,
potassium ions.
2. The process as in claim 1, in which potas
sium ions are replaced, at least in part, by am
monium ions.
3. The process of softening water by adding
.I to it the form of sodium metaphosphate usually
referred to as Maddrell salt and also a. potas
17. A mixture of effective amounts of solid wa
ter-insoluble sodium and potassium metaphos
55 phates and sodium and potassium carbonates
characterized by the fact that when such mix
ture is added to water a reaction takes place re
sulting in the dissolving of the sodium and po
sium salt, said Maddrell salt being added in 60 tassium metaphosphates in the water to form
a solution which exhibits the property of soften
amount su?icient to soften the water.
4. The process as in claim 3, in which a potas
ing water in a manner typical of sodium phos—
phate glass of, the Graham's salt type, of dis
solving calcium and magnesium soaps, and of
monium salt.
.
>
5. The process of softening water by adding 65 having a stable calcium repression after boiling
for a period of time exceeding several hours.
to it a metaphosphate Solution in su?icient
18. A composition comprising e?'ective amounts
amount to soften the water, said metaphosphate
of water-insoluble sodium metaphosphate and
solution being obtained by dissolving the form
potassium carbonate. which mixture when added
of potassium metaphosphate usually referred to
to water in a concentration of 8 grams of water
as potassium Kurrol salt in an aqueous solution
70 insoluble sodium metaphosphate per liter of wa
containing sodium ions.
ter, is characterized by the fact that a reaction
6. The process of softening water by adding to
between the carbonate and the metaphosphate
it a metaphosphate solution in su?lcient amount
occurs whereby the metaphosphate dissolves to
to soften the water. said metaphosphate solution
being obtainedby dissolving the form of po 75 produce an aqueous solution that exhibits the
property of softening water against soap, and of
sium salt is replaced, at least in part, by an am
2,405,276
9
.
.
resisting reversion of the metaphosphate to
orthophosphate at boiling temperature for a sub
stantially longer period of time than an equiv
alent solution -of Graham’s salt will resist re
version at the same temperature.
'
19. A composition comprising effective amounts
of water-insoluble sodium metaphosphate and
potassium chloride, which mixture when added
i0
Brains of metaphosphate per liter of water, said
mixture of metaphosphate and carbonate being
characterized by the fact that the metaphosphate
is solubilized by the carbonate and that the re
sulting solution vwill soften water and that its
ability to soften water remains substantially un
changed when boiled under re?ux for a period
of about six hours.
~ 23. A composition comprising a mixture of
to water in concentrations ‘of 8 grams of water
insoluble sodium metaphosphate per liter of 10 water-insoluble potassium metaphosphate and
water is characterized by the fact that a reac- , ’ sodium carbonate, the amount of carbonate be
ing such as to form about a 0.50% solution when
tion between the potassium chloride and the
said mixture is added to water in the ratio ofv 9.2
metaphosphate occurs whereby the metaphos
grams of metaphosphate per liter of water, said '
"phate is dissolved, the rate of solution being rel
mixture of metaphosphate and carbonate being
atively slow at room temperature and relatively
characterized by the fact that the metaphos
rapid at temperatures up to and including 100° 0.,
phate is solubilized by thecarbonate and that
‘ which solution on dissolution of the metaphos
the resulting solution will soften water. and that
phate has the property of softening hard water
its ability to soften water remains substantially
against soap when added to hard water in the
unchanged when boiled under reflux for a period
ratio of about 9 to 10 milliliters per 5 milligrams
of about six hours.
of calcium ion or magnesium ion.
24. A composition comprising a mixture of
20. A composition comprising‘ a mixture of
water-insoluble sodium metaphosphate and a
Water-insoluble sodium metaphosphate and po
water-soluble compound selected from the group’
tassium carbonate in the ratio of about 8 grams
consisting of potassium and ammonium salts, the
of metaphosphate to about 14 grams of potas
water-soluble compound in said mixture being
sium carbonate, which mixture‘ when added to
in amount suii‘lcient to cause dissolution of the
water and boiledis characterized by a chemical
water-insoluble sodium metaphosphate when said
reaction that results inrelatively rapid dissolu
mixture is added to water, and to impart to said
tion of the metaphosphate, which solution, when
the metaphosphate is dissolved, has the property 30 phosphate properties characteristic of Graham’s
salt with respect to calcium and magnesium ions.
of softening water containing calcium or mag
' 25. A composition comprising a mixture of
nesium ion, about 9 to 10 milliliters of the phos
water-insoluble potassium metaphosphate and a
phate carbonate solution being required to soften
water-soluble compound selected from the group
a water containing about 5 milligrams of calcium
35 consisting of sodium and ammonium salts, the
ion.
'
amount of water soluble compound in said mix
21. A composition comprising a mixture of
ture being such as to form 'a concentration of
water-insoluble sodium metaphosphate and wa-'
about a 0.5% solution when said mixture is added
tor-insoluble potassium metaphosphate in the
to, water in the ratioof about 9 grams of potas
ratio of 4 grams of water-insoluble sodium meta
phosphate to 4.62 grams of water-insoluble po 40 sium metaphosphate per liter of water, the water
soluble compound causing said potassium meta
tassium metaphosphate, which mixture when
phosphate to dissolve when said mixture is added
added to water in the ratio of about 8.62 grams
per liter of water, and boiled ischaracterized by. . to water and to impart to said dissolved phos
relatively rapid dissolution of the metaphos
phates and the formation of a solution having
the property of softening hard water against soap
and having a softening e?iciency substantially
equal to an equivalent amount of Graham's salt.
22. A composition comprising a. mixture of
phate properties characteristic oi’ Graham's salt
with respect to calcium andmagnesium ions.
26. A composition according to claim 25 in
which the sodium and ammoniumsalts are alka
line, characterized by the fact that said alkaline
salts impart greater resistance against reversion
- water-insoluble sodium metaphosphate and po 50 of the dissolved phosphate to orthophosphate
when aqueous solutions of the mixture are heated
tassium carbonate, the amount of carbonate be
to temperatures up to boiling.
I
]
ing such as to form about 0.65% solution when
AMBROSE GEORGE TAYLOR.
said mixture is added to water in the ratio of B
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