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Rosco Bodine
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| Quote: | Originally posted by jpsmith123
A while ago Rosco uploaded patent #6777477.
http://www.sciencemadness.org/talk/viewthread.php?tid=8592&a...
Supposedly bismuth can be used in this process as well as antimony.
Has anyone tried anything with this?
I'm curious about the chemistry of what's going on here. Anyone know what would be the precipitates described in Example 1 that apparently
subsequently dissolve in the ammonia solution? |
Thanks for reminding us of that patent . I had forgotten which one of the many patents had described a soft process for the Bi precursor for use as a
dopant .
I'll have a go at explaining the chemistry which appears likely . Evidently Bi is similar to Sn and Sb in the formation
of amphoteric hydroxides whose character is dependant upon the level of hydration .
Tin salts neutralized in solution at mild temperature form a hydrate Sn(OH)4 , hydrated stannic acid or stannic hydroxide which is amphoteric , that
is it can either function as an acid or a base . For example
as an acid it will react with a stronger base to form a stannate , like ammonium stannate .
Evidently Bismuth likewise forms a hydroxide when a
Bi salt is neutralized in solution at mild temperature ,
forming a hydrated bismuthic acid , Bi(OH)3 , (milk of bismuth) which is likewise amphoteric and forms
with ammonia , an ammonium bismuthate .
These sorts of compounds would probably exist only
in solutions having excess base and they are likely unstable . When heated , the system that allows for their
solubility will be disrupted and the lower hydrated
oxide , less soluble form will be precipitated especially
from a system kept basic by ammonia where the ammonia is lost on heating due to volatility .
BTW , with regards to preparation of Bi nitrate , curiously
Bi metal will dissolve in fused ammonium nitrate to form
Bi(NO3)3 . It seems likely that any of the oxides or hydroxides or carbonates would likewise react .
There is some indication that Antimony or perhaps its oxides may do the same .
Manganese carbonate also reacts , but forms a double salt
nitrate , which is however anhydrous , and the Mn(NO3)2
may possibly be isolatable via some subsequent scheme ,
or the mixed nitrate might be useful in nitrate salt plus acid nitration schemes as a combination dehydrating / nitrating
precursor .
Anyway this scheme may have usefulness as an alternative
for aqua regia or concentrated nitric acid when working with
Bi or Sb metals to form soluble intermediates for further workup .
[Edited on 17-1-2008 by Rosco Bodine]
Attachment: Fused Ammonium Salts as Acids Reactions in Fused Ammonium Nitrate.pdf (540kB)
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tentacles
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Xenoid: I believe the Pb precipitate is Pb(OH)2 - I filter this off. The greenish tint to the solution does not seem to affect the PbO2 plating, my
guess is that this is unconverted Cu(NO3) - or Cu(OH)2. Given that Pb is not a strong reducer for Cu, it's possible the reaction reaches a point where
the Pb doesn't reduce any more Cu out of solution. The HNO3 smell seems to be normal, at least for the Pb(NO3)2 that I have made, both from Ca/Cu(NO3)
and from dissolving in nitric acid - I recrystallized some in the past and it still had the odor. You can also recrystallize the Pb(NO3)2 from the
solution.
Is your lead fairly pure? My wheel weight (3% tin) lead had a white ppt that was actually metastannic acid, even when using the Cu(NO3) reduction
method. Does the white ppct dissolve readily in water? I seem to recall the metastannic acid dissolved without coloring or clouding the solution.
Regarding the brown crud, I've never had this happen but I don't usually brush the copper off. I just leave the lead strips hanging until the Pb
dissolves. Is it possible that it is very finely precipitated copper? Is your calcium nitrate the real Ca(NO3)2 or is it the ammonium complex of Ca
nitrate? I believe mine was not the complexed salt.
[Edited on 17-1-2008 by tentacles]
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Rosco Bodine
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With regards to the Bi doped baked coating on the MnO2
perchlorate anode , my inclination would be to preform the Bi as the finely divided hydroxide , Bi(OH)3 , perhaps by simultaneously running streams of
neutralization equivalents of Bi(NO3)3 in 9 molar HNO3 and NH4OH together with vigorous stirring at a mild or cool temperature , crashing out the
hydroxide , settling and decanting , rinsing the precipitate with distilled H2O .
