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  1. #181
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    "This was quite a scandal in the late 50s when it became public. I'm surprised that you never heard of this. (This information comes from my Air Force magazines in the 50s, which is the official US Air Force publication for all officers.)"

    Langley Air Force base was on the other side of the field, had no fighter command there AFIK, and almost all NACA flight research was done in the desert. I may have heard about it, but that was 50 years ago, and by that time I was into Simulation and Human Factors work. My best friend and co worker was Dr. Rayford T. Saucer (may he rest in peace), a clinical and experimental psychologist. In the meantime, I have had an attack of miningo-encephalitis which took away a lot of memory paths. I think the memories are still in there somewhere because they return a bit at a time. The human brain is a strange thing.
    Gadget Gainer

  2. #182
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    Quote Originally Posted by gainer View Post
    Saturating a borax (or any other compound) will increase the percentage of soluble impurities. We can decrease that percentage by adding twice or more the amount of borax required to form a saturated solution, thoroughly stirring, settling, decanting the clear liquor, which will contain not only saturated borax but a much larger concentration of impurities than the original borax. Now add water sufficient to form a new saturated borax solution from the "washed" borax. You can use the originally decanted liquor for less critival purposes such as laundry.
    This method can work, but will have the consequence of concentrating any solid impurities or concentrating any impurities less soluable than Sodium Borate. An example here might be Magnesium borate or Calcium borate which might increase in the solids due to their decreased solubility. Another possibility is the concentration of various Sulfates in the solids.

    This would be an efficient method of removing Halides and Nitrates though.

    It does increase the time you invest in purification and the water you use in mixing the solutions. You have to balance that against the expense of just buying a better grade.

    PE

  3. #183
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    Quote Originally Posted by Photo Engineer View Post
    This method can work, but will have the consequence of concentrating any solid impurities or concentrating any impurities less soluable than Sodium Borate. An example here might be Magnesium borate or Calcium borate which might increase in the solids due to their decreased solubility. Another possibility is the concentration of various Sulfates in the solids.

    This would be an efficient method of removing Halides and Nitrates though.

    It does increase the time you invest in purification and the water you use in mixing the solutions. You have to balance that against the expense of just buying a better grade.

    PE
    Still, I would expect most of the insoluble purities to remain in the undissolved sediment along with the excess borax. If, for example, I put 3x as much MC in water as needed to make a saturated solution (we can approximate here) and let it stand after initial agitation, the first liquid decanted should contain 2 or 3 times the soluble impurities and probably of the invisible part of the insoluble impurities. When I decant most of that and add distilled water to saturation, what I decant from that point contains more pure borax than the initial product. I am not going to evaporate to recover any dry solid. I can weigh out the required liquid. The liquid I decant could be evaporated to recover solid borax which should have less of both soluble and insoluble impurity, but this would not be necessary for most of our uses in developers. As I mentioned, a liter of D-76 at 20 C would require 42.5 grams of the saturated solution at 20 C.

    BTW, the MC is stated by Dial Corp. to be non-abrasive, which would require that any silica or diamond particles be very small. It is also claimed to have no chlorine (which may leave soluble chlorides, I guess) and no phosphate.
    Gadget Gainer

  4. #184
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    Well, all I can comment on is that abrasive for skin is different from ability to penetrate a swollen gelatin matrix. These are two different issues as skin does not 'swell' in the sense that gelatin does. Gelatin is designed to be porous and skin is just the opposite.

    PE

  5. #185
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    Quote Originally Posted by Photo Engineer View Post
    Well, all I can comment on is that abrasive for skin is different from ability to penetrate a swollen gelatin matrix. These are two different issues as skin does not 'swell' in the sense that gelatin does. Gelatin is designed to be porous and skin is just the opposite.

    PE
    The statement I saw was with regard to scrubbing bright, shiny aluminum cookware with MC on a damp cloth. They sell other stuff for use on hands. I guess no chlorine, no phosphate and no abrasion are a selling point for people who clean aluminum pots and care what they look like.
    Gadget Gainer

  6. #186

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    Quote Originally Posted by gainer View Post
    IIRC, borax is pure as it comes out of the ground and is (or used to be) hauled away from Death Valley by wagons drawn by 20-mule teams.
    pic

  7. #187
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    The white stuff found in caves near the Potomac is more likely to be limestone, calcium carbonate. It's a little frightening to be in one of those caves and to notice that opposing walls match precisely. They are, for the most part, fault caves, and one wonders if the walls could not as easilly come back together.
    Gadget Gainer

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