The pH of this can be adjusted with HNO3 to match the
pH of the Mn(NO3)2 solution , and a mixture then made
which should be okay for use as a dip coating .
Sn(NO3)4 could be made up the same way as the Bi
is handled and added to the coating mixture .
I would save out a portion of this tin nitrate
and use it alone or very lightly doped as as sealing layer
over the spinel interface , before or in alternating fashion
with the MnO2 layers , before getting to the Bi doped
SnO2-MnO2 catalytic outer coating(s) .
What would be the optimum composition for the mixture
I am not sure but my *guess* about a good starting point
would be precursors in mixture resulting in proportions
of the oxides based on the metals on a molar basis
Mn 73% Sn 24% Bi 3% .....up to a mixture having about double that amount of Sn and Bi in the same proportions ,
such as Mn 46% Sn 48% Bi 6% . There is something of a contradiction between the two Shamrock patents here and it may be that the final coating would
be better having MnO2 as a relatively minor ingredient in the final coating which could be more like Sn 85% Bi 10% Mn 5% ,
or even a final coating having no Mn at all , such as
Sn 90% and Bi 10% .
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Xenoid
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@ tentacles
MagicJigPipe is right, I am a silly goose ...
Things appear to be working well now!
The initial problems may have been due to residual sulphate in the Cu nitrate solution, this is always a problem with the Ca sulphate metathesis
reaction. Much of the ppt. was probably Pb sulphate.
Today, I boiled the greenish 400 mls of solution this produced some orangy-brown ppt. When the solution was filtered it had turned, a beautiful
turquoise blue again! I put 20 mls in a small beaker and put a small strip of brushed lead in the solution, after about a minute I pulled it out, it
was dark brown , but there was a hint of "copper colour" in a few places. I put it back and left it longer, another min. or so, and it was covered in
"bubbly" copper, when I pulled it out, within a few seconds it turned dark brown (?oxidation). After leaving it in for several mins a lasting distinct
copper coat apppeared. This started to flake off and eroded Pb was visible underneath.
The "choco-brown" material from last night was actually finely divided Cu/CuO if I'd left it a few more mins, the "copper appearance" would have
become obvious. It dissolved in nitric to give a blue solution.
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Rosco Bodine
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Sherlock and Shamrock part deux
Back before Christmas on Dec. 15 , in the cobalt oxide anode thread I mentioned this patent US4272354 .....
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
....which regards Bi doped SnO2 as a perchlorate anode coating . I don't think I made the connection before , but this patent looks to be the exact
same information in a better formatted form , as is the earlier european patent that was posted earlier which appears to be sort of the original draft
for this patent .
Anyway this US4272354 is easier reading and the charts
are more complete .
Attachment: US4272354 Bismuth DTO perchlorate anode.pdf (253kB)
This file has been downloaded 828 times
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chloric1
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Great
@Xenoid-Well I am glad your single displacement is working. I am not fond of replacing one metal with another as it rarely results in a clean 100%
displacement. In this case you actually want a little cupric ion anyways
@Rosco-Thank you for the "onium salt" document! I have 1Kg of Lab grade ammonium nitrate not sure what to do with it aside from the more obvious
uses. Now I know I got some experimental studies to do.
[Edited on 1/17/2008 by chloric1]
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Xenoid
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Hubert and the KClO3 cell.
After a few calculations, I have figured out Hubert has now been running for 422.5 hours (nearly 18 days) for a total of 912 Ah. After I increased the
current to 3.6 Amps a slight pink colouration appeared in "Purple Haze 2". I have since dropped the current back to 3 Amps, mainly because the power
supply was overheating. I have done 3 or 4 extractions of KClO3 crystals, (it is amazing how 3 - 4 cm of crystals in the cell ends up as 1 cm in the
filter). The cell has been recharged with KCl and continues to operate well, it is still perfectly clear, there is another couple of cm of crystals
accumulated. There is very little change in the electrical parameters since day one. Hubert should continue for a while yet, obviously MnO2 performs
quite well in a chlorate cell.
Mathilda and the perchlorate cell.
Mathilda has completed 118 hours, for a total of 251.5 Ah. Most of this was in the one perchlorate cell, but when the run finished I put her in a
second cell, unfortunately the voltage has now risen to about 5.6 Volts and I am stopping this experiment. Mathilda has performed much better than
Gertrude (mainly because of the higher temperature MnO2 baking). But the performance in a perchlorate cell is by no means satisfactory. Mathilda has
continued to produce brown/black hydrated MnO2 particles in the high pH (11.6) environment of a perchlorate cell. I have done a single extraction of
KClO4 from the 400 ml cell, it's not worth the trouble getting out more. Unless the addition of say Bi, improves the attrition rate, I don't see much
future in MnO2 as a perchlorate coating. I guess if Bi were to increase the oxygen potential, there might be less attrition caused by the aggressive
evolution of this gas.
Perhaps Bi doped SnO2 will prove more satisfactory in the perchlorate environment ...
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Rosco Bodine
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The alkalinity is high and you are still getting chlorine loss
so the current density is also high .
For the desired operating condition IIRC it is needed to
be near neutral and the current density just below what
produces chlorine evolution at near neutral , very slightly basic pH .
You may also need some additive to the electrolyte like
a soluble phosphate , dichromate , and/or MnCl2 at
low levels maybe a tenth to a few tenths gram per liter .
A persulphate additive might help too .
Another thing that could create a voltage gradient problem
particularly in the perchlorate cell is interelectrode spacing , the gap between the working anode surface and the cathode is much too wide for my
comfort on these experimental cells . For the coaxial arrangement it
would be good to try for a relatively narrow gap there , on the order of one half inch to 3/4 inch at the outside limit ,
and get some pumped flow through the assembly using
a small mag drive aquarium circulator for example to keep the electrolyte flowing past the electrodes at a pretty good rate . The wider is the
interelectrode gap , the harder it tends to be on electrodes and particularly on coatings that
are challenged already and barely good enough for the reaction even under the most ideal conditions .
[Edited on 18-1-2008 by Rosco Bodine]
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tentacles
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Rosco: that's good to know, I haven't seen a lot of information on electrode spacing.
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Rosco Bodine
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I think I have seen spacing of 3/8 inch for coaxial
flow-through anode core - cathode housing type assemblies
using PbO2 coated anodes . I know I posted that way back
in the other thread concerning PbO2 anodes . I'll look for that patent again .
Anyway I came across another Bismuth anode coating related patent , US4353790 , which is interesting even though it is not specific to being a
perchlorate anode , but rather as an oxygen anode . This patent is interesting because an oxygen anode having a titanium substrate is something of a
torture test with regards to its likelihood of passivating the substrate , which is precisely the mechanism which is believed also to ultimately cause
perchlorate anodes to fail .
There is some food for thought here with regards then to
the usefulness of Bismuth in the interface or near interface
layering on a titanium substrate , regardless of whatever
eventual outer coatings for specific electrolysis products may
be used for producing things other than oxygen . There is
indication here that Bi doped tin oxide is a superior protective
layer for a titanium substrate as well as having possible catalytic value in the outermost coatings , where that would be specific and selective for
perchorate . So some percentage of Bi doping could be useful for different reasons
in all of the coating layers , from the substrate interface itself
all the way to the outside coating .
[Edited on 18-1-2008 by Rosco Bodine]
Attachment: US4353790 Bismuth Oxide Ti Substrate Oxygen Anode.pdf (409kB)
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Xenoid
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@ tentacles
Pb nitrate method works so well, I am doing a second batch. First batch has run to completion and solution is palest-green. The second batch seemed to
work better from the start, and 8 hours after starting, there were Pb nitrate crystals encrusting the Pb "electrodes" in the cool of the early
morning. When you mentioned Cu contamination, am I right in assuming you used the solution "as is" for plating! I intend to crystallise out the Pb
nitrate.
@ Rosco
Industrial manufacturers run both chlorate and perchlorate cells slightly acid, with pH control in both cases. This has implications for the type of
anodes suitable for "amateur" use. For example, I am thinking that MMO pool chlorinator anodes may not be stable in the pH = 8.5 environment of an
amateur chlorate cell.
I am reminded of P.C.S.Hayfield's comments in his review of coated Ti electrodes, where he mentions alkaline hypochlorite was accidently fed into a Ru
based MMO electrode cell. The electrodes lost 25% of their coating in a few hours ... 
Interestingly he then goes on to say they were still used for another 5 years ...
I ain't addin' no stinkin' additives to any of my cells.... !
With regard to electrode spacing, I think I did a check on this about 6 months ago, when I was messing with the MnO2 treated gouging rods, you had
mentioned the same thing. From memory I measured the voltage at different distances for a constant current, and over the few cm involved in a home
cell there wasn't much difference. For an industrial setup with thousands of electrodes, a .05 volt change would be economically important, at home it
isn't. I'll recheck it, but I assume the results were not startling enough to make me change my ways! My chlorinator electrode assembly had 10mm
electrode spacing and I have not been impressed with it's performance.
I've been toying with the idea of pumping solution around. In particular with regard to a KClO3 cell like "Purple Haze". It's a drag having to remove
all those KClO3 crystals, I was thinking of a continuous filtration setup, and adding KCl back at the same time! All the tiny pumps I have looked at
are the "submersible" type, and are not readily modified. They also have exposed metal in the impellor drive (?rotor). I'm still looking at this,
trying to find something suitable. A peristaltic pump would be suitable, with silicone tubing. I actually have one, I picked up for a few dollars, but
it would be overkill in this situation.
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Rosco Bodine
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It would make sense that the pH is neutral or very close from a reaction standpoint and byproduct chlorine evolution indicator observability. With
regards to the additives , you may well be eschewing success whilst chewing the cud of dead and dying anode crud to forsake these parameters  I think you will find the additives
are necessary when running higher current densities
because their purpose is to interfere with the chlorine byproduct by emulating a membrane cell with a slime
layer on the cathode and perhaps on the anode also .
The additives tend to broaden the useful operating range
of pH and current density and increase efficiency while
protecting the electrodes .
On the spacing , if it doesn't make much difference in the measured voltage at a fixed current ....well okay then maybe it's no big deal .
The Resun King pump that I posted a link and image for in the PbO2 plating scheme was a mag drive hermetically sealed circulator pump which could be
run unsubmerged
and had no metal wetted parts . I think the impeller spindle in those is a ceramic shaft in a teflon journal
and the pump body and impeller is glass filled polypropylene IIRC .
[Edited on 18-1-2008 by Rosco Bodine]
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tentacles
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Many of the small aquarium mag drive pumps ("powerheads") use a ceramic shaft and molded in magnet - they are frequently subjected to seawater The
aquarium systems brand is quality stuff, as are the Danner/"Mag Drive" brands.
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chloric1
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Xenoid-Been thinking about Mitilda and her perchorate endeavor. I believe , as you stated somewhere in the Co3O4 thread, you start a perchlorate cell
with twice recrystallized chorate? About 600gms/L? I am trying to figure out how and why you are running so alkaline. IIRC perchlorate production
is practically nil in alkaline cells. What is the pH of your solution before electroylsis? If I where to guess chlorine loss probably occurs during
the dispropiation of the chlorate via: 4ClO3>3ClO4 +Cl. Analgous to what one might see in a potassium chlorate melt at 400°C. Correct me if I am
in error.
I believe a persulfate would be quite helpfull here. It can oxidize chlorate as well as be acidic and lower pH. Problem is shelf life and low
consumption. Residual sulfates will probably be removed via recyrstallizations.
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12AX7
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| Quote: | Originally posted by Rosco Bodine
by emulating a membrane cell with a slime
layer on the cathode and perhaps on the anode also . |
Say, that reminds me: when running chlorate or perchlorate (with dichromate), my platinized anodes get a yellow slime on them! This is something I
would've never noticed with a graphite anode, if it even ocurred. I don't know about the cathode, it looks normal.
Tim
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chloric1
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Heat gun apparatus update. OK here is what I have so far:
My heat gun has three settings: High,Low, and Off.
I am using a 1 1/2" diameter, 11" long 6061 aluminum tube with OD of 2" so I have a substantial wall thickness
Running for 10 minutes at Low I get a max of 205°C.
When I switch to high the inside glows with hellish glow but only elevates me to 330°C I put my fingers over the ALL the baffles to get it up to 380°C but I don't think this is healthy for my gun. So obviously I need a
70°C increase so I need suggestions as what material to wrap around my monster tube and where to buy them. Some I can find but I am curious what
novel suggestions I know I will get.
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tentacles
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Sounds very similar to my setup - my tube is a bit thinner, also Al, 3/16" wall. But mine gets just hot enough to melt sheet lead (99+%), so should be
about 330C. I have covered the outlet somewhat with some steel bits to get a bit more heat, this should not be a problem for the gun if you don't go
too overboard. It sounds like we may have the same gun. Mine is rated at 1200W, also has H/L/O. I have a thermocouple on it's way to properly
determine temp.
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chloric1
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Yes mine is a Miwaukee 1220HS. Or as I stated to Rosco the $29 special. So I
see you have baked at this temperature how have you been running?
I have read most of the patents that Rosco posted and I definately feel 400-420°C is the idea baking temp for durability. Going to look into ebay
for some heat resistant fabric. Probaby cheaper there.
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Rosco Bodine
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Aluminum or copper would be the worst choices of material for the tube as they are excellent heatsinks .
The Wagner HT3500 which I have , without the nozzle concentrator restrictor reads 570C free air temperature directly at the exit of the nozzle , and
that is using a long extension cord which is dropping it down a bit from where it could be . So the one I showed may do the job if there isn't too
much heat loss in the chamber it is trying to heat . The heat drops very rapidly after exiting the gun .
Some sort of insulated chamber is definitely going to be needed for the target temperature range to be achieved .
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chloric1
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I understand about the heatsink affect quite well. But I did not find anything with the right ID measurements. Besides, this was quite affordabe.
The heat can be trapped in. I am thinking of wrapping in ceramic blanket.
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Rosco Bodine
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One thing I have been considering doing is getting some
rigid insulating board and cutting it into 6 inch squares ,
drilling holes on a diagonal 4 inch pattern near each corner , and a hole saw bored hole about 1 and 3/4 in the middle .......stack the pieces and
snug the foot long stack
together with small threaded rods through the holes
near the corners . Maybe a piece of that inch thick or two inch thick mineral wool rigid board or fiberglass rigid board
or even fire rated suspended ceiling tile boards would work for this .
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chloric1
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Yes I understand what you trying to accomplish here. With just two settings though I might want a little heatsink affect. Without a slight loss, our
improvised tube furnaces would run maybe 470 or 480°C risking damaging the coatings. But, we will need hotter temps for uses not related to MMO
anodes so being versatile is best.
So in summary, a heatsinked furnace with slight insulation to run from 350 to 420° and an option to go to a completely insulated furnace for hotter
work. I am entertaining a stainless wire mess rolled to correct dimensions then perhaps an inch or two of mineral wool wired around the support.
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Rosco Bodine
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I don't think you will need to worry about getting too much heat using a heat gun , getting enough is going to
be the problem .
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chloric1
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Catalyst in the coating!
Rosco if you already mentioned this I am sorry.
I am messing around online today because it is too damn cold to do much. Also, I caused this thread to go offtrack so I found something to put it
back on.
Given Xenoids difficulty in obtaining sufficient yields of perchlorate, I think this patent offers an intriguing possibility. A fluoride doped cobalt
spinel! It stated that a max of 2% by weight of fluoride though. But thats OK
because how much NaF would you put in a NaClO4 cell anyways? Could this keep alkalinity under control?
Attachment: US4514518 Fluoride-substituted Cobalt Spinels.pdf (135kB)
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Rosco Bodine
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Hmmm I'm not sure how much good F doping might have
with regards to perchlorate selectivity , but it seems likely it could toughen a coating and act as a sort of grain modifier . It would probably not
be good to use a
sodium salt as the precursor fluoride , but rather an ammonium salt which would tend to having the ammonium
volatalize on baking and not contribute unwanted Na
as a byproduct .
Really my thinking on this baked anode scheme is that
some barium doping and tin oxide are going to be the
most helpful additives , but F could be useful too , there just isn't as much information to suggest its value in
comparison with those other two .
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